History of virology. Principles of classification of viruses Virology is a science that studies the morphology, physiology, genetics, ecology and evolution of viruses. Stages of development of virology

VIROLOGY

Virology is a branch of biology that studies viruses(from the Latin word virus - poison).

The existence of a virus (as a new type of pathogen) was first proven in 1892 by the Russian scientist D.I. Ivanovsky. After many years of research into diseases of tobacco plants, in a work dated 1892, D. I. Ivanovsky comes to the conclusion that tobacco mosaic disease is caused by “bacteria passing through the Chamberlant filter, which, however, are not able to grow on artificial substrates.” Based on these data, the criteria were determined by which pathogens were classified into this new group: filterability through “bacterial” filters, inability to grow on artificial media, and reproduction of the disease picture with a filtrate free of bacteria and fungi. The causative agent of mosaic disease is called by D.I. Ivanovsky in different ways, the term virus had not yet been introduced, allegorically they were called either “filterable bacteria” or simply “microorganisms”.

Five years later, while studying diseases of cattle, namely foot and mouth disease, a similar filterable microorganism was isolated. And in 1898, when reproducing the experiments of D. Ivanovsky by the Dutch botanist M. Beijerinck, he called such microorganisms “filterable viruses.” In abbreviated form, this name began to denote this group of microorganisms.

In 1901, the first human viral disease was discovered - yellow fever. This discovery was made by the American military surgeon W. Reed and his colleagues.

In 1911, Francis Rous proved the viral nature of cancer - Rous sarcoma (only in 1966, 55 years later, he was awarded the Nobel Prize in Physiology or Medicine for this discovery).

^ Stages of development of virology

Rapid progress in the field of virological knowledge, based largely on the achievements of related natural sciences, has made it possible to in-depth knowledge of the nature of viruses. Like no other science, virology demonstrates a rapid and clear change in levels of knowledge - from the level of the organism to the submolecular.

The given periods of development of virology reflect those levels that were dominant for one to two decades.

^ Body level (30-40s of the XX century). The main experimental model is laboratory animals (white mice, rats, rabbits, hamsters, etc.), the main model virus is the influenza virus.

In the 40s, chicken embryos were firmly established in virology as an experimental model due to their high sensitivity to influenza viruses, smallpox and some others. The use of this model became possible thanks to the research of the Australian virologist and immunologist F. M. Burnet, author of the virology manual “Virus as an Organism.”

The discovery of the phenomenon of hemagglutination by the American virologist Hurst greatly contributed to the study of the interaction of the virus with the cell using the model of the influenza virus and red blood cells.

^ Cell level(50s). A significant event is taking place in the history of virology - the discovery of the possibility of culturing cells under artificial conditions. W. J. Enders, T. Weller, F. Robbins received the Nobel Prize for developing the cell culture method. The use of cell culture in virology was a truly revolutionary event, which served as the basis for the isolation of numerous new viruses, their identification, cloning, and the study of their interaction with cells. It became possible to obtain cultured vaccines. This possibility has been proven using the polio vaccine. In collaboration with American virologists J. Salk and A. Seibin, Soviet virologists M. P. Chumakov, A. A. Smorodintsev and others, a production technology was developed, killed and live vaccines against polio were tested and put into practice. Mass immunization of the child population in the USSR (about 15 million) with live polio vaccine was carried out, as a result the incidence of polio sharply decreased and paralytic forms of the disease practically disappeared. For the development and implementation of the live polio vaccine, M. P. Chumakov and A. A. Smorodintsev were awarded the Lenin Prize. Another important application of the virus cultivation technique was the production of live measles vaccine by J. Enders and A. A. Smorodintsev, the widespread use of which led to a significant reduction in the incidence of measles and is the basis for the eradication of this infection.

Other culture-based vaccines were also widely introduced into practice - encephalitis, foot-and-mouth disease, rabies, etc.

^ Molecular level (60s). In virology, methods of molecular biology began to be widely used, and viruses, due to the simple organization of their genome, became a common model for molecular biology. Not a single discovery of molecular biology is complete without a viral model, including the genetic code, the entire mechanism of intracellular genome expression, DNA replication, processing (maturation) of messenger RNAs, etc. In turn, the use of molecular methods in virology has made it possible to establish the principles of structure (architecture) viral individuals - virions (a term introduced by the French microbiologist A. Lvov), methods of penetration of viruses into the cell and their reproduction.

^ Submolecular level (70s). The rapid development of molecular biology opens up the possibility of studying the primary structure of nucleic acids and proteins. Methods for DNA sequencing and determination of protein amino acid sequences are emerging. The first genetic maps of the genomes of DNA viruses are being obtained.

D. Baltimore and at the same time G. Temin and S. Mizutani discovered reverse transcriptase in RNA-containing oncogenic viruses, an enzyme that transcribes RNA into DNA. Gene synthesis using this enzyme on a matrix isolated from polysome mRNA becomes real. It becomes possible to rewrite RNA into DNA and sequence it.

A new branch of molecular biology is emerging - genetic engineering. This year, a report by P. Berg was published in the USA on the creation of a recombinant DNA molecule, which marked the beginning of the era of genetic engineering. It becomes possible to obtain a large number of nucleic acids and proteins by introducing recombinant DNA into the genome of prokaryotes and simple eukaryotes. One of the main practical applications of the new method is the production of cheap protein preparations that are important in medicine (insulin, interferon) and agriculture (cheap protein feed for livestock). This period is characterized by important discoveries in the field of medical virology. The study focuses on the three most widespread diseases that cause enormous damage to people's health - influenza, cancer, and hepatitis.

The causes of regularly recurring influenza pandemics have been established. Cancer viruses of animals (birds, rodents) have been studied in detail, the structure of their genome has been established, and the gene responsible for the malignant transformation of cells, the oncogene, has been identified. It has been established that hepatitis A and B are caused by different viruses: hepatitis A is caused by an RNA-containing virus classified as a member of the picornavirus family, and hepatitis B is caused by a DNA-containing virus classified as a member of the hepadnavirus family. G. Blumberg, while studying blood antigens among the aborigines of Australia, discovered the so-called Australian antigen, which he mistook for one of the blood antigens. Later it was revealed that this antigen is the hepatitis B antigen, carriage of which is common in all countries of the world. For the discovery of the Australian antigen, G. Blumberg was awarded the Nobel Prize. Another Nobel Prize was awarded to the American scientist K. Gaidushek, who established the viral etiology of one of the slow human infections - kuru, observed in one of the native tribes on the island of New Guinea and associated with a ritual rite - eating the infected brain of deceased relatives. Thanks to the efforts of K. Gaidushek, who settled on the island of New Guinea, this tradition was eradicated and the number of patients decreased sharply.

^ Nature of viruses

General virology

General virology studies the basic principles of the structure and reproduction of viruses, their interaction with the host cell, the origin and distribution of viruses in nature. One of the most important branches of general virology is molecular virology, which studies the structure and functions of viral nucleic acids, mechanisms of viral gene expression, the nature of organisms’ resistance to viral diseases, and the molecular evolution of viruses.

Private virology

Private virology studies the characteristics of certain groups of human, animal and plant viruses and develops measures to combat the diseases caused by these viruses.

Molecular virology

In 1962, virologists from many countries gathered at a symposium in the USA to summarize the first results of the development of molecular virology. At this symposium, terms that were not entirely familiar to virologists were used: virion architecture, nucleocapsids, capsomeres. A new period in the development of virology began - the period of molecular virology. Molecular virology, or molecular biology of viruses, is an integral part of general molecular biology and at the same time a branch of virology. This is not surprising. Viruses are the simplest forms of life, and therefore it is only natural that they have become both objects of study and tools of molecular biology. Using their example, one can study the fundamental principles of life and its manifestations.

Since the late 50s, when a synthetic field of knowledge began to take shape, lying on the border of the inanimate and the living and engaged in the study of the living, the methods of molecular biology poured into virology in an abundant stream. These methods, based on the biophysics and biochemistry of living things, made it possible to quickly study the structure, chemical composition and reproduction of viruses.

Since viruses are ultra-small objects, ultra-sensitive methods are needed to study them. Using an electron microscope, it was possible to see individual viral particles, but their chemical composition can only be determined by collecting trillions of such particles together. Ultracentrifugation methods have been developed for this purpose. Modern ultracentrifuges are complex devices, the main part of which is rotors that rotate at speeds of tens of thousands of revolutions per second.

There is no need to talk about other methods of molecular virology, especially since they change and improve from year to year at a rapid pace. If in the 60s the main attention of virologists was fixed on the characteristics of viral nucleic acids and proteins, then by the beginning of the 80s the complete structure of many viral genes and genomes was deciphered and not only the amino acid sequence was established, but also the tertiary spatial structure of such complex proteins , as a glycoprotein of influenza virus hemagglutinin. Currently, it is possible not only to associate changes in the antigenic determinants of the influenza virus with the replacement of amino acids in them, but also to calculate past, present and future changes in these antigens.

Since 1974, a new branch of biotechnology and a new branch of molecular biology - genetic or genetic engineering - began to develop rapidly. She was immediately assigned to the service of virology.

^ Families including human and animal viruses

Family: Poxviridae (poxviruses)

Family: Iridoviridae (iridoviruses)

Family: Herpesviridae (herpes viruses)

Family: Aflenoviridae (adenoviruses)

Family: Papovaviridae (papovaviruses)

Putative family: Hepadnaviridae (hepatitis B virus-like viruses)

Family: Parvoviridae (parvoviruses)

Family: Reoviridae (reoviruses)

Proposed family: (double-stranded RNA viruses consisting of two segments)

Family: Togaviridae (togaviruses)

Family: Coronaviridae (coronaviruses)

Family: Paramyxoviridae (paramyxoviruses)

Family: Rhabdoviridae (rhabdoviruses)

Putative family: (Filoviridae) (Mapburg and Ebola viruses)

Family: Orthomyxoviridae (influenza viruses)

Family: Bunyaviridae (buyaviruses)

Family: Arenaviridae (arenaviruses)

Family: Retroviridae (retroviruses)

Family: Picornaviridae (picornaviruses)

Family: Caliciviridae (calciviruses)
^

http://9school.3dn.ru/news/obrashhenie_direktora_shkoly/2009-11-27-159

http://www.bajena.com/ru/articles/1085/flu-2/

Flu

Flu(Italian influenza, Latin influentia, literally - influence, Greek Γρίππη) is an acute infectious disease of the respiratory tract caused by the influenza virus. Included in the group of acute respiratory viral infections (ARVI). Periodically spreads in the form of epidemics and pandemics. Currently, more than 2000 variants of the influenza virus have been identified, differing in their antigenic spectrum.

Often, the word “flu” in everyday life is also used to refer to any acute respiratory disease (ARVI), which is erroneous, since in addition to influenza, more than 200 types of other respiratory viruses (adenoviruses, rhinoviruses, respiratory principle viruses, etc.) have been described to date, causing influenza-like illnesses. diseases in humans. Presumably, the name of the disease comes from the Russian word “wheezing” - the sounds made by patients. During the Seven Years' War (1756–1763), this name spread into European languages, denoting the disease itself rather than a separate symptom.

A micrograph of an influenza virus taken using an electron transmission microscope, magnified approximately one hundred thousand times.
^

Influenza virus

The influenza virus belongs to the family of orthomyxoviridae (lat. Orthomyxoviridae) and includes three serovars A, B, C. Viruses of serovars A and B constitute one genus, and serotype C forms another. Each serovar has its own antigenic characteristics, which are determined by nucleoproteins (NP) and matrix protein antigens. Serovar A includes subtypes that differ in their hemagglutinin (H) and neuraminidase (N) characteristics. Viruses of serovar A (less often B) are characterized by frequent changes in the antigenic structure when they remain in natural conditions. These changes lead to many subtype names, which include the place of primary appearance, number and year of isolation, HN characteristics - for example A/Moscow/10/99 (H3N2), A/New Caledonia/120/99 (H1N1), B/Hong Kong/ 330/2001.

The influenza virus has a spherical shape with a diameter of 80-120 nm, in the center there are RNA fragments enclosed in a lipoprotein shell, on the surface of which there are “spikes” consisting of hemagglutinin (H) and neuraminidase (N). Antibodies produced in response to hemagglutinin (H) form the basis of immunity against a specific subtype of influenza pathogen.

Spreading

All age categories of people are susceptible to influenza. The source of infection is a sick person with an obvious or erased form of the disease, releasing the virus by coughing, sneezing, etc. The patient is contagious from the first hours of the disease until the 3-5th day of illness. It is characterized by an aerosol (inhalation of tiny drops of saliva, mucus that contain the influenza virus) transmission mechanism and extremely rapid spread in the form of epidemics and pandemics. Influenza epidemics caused by serotype A occur approximately every 2-3 years, and those caused by serotype B occur every 4-6 years. Serotype C does not cause epidemics, only isolated outbreaks in children and weakened people. It occurs more often in the form of epidemics in the autumn-winter period. The frequency of epidemics is associated with frequent changes in the antigenic structure of the virus when it remains in natural conditions. High-risk groups are children, the elderly, pregnant women, people with chronic heart disease, lung disease, and individuals with chronic renal failure.

History of epidemics, serotype A

Influenza has been known since the end of the 16th century.

Year Subtype Distribution

1889-1890 H2N8 Severe epidemic

1900-1903 H3N8 Moderate epidemic

1918-1919 H1N1 Severe pandemic (Spanish flu)

1933-1935 H1N1 Medium epidemic

1946-1947 H1N1 Medium epidemic

1957-1958 H2N2 Severe pandemic (Asian flu)

1968-1969 H3N2 Mild pandemic (Hong Kong flu)

1977-1978 H1N1 Medium pandemic

1995-1996 H1N1 and H3N2 Severe pandemic

2009 H1N1 Mild pandemic (Swine flu)

Development of the disease - pathogenesis

The entry gates for the influenza virus are the cells of the ciliated epithelium of the upper respiratory tract - the nose, trachea, and bronchi. The virus multiplies in these cells and leads to their destruction and death. This explains irritation of the upper respiratory tract, coughing, sneezing, and nasal congestion. Penetrating into the blood and causing viremia, the virus has a direct, toxic effect, manifested in the form of fever, chills, myalgia, and headache. In addition, the virus increases vascular permeability, causes the development of stasis and plasma hemorrhages. It can also cause inhibition of the body’s defense systems, which leads to secondary infection and complications.

Pathological anatomy

Throughout the entire tracheobronchial tree, detachment of the epithelium, the formation of arcade-shaped structures of the epithelium of the trachea and bronchi due to uneven edema and vacuolization of the cytoplasm and signs of exudative inflammation are observed. A common characteristic symptom is hemorrhagic tracheobronchitis of varying severity. In foci of influenza pneumonia, the alveoli contain serous exudate, erythrocytes, leukocytes, and alveolocytes. In areas of inflammation, vascular thrombosis and necrosis are common.

Clinical picture

Symptoms of influenza are not specific, that is, without special laboratory tests (isolation of the virus from throat swabs, direct and indirect immunofluorescence on smears of the epithelium of the nasal mucosa, a serological test for the presence of anti-influenza antibodies in the blood), it is impossible to reliably distinguish influenza from other acute respiratory viral infections. In practice, the diagnosis of “influenza” is established on the basis only of epidemic data, when there is an increase in the incidence of ARVI among the population of a given area. The difference between the diagnoses of “flu” and “ARVI” is not fundamental, since the treatment and consequences of both diseases are identical, the differences lie only in the name of the virus that caused the disease. The flu itself is one of the Acute Respiratory Viral Infections.

The incubation period can range from several hours to 3 days, usually 1-2 days. The severity of the disease varies from mild to severe hypertoxic forms. Some authors indicate that a typical influenza infection usually begins with a sharp rise in body temperature (up to 38 ° C - 40 ° C), which is accompanied by chills, fever, muscle pain, headache and a feeling of fatigue. As a rule, there is no discharge from the nose; on the contrary, there is a pronounced feeling of dryness in the nose and throat. Usually a dry, tense cough appears, accompanied by pain in the chest. With a smooth course, these symptoms persist for 3-5 days, and the patient recovers, but for several days a feeling of severe fatigue persists, especially in elderly patients. In severe forms of influenza, vascular collapse, cerebral edema, hemorrhagic syndrome develop, and secondary bacterial complications occur. Clinical findings during an objective examination are not pronounced - only hyperemia and swelling of the mucous membrane of the pharynx, pallor of the skin, injected sclera. It should be said that influenza poses a great danger due to the development of serious complications, especially in children, elderly and weakened patients.

Complications of influenza

The incidence of complications of the disease is relatively low, but if they develop, they can pose a significant danger to the patient’s health. Moderate, severe and hypertoxic forms of influenza can cause serious complications. The causes of complications with influenza may be the following features of the infectious process: the influenza virus has a pronounced capillary-toxic effect, is capable of suppressing the immune system, and destroys tissue barriers, thereby facilitating tissue aggression by resident flora.

^ There are several main types of complications from influenza:

Pulmonary: bacterial pneumonia, hemorrhagic pneumonia, lung abscess formation, empyema formation.

Extrapulmonary: bacterial rhinitis, sinusitis, otitis, tracheitis, viral encephalitis, meningitis, neuritis, radiculoneuritis, liver damage, Reye's syndrome, myocarditis, toxic-allergic shock.

Most often, deaths from influenza occur among children under 2 years of age and elderly people over 65 years of age.

Treatment

Until recently, treatment was usually symptomatic, in the form of antipyretics, expectorants, and antitussives, as well as vitamins, especially vitamin C in large doses. The CDC recommends that patients rest, drink plenty of fluids, and avoid smoking and drinking alcohol.

^ Immune-stimulating drugs

Prevention and early treatment of colds with high doses of vitamin C (ascorbic acid) was advocated by Linus Pauling, a two-time Nobel Prize winner. Thanks to his authority, this method became widespread. It is usually recommended to take no more than 1g of ascorbic acid per day.

There are also a number of more modern immunostimulants that can be used for prevention and treatment in the early stages of influenza. Among them are arbidol (a relatively weak immunomodulator) and groprinosin (a stronger immunomodulator, the use of which requires medical supervision).

^ Antiviral drugs

It is assumed that antiviral drugs that act on one or another phase of the development of a viral infection in vitro can also show effectiveness in vivo, especially as a prophylactic agent. In general, treatment with antiviral drugs should begin before the onset of clinical manifestations of influenza; starting them later is practically ineffective.

^ Neuraminidase inhibitors

One of the drugs that has proven effectiveness in treating influenza is oseltamivir ( Tamiflu) and zanamivir ( Relenza). These neuraminidase inhibitors are effective against many strains of influenza, including avian influenza. These drugs suppress the spread of the virus in the body, reduce the severity of symptoms, shorten the duration of the disease and reduce the incidence of secondary complications. However, there is evidence that these drugs cause a number of side effects, such as nausea, vomiting, diarrhea, as well as mental disorders: impaired consciousness, hallucinations, psychosis.

Immunoglobulins

Special strictly controlled studies have shown that only donor serum and anti-influenza gamma globulin, containing high titers of antibodies, have a clear antiviral and therapeutic effect on influenza. Gamma globulin should be prescribed intramuscularly as soon as possible: children 0.15-0.2 ml/kg, adults 6 ml. In the same doses, normal (placental) gamma globulin and serum polyglobulin can be used.

^ Interferon preparations

This substance has antiviral and immunostimulating effects. Interferons are most effective in the initial phase (first three days) of the disease.

^ Symptomatic treatment

To facilitate nasal breathing, naphthyzine, sanorin, and galazolin are effective. However, they should not be used regularly, but as needed (when the nose is stuffy), otherwise bleeding will occur.

^ Flu prevention

The traditional way to prevent influenza is vaccination. It is carried out with an influenza vaccine corresponding to the leading strain and, as a rule, contains antigens of three strains of influenza virus, which are selected based on the recommendations of the World Health Organization. A vaccine for the prevention of influenza has been proposed in the form of a liquid, killed, subjective vaccine. Vaccination is especially indicated in risk groups - children, elderly people, patients with chronic heart and lung diseases, as well as doctors. It is usually carried out when the epidemiological forecast indicates the advisability of mass events (usually in mid-autumn). A second vaccination is also possible in the middle of winter.

The effectiveness of vaccination depends on how well the creators can predict the strains circulating in a given epidemiological season. In addition to vaccination, intrazonal administration of interferon is used for emergency prevention of influenza and Acute Respiratory Viral Infection. This method is used when there is a fear of getting sick after contact with patients with a respiratory infection, during an epidemic rise in incidence. In this case, interferon blocks the replication of viruses at the site of their introduction into the nasal cavity.

As a non-specific prophylaxis, wet cleaning is carried out in the room where the flu patient is located using any disinfectant that has a virucidal effect. Ultraviolet irradiation, aerosol disinfectors and catalytic air purifiers are used to disinfect the air. Patients who sneeze and cough are dangerous to others. Prevention of influenza must necessarily include removing them from public places (by calling for people to be conscious). There are often cases of going to court against patients who came to work while still on sick leave.

Forecast

With uncomplicated influenza, the prognosis is favorable. In severe cases of influenza and complications, death may occur.

^ SWINE FLU

WITH Blame the flu(English: Swine flu) is the conventional name for a disease in humans and animals caused by strains of the influenza virus. The title was widely circulated in the media in early 2009. Strains associated with outbreaks of the so-called. “swine flu”, found among influenza viruses of serotype C and subtypes of serotype A (A/H1N1, A/H1N2, A/H3N1, A/H3N2 and A/H2N3). These strains are known collectively as swine flu virus. Swine flu is common among domestic pigs in the United States, Mexico, Canada, South America, Europe, Kenya, mainland China, Taiwan, Japan and other Asian countries. In this case, the virus can circulate among people, birds and other species; this process is accompanied by its mutations.

^ A/H1N1 virus under an electron microscope. The diameter of the virus is 80-120 nm.

Epidemiology

Transmission of the virus from animal to human is rare, and properly cooked (heat-treated) pork cannot be a source of infection. When transmitted from animals to humans, the virus does not always cause disease and is often detected only by the presence of antibodies in human blood. Cases where transmission of the virus from an animal to a person leads to illness are called zoonotic swine flu. People who work with pigs are at risk of contracting the disease, but only about 50 such cases have been reported since the mid-1920s (when influenza virus subtypes first became possible to identify). Some of the strains that have caused disease in humans have become capable of being transmitted from person to person. Swine flu causes symptoms in humans that are typical of influenza and ARVI. The swine flu virus is transmitted both through direct contact with infected organisms and by airborne droplets (see Mechanism of transmission of the infectious agent).

Etiology

Swine flu symptoms. The 2009 outbreak of a new strain of influenza virus, known as “swine flu,” was caused by the H1N1 subtype of virus, which is most genetically similar to the swine flu virus. The origin of this strain is not precisely known. However, the World Organization for Animal Health reports that epidemic spread of the virus of the same strain could not be established among pigs. Viruses of this strain are transmitted from person to person and cause illness with symptoms common to the flu. Pigs can be infected with the human influenza virus, and this is what may have happened during both the Spanish flu pandemic and the 2009 outbreak.

Pathogenesis

In general, the mechanism of action of this virus is similar to that of other strains of the influenza virus. The entry gate of infection is the epithelium of the mucous membranes of the human respiratory tract, where its replication and reproduction occur. Superficial damage to the cells of the trachea and bronchi is observed, characterized by processes of degeneration, necrosis and rejection of the affected cells.

The development of the pathological process is accompanied by viremia, lasting 10–14 days, with a predominance of toxic and toxic-allergic reactions from internal organs, primarily the cardiovascular and nervous systems. The main link in the pathogenesis is damage to the vascular system, manifested by increased permeability and fragility of the vascular wall, and impaired microcirculation. These changes manifest themselves in patients with the appearance of rhinorrhagia (nosebleeds), hemorrhages on the skin and mucous membranes, hemorrhages in the internal organs, and also lead to the development of pathological changes in the lungs: edema of the lung tissue with multiple hemorrhages in the alveoli and interstitium. A decrease in vascular tone leads to venous hyperemia of the skin and mucous membranes, congestive plethora of internal organs, impaired microcirculation, diapedetic hemorrhages, and in later stages - thrombosis of veins and capillaries. These vascular changes also cause hypersecretion of cerebrospinal fluid with the development of circulatory disorders, leading to intracranial hypertension and cerebral edema.

Clinic

The main symptoms are the same as the usual flu symptoms - headache, fever, cough, vomiting, diarrhea, runny nose. A significant role in the pathogenesis is played by damage to the lungs and bronchi due to increased expression of a number of factors - inflammatory mediators (TLR-3, γ-IFN, TNFα, etc.), which leads to multiple damage to the alveoli, necrosis and hemorrhage. The high virulence and pathogenicity of this strain of the virus can be due to the ability of the non-structural protein NS1 (inherent in this virus) to inhibit the production of type I interferons by infected cells. Viruses defective in this gene are significantly less pathogenic.

Diagnostics

Clinically, the course of this disease generally coincides with the course of the disease when infected with other strains of the influenza virus. A reliable diagnosis is established by serotyping the virus

Prevention

For the purpose of primary specific prevention (primarily for persons at risk), the Russian Federation and abroad are accelerating the development and registration of specific vaccines based on the isolated strain of the pathogen. Epidemiologists also welcome vaccination against “seasonal” flu, which contains antibodies against damaging agents (proteins) of three types of virus that differ from the “swine” strain.

The WHO advisory on highly pathogenic influenza states the need to avoid close contact with people who “appear unwell, have a fever and a cough.” It is recommended to wash your hands thoroughly and frequently with soap. “Adopt a healthy lifestyle, including getting enough sleep, eating healthy foods, and being physically active.” With proper heat treatment, the virus dies. Primary non-specific prevention is aimed at preventing the virus from entering the body, and at strengthening the non-specific immune response to prevent the development of the disease.

Treatment

Treatment of a disease caused by strains of the swine flu virus is essentially no different from the treatment of the so-called “seasonal” flu. In case of severe symptoms of intoxication and disturbances of the acid-base balance, detoxification and corrective therapy is carried out. Of the drugs that act on the virus itself and its reproduction, the effectiveness of Oseltamivir (Tami-Flu) has been proven. In its absence, WHO experts recommend the drug Zanamivir (Relenza); for relatively mild cases of the disease, doctors in post-Soviet countries recommend Arbidol, despite the fact that it is a drug with unproven effectiveness, and the WHO does not consider it at all as an antiviral drug. Treatment of severe and moderate cases is aimed at preventing primary viral pneumonia, which is usually severe and causes hemorrhage and severe respiratory failure, and at preventing the addition of a secondary bacterial infection, which also often causes the development of pneumonia.

Symptomatic therapy is also indicated. Among antipyretic drugs, most experts recommend drugs containing ibuprofen and paracetamol (it is not recommended to use drugs containing aspirin due to the risk of developing Reye's syndrome.

Urgent contact with medical institutions (calling an ambulance) is necessary for signs of severe respiratory failure, depression of brain activity and dysfunction of the cardiovascular system: shortness of breath, shortness of breath, cyanosis (blue skin), fainting, the appearance of colored sputum, low blood pressure, chest pain.

A mandatory visit to a doctor (usually to a local clinic) is necessary in case of a high temperature that does not decrease on the 4th day, or a marked deterioration of the condition after a temporary improvement.

^

A number of new antiviral drugs are currently being studied, incl. Peramivir.

Recommendations for the prevention and treatment of influenza from the Ministry of Health and Social Development of the Russian Federation.

^

The Ministry of Health and Social Development of the Russian Federation has released “Temporary guidelines for the treatment and prevention of influenza A/H1N1.”

Temporary guidelines for the treatment and prevention of influenza caused by the A/H1N1 virus for adults and children were prepared jointly with leading research institutes of the Russian Academy of Medical Sciences, the Influenza Research Institute, the Institute of Epidemiology and Microbiology named after. N.F. Gamaleya and the Federal State Institution “Research Institute of Childhood Infections” and the Research Institute of Pulmonology of the Federal Medical and Biological Agency of Russia.

^

Epidemics caused by the H1N1 influenza virus

Pandemic in 1918 - “Spanish Flu”

Main article: Spanish flu

The Spanish flu or "Spanish flu" (French: La Grippe Espagnole, or Spanish: La Pesadilla) was most likely the worst influenza pandemic in the history of mankind. In 1918-1919, approximately 50-100 million people died from the Spanish flu worldwide. About 400 million people, or 21.5% of the world's population, were infected. The epidemic began in the last months of the First World War and quickly eclipsed this largest bloodshed in terms of casualties.

^

1976 influenza outbreak

1988 flu outbreak

2007 influenza outbreak

On August 20, 2007, the Philippine Department of Agriculture reported an outbreak of H1N1 influenza in swine farms in Nueva Ecija province and central Luzon.

^

Influenza A/H1N1 pandemic 2009. Outbreak of the H1N1 influenza virus in 2009.

In April-May 2009, an outbreak of a new strain of influenza virus was observed in Mexico and the United States. The World Health Organization (WHO) and the US Centers for Disease Control and Prevention (CDC) have expressed serious concern about this new strain due to the potential for human-to-human transmission, the high mortality rate in Mexico, and because this strain could develop into a flu pandemic. On April 29, at an emergency meeting, WHO increased the level of pandemic threat from 4 to 5 points (out of 6 possible).

As of August 27, 2009, there have been approximately 255,716 cases of influenza A/H1N1 infections and 2,627 deaths reported in more than 140 regions around the world. In general, the disease with this flu proceeds according to the classical scenario, the frequency of complications and deaths (usually due to pneumonia) does not exceed the average for seasonal flu.

At the moment, there is debate around what to call this strain of influenza. So, on April 27, 2009, “swine flu” was called “California 04/2009”; on April 30, pork producers advocated renaming “swine flu” to “Mexican”; a clear non-scientific name has not yet been invented.

The fifth threat level was announced at the end of April 2009: in accordance with the WHO classification, this level is characterized by the spread of the virus from person to person in at least two countries in the same region.

On June 11, 2009, WHO declared a swine flu pandemic, the first pandemic in 40 years. On the same day, he was assigned the sixth degree of threat (out of six). The WHO threat level does not characterize the pathogenicity of the virus (that is, the danger of the disease to human life), but indicates its ability to spread. Thus, any flu transmitted from person to person reaches the sixth degree of threat.

However, WHO's concerns are related to the genetic novelty of the California strain and its potential for further reassortment, which could result in the emergence of more aggressive variants of the infection. Then, by analogy with the most destructive pandemics of the last century, this virus will lead to serious human losses after a certain (usually six-month) period, accompanied by relatively moderate mortality.

^

Spanish flu or "Spanish flu"

(French: La Grippe Espagnole, or Spanish: La Pesadilla) was most likely the worst influenza pandemic in human history. In 1918-1919 (18 months), approximately 50-100 million people, or 2.7-5.3% of the world's population, died from the Spanish flu worldwide. About 500 million people, or 21.5% of the world's population, were infected. The epidemic began in the last months of the First World War and quickly eclipsed this largest bloodshed in terms of casualties.

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Picture of the disease, name “Spanish flu”

The Spanish flu virus is similar to the H1N1 virus that caused the 2009 pandemic. In May 1918, 8 million people or 39% of its population were infected in Spain (King Alfonso XIII also suffered from the Spanish flu). Many flu victims were young and healthy people in the 20-40 age group (usually only children, the elderly, pregnant women and people with certain medical conditions are at high risk).

Symptoms of the disease: blue complexion - cyanosis, pneumonia, bloody cough. In later stages of the disease, the virus caused intrapulmonary bleeding, as a result of which the patient choked on his own blood. But mostly the disease passed without any symptoms. Some infected people died the day after infection.

The flu got its name because Spain was the first to experience a severe outbreak of the disease. According to other sources, it is not yet possible to determine exactly where it appeared, but, most likely, Spain was not the primary epidemic focus. The name "Spanish flu" appeared by chance. Since the military censorship of the fighting parties during the First World War did not allow reports of the epidemic that had begun in the army and among the population, the first news about it appeared in the press in May-June 1918 in neutral Spain. The participants in the World War began to call her the Spanish Flu. The name of the disease stuck mainly due to newspaper hype in Spain, since Spain did not participate in hostilities and was not subject to military censorship.

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Flu and its ghosts

Picture copied: http://holimed.lviv.ua/rus/rozsylka/kakbolet/010.html

The influenza virus that is rampant this year is A/California/09/2009 (H1N1), where A is the type of virus (the one that, unlike types B and C, mutates very easily and affects people and animals), California is the place origin, 09 – strain number, 2009 – year of appearance, H1N1 – serotype (that is, a certain subtype of influenza A virus, which differs from others in a set of antigens that determine its toxicity, ability to overcome the body’s defense systems, “infectiousness”, etc.) . This is precisely the influenza virus that is now causing massive morbidity.

Not every cold is worth looking for the flu. Malaise and runny nose can be caused by any of the viruses that are “responsible” for the occurrence of ARVI (acute respiratory viral infections).

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Symptoms of the flu (any kind!) are as follows:

1. very abrupt onset of the disease,

a sharp increase in body temperature - up to 39°C and above,

severe headaches, joint and muscle pain,

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nasal congestion, sore throat, dry cough.

Usually, after 3-4 days the temperature drops and, if the disease proceeds without complications (which, in fact, are dangerous for the flu), recovery occurs after 7-10 days.

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Complications of influenza:

1. lesions of the respiratory tract (bronchitis and pneumonia);

diseases of the ENT organs (sinusitis, otitis, tonsillitis);

damage to the cardiovascular system (myocarditis, myocardial dystrophy);

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damage to the central nervous system (meningitis, encephalitis); kidney damage (pyelonephritis, glomerulonephritis).

In people with chronic diseases (for example, bronchial asthma, arterial hypertension), their exacerbation due to influenza is very likely.

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At-risk groups (according to severe course and consequences!):

pregnant women, young children, elderly people, adults and children with serious chronic diseases, as well as in the presence of immunodeficiency (meaning pathological conditions).

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Flu prevention .

The general rules that are important for absolutely everyone are the following:

Wash your hands frequently with soap and water for 20 seconds.

Cough and sneeze into a tissue or hand.

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Do not approach patients closer than one and a half to two meters.

Sick children should stay at home (not attend preschools and schools),

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and also keep a distance from other people until their condition improves.

Refrain from visiting stores, cinemas or other crowded places.

What to do if a child gets sick?

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Leave a sick child at home unless he or she needs medical attention.

Give your child plenty of fluids (juice, water, etc.).

Create a comfortable environment for the sick child. Rest is extremely important.

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Give your child the medications the doctor prescribes.

Keep tissues and a trash can for used tissues within the patient's reach.

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Avoid contact of a sick child with healthy family members.

If your child has been exposed to someone who has H1N1 influenza, ask your doctor about taking medications to prevent illness from H1N1 influenza.

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Olga Zorina

Medical Editorial Studio MedCorr.

http://holimed.lviv.ua/rus/rozsylka/kakbolet/010.html

Alexander Zadorozhny

How to get the flu correctly

Doctor, I have the flu, what do you advise me?
- Stay away from me.

There is probably no person in the world who has not had the flu at least once. And this is not surprising - every year up to 15% of the world's population falls ill with this disease. The attitude of different people towards the flu varies: from absolutely indifferent to panic. Those who do not distinguish the flu from a banal ARVI (acute respiratory viral infection) treat it with disdain and self-confidence, and those who have already had a negative experience with the real flu treat it with caution and prefer to avoid getting sick again.

What is the flu really like? According to the WHO (World Health Organization), influenza is a potentially fatal disease, and this assessment is not unfounded.

Influenza is an acute infectious disease that affects the respiratory, nervous, cardiovascular and other systems. ^ The causative agent of influenza is a virus that multiplies in the mucous membrane of the respiratory tract. It spreads in the air with tiny droplets of saliva, mucus and sputum secreted by sick people and carriers when sneezing, coughing, or talking. The main difference between influenza from other acute respiratory viral infections (ARVI), which it begins acutely, that is, suddenly. After a latent (incubation) period lasting no more than two days, flu symptoms appear.

^ The characteristic features of influenza are a sharp increase in body temperature (up to 40°C), intense headache, pain and aches throughout the body and muscles, photophobia (painful or unpleasant to look at light), pain when moving the eyes. The rise in temperature is accompanied by severe chills. The flu is literally shocking with its symptoms - high fever, terrible weakness. All this may be accompanied by signs of incipient respiratory damage: nasal congestion, sore throat and a typical flu-like sensation of rawness in the chest. On the 2nd day of the disease, a painful cough and pain behind the sternum along the trachea often occur, resulting from damage to the tracheal mucosa. But most often, cough and runny nose come later or do not appear at all.

Other ARVIs, unlike the flu, gain momentum gradually, starting with a sore throat, runny nose, sneezing and general lethargy. On the third or fourth day, the temperature begins to rise. And with the flu, complications already begin by this day. It is the complications that pose the greatest danger to the health and life of a flu patient. As a rule, they develop during the flu and/or during the first two weeks after the illness.

^ The most common complications of influenza:

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  Secondary bacterial respiratory diseases (pneumonia, bronchitis, meningitis, laryngotracheobronchitis, ear infections, otitis media, etc.);
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  Exacerbation of chronic lung diseases (asthma, bronchitis, etc.);
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  Decompensation of cardiovascular diseases (myocarditis, pericarditis);
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  Inflammation of the kidneys, exacerbation of renal failure;
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  Exacerbation of endocrine disorders (diabetes mellitus);
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  Pathologies of pregnancy.
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  Exacerbation of neurological disorders, radiculitis.

Complications of influenza require hospital treatment. Complications of influenza can be deadly - almost all deaths from influenza are caused by a developed complication. Most complications of influenza are the result of improper treatment and improper behavior of patients.

How to properly get the flu in order to get out of it safely and avoid complications? Let's try together to understand what exactly happens in the body during the flu. To do this, first we will get acquainted with the main culprit of the problems - the causative agent of influenza. This pathogen is a virus.

Viruses, unlike other representatives of the living world, are not, strictly speaking, independent living organisms. Outside living objects, they have the appearance of an organic substance with a crystalline structure, without signs of life, but when they enter a cell they “come to life”.

Hemagglutinin is a surface protein of the influenza virus that ensures the ability of the virus to attach to the host cell.

Neuraminidase is a surface protein of the influenza virus that responds

Firstly, for the ability of a viral particle to penetrate a cell, and,

Secondly, for the ability of viral particles to leave the cell after reproduction.

Nucleocapsid is the genetic material (RNA) of the virus enclosed in a protein shell (capsule).

Infection with the influenza virus, as well as other acute respiratory viral infections, occurs through the upper respiratory tract. If inhaled, Viruses attach to cells using hemagglutinin. The enzyme neuraminidase destroys the cell membrane of mucosal cells, and the virus penetrates into the cell. This process is possible only at pH 5-6, that is, in an acidic environment. The viral RNA then penetrates the cell nucleus and causes it to produce new viral particles according to its program. As they accumulate in the cell, new viruses are released (at the same time the cell is destroyed and lysed) and infect other cells.

Reproduction of viruses can occur at an exceptionally high speed: if one viral particle enters the upper respiratory tract, after 8 hours the number of infectious offspring can reach 10³, and by the end of the first day - 10²³. The high rate of reproduction of the influenza virus explains such a short incubation period (the time elapsed from the moment of infection to the appearance of signs of the disease) - 1-2 days. One infected cell produces many hundreds of virions.

The viruses then enter the bloodstream and spread throughout the body. Exactly the release of viruses into the blood and their distribution throughout the body is one of the main causes of severe intoxication during influenza. Unlike most other viruses that cause colds, acute respiratory viral infections, the influenza virus has an envelope consisting of lipids, which are the main factor causing severe intoxication. The process of virus reproduction occurs at a temperature of 32-37°C, and at temperatures above 38°C this process slows down and stops with a further increase. At the same time, with an increase in body temperature, processes develop in the body that contribute to the death of viruses.

An indispensable condition for the penetration of the virus into the cell is the presence of an acidic environment with a pH of 5-6. Normally, the reaction of the blood, as well as the mucous secretions of the respiratory tract, is slightly alkaline: pH greater than 7, which in itself represents a natural obstacle to the penetration of the virus. But when the mucous membrane cools, the vessels narrow, blood flow worsens and acid accumulates in the tissue - the pH decreases and, accordingly, favorable conditions arise for the virus to penetrate into the cell.

Therefore, the first rule of flu prevention : breathe exclusively through your nose. Nasal breathing, firstly, helps to warm the air entering the bronchi and lungs, and this protects the airways from cooling. Secondly, when passing through the nasal passages, the air is cleared of all foreign particles contained in it, including viruses, which are deposited on the nasal mucosa and then, together with the mucus, with the help of special villi, are removed through the esophagus into the stomach, where they are neutralized .

Second rule: Make sure your feet and hands are always warm. There is a reflex connection between them and the upper respiratory tract (URT): a decrease in the temperature of the feet and hands leads to a deterioration in blood circulation in the mucous membrane of the URT and a decrease in their temperature. And, conversely, warming the legs and arms, accordingly, helps improve blood circulation and increase the temperature of the mucous membrane of the upper respiratory tract. Unfortunately, very often there is a situation when a person’s feet are constantly cold, but he doesn’t even notice it. In this case, regular contrast baths on the feet and hands are usually recommended. It is best to do them as needed, but at least 1-2 times a day, especially at night.

The procedure is carried out as follows. Warm water is poured into a basin or bathtub. The initial temperature of the water should be slightly higher than the temperature of the feet, so that the water subjectively feels warm. Then, as the feet warm, hot water is gradually added. The maximum water temperature is 41-42°C. The duration of the procedure is at least 15 minutes, or up to an hour, until the feet become red and a feeling of warmth appears throughout the body. If you have a runny or stuffy nose, then the disappearance of these symptoms may also be a criterion for completing the procedure.

After warming up your feet, you must immediately dip them in cold water or pour cold water over them from a jug. The colder the water, the stronger the effect. If this is not done, then after a short time the legs will cool down and the procedure will be ineffective.

Many people are afraid to pour cold water on their feet, but if you warm up well, then in addition to the benefits, you will also get pleasure. After pouring cold water over your feet, you need to rub them dry and put on socks. After this, it is advisable to walk for 10-15 minutes. This contrast dousing stimulates blood circulation in the legs and, if you perform this procedure regularly, you will feel that your legs are no longer cold. And this is important for the prevention of flu and colds.

The same procedure can be carried out simultaneously, if necessary, for the hands. But it often happens that warming the feet helps warm the hands and this is a criterion for completing the procedure. If this does not happen, it is advisable to warm your hands separately. It is very important to do the contrast bath exactly as described.

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It is important to constantly ensure that your feet do not freeze.

If you have a stuffy nose or runny nose, it is advisable to limit your fluid intake; it is better to drink fluids in the evening, when you no longer plan to go out into the cold.

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Third rule - drink less fluid, especially if you are often exposed to cold conditions.

The fourth rule of preventing influenza infection - if possible, avoid unnecessary contacts, especially in public places and transport, use protective masks.

During a flu epidemic, it is necessary to limit the consumption of protein foods, which acidify the body, and increase the content of raw (live) foods (apples, cabbage, parsley, celery, Jerusalem artichoke, oranges, tangerines, lemons, etc.). Raw potatoes have good preventive and therapeutic properties against influenza. It contains a large amount of vitamin C, as well as substances with anti-influenza activity. Raw foods should be consumed at every meal. It's better to start with them. This contributes to a high content of leukocytes in the peripheral blood, and, accordingly, maintaining a high level of immunity. It is also good to use live, freshly squeezed juices (fresh) as drinks.

To prevent influenza, you can use 0.25% oxolin ointment. During the period of rise and maximum outbreak of influenza (usually for 25 days), or upon contact with patients with influenza, for individual prevention of influenza, use 0.25% ointment, which is used to lubricate the nasal mucosa twice a day (morning and evening). Oxolin prevents the virus from reproducing.

All of these above rules for preventing influenza help before infection with the influenza virus - before it enters the mucous membrane of the respiratory tract and penetrates the cells of the mucous membrane. After this, as you already know, viruses multiply in the cells of the mucosa. And then the second stage of the influenza process begins - the release of the virus into the bloodstream (this condition is called viremia). Here, all preventive measures aimed at preventing influenza infection are no longer useless and measures related to the development of influenza disease are necessary.

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Alexander Zadorozhny

The flu is not as bad as the complications after it, says one woman to another.

- I know this from my own experience. Just after the flu, I married a local doctor.

Last time, we examined in detail the process of infection (infection) of the body with the influenza virus and the conditions under which this infection occurs. I hope that you have taken into account and taken advantage of the recommendations for preventing influenza disease given in the last issue.

Today I will talk about how to behave if you do get the flu: how to get the flu correctly. Correct behavior at the stage of manifestation of the influenza process in the event of infection will help not only prevent the development of complications, but also, as paradoxical as it sounds, achieve a healing effect. This means that if you treat the flu correctly, you can come out of the disease healthier than before.

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Every year, usually during the cold season, influenza epidemics occur and affect up to 15% of the world's population: both people and animals and birds.

The influenza virus is characterized by antigenic variability, which is a fundamental feature of influenza viruses types A and B. As a rule, every year changes occur in the structure of the surface antigens of the virus - hemagglutinin and neuraminidase. As a result of this variability, new types (strains) of the influenza virus arise, to which people who have previously had the flu lack immunity.

To carry out its life cycle (reproduction), the influenza virus penetrates into the cell. This process is possible only at pH 5-6, that is, in an acidic environment.

Viral RNA, the genetic code of the virus, penetrates the cell nucleus and causes it to produce new viral particles according to its program. As they accumulate in the cell, new viruses are released (at the same time the cell is destroyed and lysed) and infect other cells. One infected cell produces many hundreds of virions.

During the process of reproduction, viruses enter the blood and spread throughout the body. The release of influenza viruses into the blood is accompanied by chills and a subsequent rise in temperature. It is the release of viruses into the blood and their distribution throughout the body that marks the beginning of the period of acute clinical manifestations of influenza.

The course of the disease depends on the specific immunity of the body - the presence of antibodies to the type of influenza virus that has entered the blood, as well as on the level of nonspecific resistance (resistance) of the body, which depends on one or another combination of many factors that determine the general level of human health.

With a sufficiently high level of body resistance, after the first release of viral bodies into the blood, their further reproduction in the body does not occur and the disease gradually declines.

If there are places in the body where there are conditions favorable for the penetration of viruses into cells, a new cycle of their reproduction occurs, followed by the death of infected cells and the repeated release of viral particles into the blood, the course of the disease becomes more severe and the likelihood of developing complications and the transition of the disease to a hypertoxic form increases.

Depending on the general state of health, age, and whether the patient has previously been in contact with this type of virus, he may develop one of 4 forms of influenza: mild, moderate, severe and hypertoxic. In severe cases of influenza, irreversible damage to the cardiovascular system, respiratory organs, and central nervous system often occurs, causing heart and vascular diseases, pneumonia, tracheobronchitis, and meningoencephalitis. With the hypertoxic form of influenza, there is a serious risk of death (death). After suffering from the flu, symptoms of post-infectious asthenia may persist for 2-3 weeks: fatigue, weakness, headache, irritability, insomnia, etc.

The development of a viral process in the human body requires significant expenditure of energy and material resources; this is accompanied by blocking of natural physiological processes, which leads to the accumulation of toxic products which, in turn, also contribute to a significant deterioration in the general condition of the flu patient.

Why do mutations of the influenza virus constantly occur, as a result of which, unlike other viral infections, it is impossible to develop stable immunity to the influenza virus?

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What is the influenza virus for, what function does it perform in nature?

Why does a person need to get the flu?

The answers to these questions will help us understand how to properly get sick with the flu. Therefore, I ask you to accept the information presented below as a working hypothesis necessary for understanding the algorithm of behavior during influenza.

Today, there is very strong evidence that viruses, including the influenza virus, play a very important role in the exchange of genetic information between various living organisms. Such an exchange is necessary for better adaptation of living organisms to a changing external environment. Are viruses the carriers of “best practices in the biosphere” in relation to highly organized organisms? And the most important role in this belongs to the influenza virus.

At the cellular level, we are all mutants, and we cannot be different, since evolutionary progress is nothing more than a process of changing the genetic structure of populations towards increasing the diversity of forms and their better adaptation to environmental conditions.

Medical valeology - a science that studies the processes of individual health - notes one important pattern: the more energy accumulated in each individual cell and, accordingly, in the body as a whole, the greater the range of external influences it can withstand, and the higher the level of human health. At a high level of health, the processes of energy supply to cells occur in an aerobic mode (with good access to oxygen). The lower the level of health, the lower the level of aerobic oxidation and the higher the level of anaerobic processes. This produces a large amount of lactic acid, which creates an acidic environment around the cells.

A high level of health guarantees reliable protection against infection with the virus. In a healthy body there are no conditions for infection. The weaker the body, the lower its level of health, the more acidified the tissues are with the waste products of cells. The most productive in this regard are cancer cells, which, unlike healthy cells, provide themselves with energy primarily anaerobically (without access to oxygen).

Thus, the lower the level of human health, the more cells working in anaerobic mode. In such an organism, favorable conditions are created for infection with the virus. We can say that with a low level of health, the body seems to need infection with a virus. Sounds paradoxical, doesn't it? But if you think about it, it turns out that cancer cells are most susceptible to infection by the influenza virus. And the virus itself is the magic bullet that can kill a cancer cell. It can be assumed that infection with the influenza virus helps rid the body of cancer and other weakened, non-viable cells.

So, your task during the process of suffering from the flu is “the birth of a new harmonious world”: increasing the level of your health. To do this, you will need to mobilize your forces as much as possible, combine them with the forces of the enemy (flu) and direct this combined energy to improve the health of your loved one. Therefore, all our actions during influenza should be aimed not at fighting the virus, but at optimizing the processes occurring in the body during the flu and using the body’s reaction to the influenza virus for health purposes. In practice, this means that we, as it were, use the influenza virus that has entered our body as a medicine. We give it the opportunity to “walk” a little through our body, identify all the diseased cells and destroy them. At the same time, we use the ability of the influenza virus to mobilize the body’s defenses and processes and launch healing and cleansing reactions. Correct behavior during flu is like a controlled nuclear reaction at a nuclear power plant: if we do everything correctly, we will benefit, if control is lost, we will suffer.

What should be the sequence of your actions? There are many processes in the human body that require energy. With the flu, the need for energy increases sharply, so the body takes emergency measures to increase metabolic processes, which is accompanied by severe chills. To help yourself in this situation, you need to take measures to saturate your body with warmth: steam your feet, take a bath, cover yourself with heating pads, wrap yourself in a blanket, drink hot tea with lemon. Warming should continue until the chills stop. Further, to reduce energy consumption and mobilize strength, firstly, bed rest is necessary. Digesting food is very costly from the point of view of the body's energy, therefore, secondly, it is best to stop eating food, especially protein and thermally processed food - it requires very high energy costs. Thirdly, it is necessary to ensure the neutralization and removal of “waste” and toxins from the body.

With influenza, there are two main sources of intoxication. The first is influenza viruses circulating in the blood, and the second is the large intestine. In any disease accompanied by a deterioration in the general condition (well-being) of a person, especially with influenza, there is an increase in the permeability of the intestinal barrier, resulting in an increase in the absorption of intestinal toxins into the blood, which further aggravate the patient’s condition. Therefore, at the first signs of malaise, it is best to first cleanse the intestines. This can be done in various ways:

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1. Using an enema.

2. Taking laxatives.

3. A combination of the first and second methods.

I will dwell in detail on the administration of an enema. Its purpose is to empty the intestines of feces, which are a source of intoxication. We need to prepare a pear for performing an enema, with a volume of 200-500 ml, and also, as a working fluid, an aqueous solution of salt, since the enema should be slightly hypertonic - 1.5-2%. To do this, dissolve one teaspoon (with top) of kitchen salt in 500 ml of water. Before performing an enema, be sure to make sure that your feet are warm - then the procedure will be effective. If necessary, you can make a foot bath, as was described in the last issue of the newsletter. If you are chilling, the water temperature should be about 39-40°C, but if you are hot - 30-35°. After introducing the liquid into the rectum, you need to hold it until the urge appears. If emptying was insufficient, the procedure can be repeated.

In addition to an enema, activated charcoal is very helpful for quick detoxification. To carry out detoxification, you need to take 25-30 g of activated carbon (100-120 tablets!). Coal must be ground in a coffee grinder or ground into a fine powder in a mortar or other container. If you use an electric coffee grinder, do not open the lid immediately, let the coal dust settle. Then carefully pour the coal powder into a glass with 100 ml of water, stir gently until the coal is wetted with water, then shake and quickly drink the coal suspension. What is left should be eaten with a spoon, then rinse your mouth with water. Attention! Under no circumstances should you try to swallow dry charcoal powder and be careful that the powder does not get into your respiratory tract! More comfortable for oral administration are the modern preparations of activated carbon that exist today, soluble in water, with a large surface area and, accordingly, a lower dosage.

To cleanse the intestines, only osmotic laxatives can be taken as a laxative for influenza. These include saline laxatives such as Carlsbad salt, Truskavets "Barbara" salt, magnesium sulfate (magnesia). A 20-25% saline laxative solution is taken: 1-2 tablespoons per 150-250 ml of alkaline mineral water of the Borjomi type. Sodium thiosulfate is used as an antitoxic agent in the form of a 10-15% solution - 2 teaspoons per 100-150 ml of water. Ready-made Morshyn ropa and Hungarian mineral water “Hunyadi Janos” are used in the amount of 100-150 ml per dose. You can also use a food substitute for sugar, sorbitol: 1-2 tablespoons per 150-250 ml of water. Sorbitol can be added to tea with lemon. This procedure is called intestinal lavage.

Before taking a laxative solution, you also need to make sure that your feet are warm. It is better to take a laxative on an empty stomach, then it will work faster. In case of cholelithiasis, this procedure must be carried out carefully, the concentration of solutions should be 2-3 times less, and if there are attacks, it is better to abandon it. After taking a laxative, you need to lie on your right side on a warm heating pad for about an hour until you feel thirsty, after which you can drink some liquid. It is better not to use medicinal laxatives for the flu. These procedures: cleansing the intestines and taking activated charcoal significantly improves the condition of a patient with influenza, headaches and body aches decrease or disappear completely, and the temperature decreases. You need to repeat such cleansing every day until complete recovery.

When the influenza process manifests itself, an increase in body temperature occurs - this is an adaptive reaction that contributes to a sharp acceleration of all physiological processes in the body, including the synthesis of interferon, which blocks the biosynthesis of viral particles in the infected cell and thereby reduces the development of the viral process. In addition, as I mentioned earlier, when body temperature rises above 38°C, the process of virus reproduction slows down and with a further increase, it stops. At the same time, due to an increase in body temperature, processes develop in the body that contribute to the improvement of impaired metabolism (metabolism), the elimination of metabolic and oxygen debt in cells and tissues, the death of non-viable and diseased cells and the removal of toxic products from the body.

Many people are afraid of high temperatures, especially in children. In fact, the rise in temperature is not that bad and is quite manageable. The only organ that is “afraid” of a temperature rise to 40°C is the brain. He really can't stand overheating. The rest of the body only benefits from such a rise in temperature. Therefore, never try to bring down your temperature at any cost, especially if you are sick with the flu. If the temperature is brought down with antipyretic drugs, the virus continues to multiply and its quantity in the body will increase catastrophically, accordingly its toxic damaging effect will increase, that is, the disease will worsen - there will be more damaged cells, organs and tissues - the recovery period will be longer and the risk of developing complications due to viral damage to the body.

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A child’s high temperature, of course, must be controlled. But it is better to do this using natural methods. An antipyretic drug, as a last resort, can be given once (this is for faint-hearted parents, for self-soothing) - if the temperature drops and then rises again, then it is not worth giving again - there may be complications and the disease may progress to a protracted course.

The brain suffers the most from temperature, so everything must be done to ensure the outflow of heat from the head. This includes compresses on the head, undressing the child, and wiping him with a damp towel. You need to pay attention to the child’s condition: if he is chilly, it is better to wipe him with warm water, if he is warm, you can wipe him with cool water. In any case, pay attention to how the child reacts to wiping - if he doesn’t like it, change the temperature regime to the opposite.

Pay attention to the child's limbs - hands and feet, as well as to the skin. If they are cold, you need to warm them in warm water (bath) or in another way (a heating pad, rubbing or warming with warm hands), as soon as they warm up, the blood flow to them will increase and, accordingly, heat transfer will increase and the temperature will definitely drop by 0.5- 1 degree. At the same time, apply a damp compress to the forehead (cloth moistened with water). This is often enough to make the child feel more comfortable and, perhaps, fall asleep.

The cause of spasms in children at elevated temperatures is overheating of the brain and a large temperature difference between the brain and extremities. Conclusion: if the child has warm hands and feet and the head is sufficiently cooled (through removable compresses) everything will be fine. Of course, these procedures require patience and time (it’s easier to give a pill), but the child will come out of the disease not only not weakened, but on the contrary, will gain useful life experience and immunity. Pay attention to the child’s psychological state: if he is in a good mood and playing, you don’t have to worry too much about the elevated temperature. If he cries, is capricious, or weakened, lethargic, he requires increased attention and observation. The most important thing that is required from parents is patience and perseverance. Of course, it’s easier to give a fever pill and go to sleep, but this temporary relief can later lead to unpleasant consequences and prolong the process

I hope you now know how to control the temperature. I just want to warn you that a high temperature with the flu can last for 3-4 days, especially if you haven’t cleansed your intestines enough, continue to eat, don’t keep bed rest, or your body is heavily polluted. Therefore, following the recommendations on the regimen and detoxification of the body will contribute to a faster recovery from the disease. My observations indicate that if all recommendations are followed correctly and accurately, the illness lasts no more than 4-5 days.

There are times when the body is not able to respond to illness by increasing body temperature. And such a rise in the flu is extremely necessary. One of the fathers of medicine said something like this about this: “Give me a remedy to raise the temperature and I will cure any disease.” That is why thermal procedures in the form of a bath are so popular among all peoples as a means of treatment and healing. Therefore, if you do not have a fever with the flu, you will have to take all measures to increase it.

If the intoxication is not very pronounced and you have the strength, you can take a warm bath, gradually increasing its temperature, but not too zealously, so as not to weaken completely. You can do an enema right in the bath, if the appropriate conditions exist. Having warmed up in this way, you need to put on cotton underwear or a tracksuit, go to bed, wrapped in a blanket and covered with heating pads. It is necessary to place a thermometer in the armpit area to monitor body temperature and lie there without opening until the temperature rises to 38.5°C-39°C. The head should be open and, if necessary, it can be cooled with compresses. If you don’t have the strength for a bath, then you can immediately start by warming up in bed - it will be a little slower. For better warming, it’s very good to drink 150-200 ml of hot tea with honey and lemon.

So, you've cleaned yourself, warmed up, what's next? And then you need to start drinking diaphoretic tea little by little. It can be raspberry, linden tea, tea with elderflowers... You need to drink in small portions - 1-2 sips every 10-15 minutes, so it is better to keep the tea in a thermos or in a water bath so that it does not cool down. The diaphoretic tea should not be very hot. When you start to sweat, try to stay open for as long as possible to avoid cooling down. If you try really hard, this state of sweating can last 3-4 hours. If you feel weak or hungry, you can add honey to your tea. If you are weak, you can also drink alkaline mineral water such as “Borjomi” or cucumber or cabbage brine, diluting it by half or two-thirds with water.

When you have the flu, it is very important to stay in bed and get as much sleep as possible. This is necessary to reduce the load on the heart, which works very intensely during flu. Sleep promotes less blood flow to the head and thereby protects the brain from the effects of toxins. When the temperature returns to normal, the signs of intoxication disappear and a feeling of hunger appears - do not rush to eat up - for a day or two it will be enough to drink fruit juices or eat raw fruits or vegetables until you are completely sure of your recovery. And if you follow the recommendations given here correctly, it will come within 4-5 days. After this, you will need to take a bath or shower to wash off all the sweat and dirt that has accumulated on your body during your illness. If you have the strength, you can take a bath every day. After the bath you will feel how refreshed your body is. If you have ever tried to fast for at least 10 days in your life, then you will be able to evaluate your condition after 3-5 days of proper flu illness - it can be compared to the condition that occurs after cleansing the body with hunger. Confirmation of this may be another pleasant for many, but there may be a somewhat unexpected consequence of correct behavior during the flu: a decrease in body weight to 2-5 kg.

Finally, I would like to say that the basic principles described here are applicable to any acute illness. I will briefly list them again: fasting, cleansing through the intestines (enemas, intestinal lavage) and skin (sweating), detoxification (with activated carbon), bed rest, maintaining, and not knocking down, high body temperature, drinking regime that ensures sufficient sweating, but drinking should not be excessive and too abundant.

History of virology. Principles of virus classification

Virology is the science that studies the morphology, physiology, genetics, ecology and evolution of viruses

The word "virus" meant poison. This term was also used by L. Pasteur to designate an infectious principle. Currently, a virus refers to tiny replicating microorganisms found wherever there are living cells.

The discovery of viruses belongs to the Russian scientist Dmitry Iosifovich Ivanovsky, who in 1892 published a work on the study of tobacco mosaic disease. D.I. Ivanovsky showed that the causative agent of this disease is very small in size and does not linger on bacterial filters, which are an insurmountable obstacle for the smallest bacteria. In addition, the causative agent of tobacco mosaic disease is not able to be cultivated on artificial nutrient media. D.I. Ivanovsky discovered plant viruses.

In 1898, Loeffler and Frosch showed that foot-and-mouth disease, a widespread cattle disease, was caused by an agent that also passed through bacterial filters. This year is considered the year of discovery of animal viruses.

In 1901, Reed and Carroll showed that filterable agents could be isolated from the corpses of people who died of yellow fever. This year is considered the year of discovery of human viruses.

D'Herrel and Twort in 1917-1918 discovered viruses in bacteria, calling them “bacteriophages.” Later, viruses were isolated from insects, fungi, and protozoa.

Viruses still remain one of the main causative agents of infectious and non-infectious human diseases. About 1000 different diseases are viral in nature. Viruses and the human diseases they cause are the object of study in medical virology.

Viruses have fundamental differences from other prokaryotic microorganisms:

1. Viruses do not have a cellular structure. These are precellular microorganisms.

2. Viruses have submicroscopic sizes, varying in human viruses from 15-30 nm to 250 nm or more.

3. Viruses contain only one type of nucleic acid: either DNA or RNA, where all the information of the virus is encoded.

4. Viruses do not have their own metabolic and energy systems.

6. Viruses are not capable of growth and binary fission. They reproduce by reproducing their proteins and nucleic acid in the host cell, followed by the assembly of a viral particle.

Due to their characteristics, viruses are classified into a separate kingdom Vira, which includes viruses of vertebrate and invertebrate animals, plants and protozoa. The modern classification of viruses is based on the following main criteria:

1. Type of nucleic acid (RNA or DNA), its structure (single or double stranded, linear, circular, continuous or fragmented).

2. The presence of a lipoprotein membrane (supercapsid).

3. Viral genome strategy (i.e., the transcription, translation, replication pathway used by the virus).

4. Size and morphology of the virion, type of symmetry, number of capsomeres.

5. Phenomena of genetic interactions.

6. Range of susceptible hosts.

7. Pathogenicity, including pathological changes in cells and the formation of intracellular inclusions,

8. Geographical distribution.

9. Method of transmission.

10. Antigenic properties.

Based on criteria 1 and 2, viruses are divided into subtypes and families, and based on the characteristics listed below - into genera, species, and serovars. The name of the family ends in "viridae", some families are divided into subfamilies (ending in "virinae"), genera - "vims". Human and animal viruses are distributed in 19 families: 13 RNA genomic and 6 DNA genomic. The classification and some properties of human and animal viruses are presented in table. 1.

Table 1

CLASSIFICATION AND SOME PROPERTIES OF VIRUSES

HUMAN AND ANIMALS

KINGDOM V1RA
Virus family	Nucleic acid type	Presence of a supercapsid	Virion size. nm	Typical representatives
DNA GENOMIC VIRUSES
Adenoviridae	Linear, double-stranded	-	70-90	Adenoviruses of mammals and birds
Herpesviridae	linear double-stranded	+	220	Viruses of herpes simplex, cytomegaly, chickenpox, infectious mononucleosis
Hepadnaviridae	Double-stranded, annular with a single-stranded section	+	1 45-50	Hepatitis B virus
Papovaviridae	double-stranded, ring	-	45-55	Papilloma viruses, polyomas
Poхviridae	Double-stranded with closed ends	+	130-250	Vaccinia virus, variola virus
Parvoviridae	linear, single-strand	-	18-26	Adeno-associated virus
RNA GENOMIC VIRUSES
Areoaviridae	fragmented single-stranded	+	50-300	Viruses Lassa, Machupo
Bunyaviridae	fragmented single-stranded ring	+	90-100	Viruses of hemorrhagic fevers and encephalitis
Caliciviridae	single-strand	-	20-30	Hepatitis E virus, human caliciviruses
Coronaviridae	single-stranded +RNA	+	80-130	Human coronaviruses
Orthomyxoviridae	single-stranded, fragmented -- RNA	+	80-120	Influenza viruses
Paramyxoviridae	Single-stranded, linear -RNA	+	150-300	Parainfluenza, measles, mumps, PC virus
Picornaviridae	single-stranded +RNA	-	20-30	Polio, Coxsackie, ECHO, hepatitis A viruses, rhinoviruses
Reoviridae	double-stranded RNA	-	60-80	Reoviruses, rotaviruses
Retroviridae	single-stranded RNA	+	80-100	Viruses of cancer, leukemia, sarcoma, HIV
Togaviridae	single-stranded +RNA	+	30-90	Sindbis viruses. Horse Encephalitis. krasthi
Flaviviridae	single-stranded +RNA	+	30-90	Viruses of tick-borne encephalitis, yellow fever, Dengue, Japanese encephalitis, hepatitis C, G
Rhabdoviridae	single-stranded RNA	+	30-40	Rabies virus, vesicular stomatitis virus
Filoviridae	single-stranded +RNA	+	200-4000	Ebola viruses, Marburg

Morphology and ultrastructure of viruses

Based on their structure, there are 2 types of viral particles: simple and complex.

The internal structure of simple and complex viruses is similar.

The core of the virus is the viral nucleic acid, the viral genome. The viral genome can be represented by one of 4 RNA or DNA molecules: single-stranded and double-stranded RNA and DNA. Most viruses have one whole or fragmented genome, which has a linear or closed shape. Single-stranded genomes can have 2 polarities: 1) positive, when the virion nucleic acid simultaneously serves as a template for the synthesis of new genomes and acts as an mRNA; 2) negative, performing only the function of a matrix. The genome of viruses contains from 3 to 100 or more genes, which are divided into structural, encoding the synthesis of proteins that make up the virion, and regulatory, which change the metabolism of the host cell and regulate the rate of virus reproduction.

Viral enzymes are also encoded in the genome. These include: RNA-dependent RNA polymerase (transcriptase), which is found in all negative-sense RNA viruses. Poxviruses contain a DNA-dependent RNA polymerase. Retroviruses have a unique enzyme, an RNA-dependent DNA polymerase called reverse transcriptase. The genome of some viruses contains genes encoding RNases, endonucleases, and proteinases.

On the outside, the nucleic acid is covered with a protein cover - a capsid, forming a complex - a nucleocapsid (in the chemical sense - a nucleoprotein). The capsid consists of individual protein subunits - capsomers, which represent a polypeptide chain laid in a certain way, creating a symmetrical structure. If the capsomeres are arranged in a spiral, this type of capsid folding is called helical symmetry. If capsomeres are stacked along the faces of a polyhedron (12-20-hedron), this type of capsid stacking is called icosahedral symmetry

The capsid is represented by α-helical proteins capable of polymerization, which protect the genome from various influences, perform a receptor function in this group of viruses, and have antigenic properties.

Complex viruses have an outer shell, the supercapsid, located on top of the capsid. The supercapsid consists of an internal protein layer - M-protein, then a more voluminous layer of lipids and carbohydrates extracted from the cell membranes of the host cell. Virus-specific glycoproteins penetrate inside the supercapsid, forming shaped protrusions on the outside that perform a receptor function. Viruses exist in three forms:

1) virion (viral particle) - extracellular form;

2) intracellular (vegetative) virus;

3) a virus integrated with the host DNA (provirus).

Interaction of virus with cell. Reproduction (multiplication) of viruses

The process of viral reproduction can be roughly divided into 2 phases . The first phase includes 3 stages: 1) adsorption of the virus on sensitive cells; 2) penetration of the virus into the cell; 3) deproteinization of the virus . The second phase includes the stages of implementation of the viral genome: 1) transcription, 2) translation, 3) replication, 4) assembly, maturation of viral particles and 5) virus exit from the cell.

The interaction of a virus with a cell begins with the adsorption process, i.e., with the attachment of the virus to the cell surface.

Adsorption represents the specific binding of the virion protein (antireceptor) to the complementary structure of the cell surface - the cell receptor. According to their chemical nature, the receptors on which viruses are fixed belong to two groups: mucoprotein and lipoprotein. Influenza viruses, parainfluenza, and adenoviruses are fixed on mucoprotein receptors. Enteroviruses, herpes viruses, arboviruses are adsorbed on lipoprotein receptors of the cell. Adsorption occurs only in the presence of certain electrolytes, in particular Ca2+ ions, which neutralize excess anionic charges of the virus and cell surface and reduce electrostatic repulsion. Adsorption of viruses depends little on temperature. The initial processes of adsorption are nonspecific in nature and are the result of electrostatic interaction of positively and negatively charged structures on the surface virus and cell, and then a specific interaction occurs between the virion attachment protein and specific groups on the plasma membrane of the cell. Simple human and animal viruses contain attachment proteins as part of the capsid. In complex viruses, attachment proteins are part of the supercapsid. They can take the form of filaments (fibers in adenoviruses), or spikes, mushroom-like structures in myxo-, retro-, rhabdo- and other viruses. Initially, a single connection of the virion with the receptor occurs - such attachment is fragile - adsorption is reversible. For irreversible adsorption to occur, multiple connections must appear between the viral receptor and the cell receptor, i.e., stable multivalent attachment. The number of specific receptors on the surface of one cell is 10 4 -10 5. Receptors for some viruses, for example, arboviruses. are contained on the cells of both vertebrates and invertebrates; for other viruses only on the cells of one or more species.

Penetration of human and animal viruses into cells occurs in two ways: 1) viropexis (pinocytosis); 2) fusion of the viral supercapsid shell with the cell membrane. Bacteriophages have their own penetration mechanism, the so-called syringe, when, as a result of contraction of the protein appendage of the phage, the nucleic acid is injected into the cell.

Deproteinization of the virus, the release of the viral hemome from the viral protective shells occurs either with the help of viral enzymes or with the help of cellular enzymes. The end products of deproteinization are nucleic acids or nucleic acids associated with the internal viral protein. Then the second phase of viral reproduction takes place, leading to the synthesis of viral components.

Transcription is the rewriting of information from DNA or RNA of a virus into mRNA according to the laws of the genetic code.

Translation is the process of translating genetic information contained in mRNA into a specific sequence of amino acids.

Replication is the process of synthesis of nucleic acid molecules homologous to the viral genome.

The implementation of genetic information in DNA-containing viruses is the same as in cells:

DNA transcription mRNA translation protein

For RNA viruses with a negative genome (influenza viruses, para-influenza viruses, etc.), the genome implementation formula is as follows:

RNA transcription i-RNA translation protein

Viruses with a positive RNA genome (togaviruses, picornaviruses) lack transcription:

RNA protein translation

Retroviruses have a unique way of transmitting genetic information:

RNA reverse transcription DNA transcription mRNA translation protein

The DNA integrates with the genome of the host cell (provirus).

After the cell has accumulated viral components, the last stage of viral reproduction begins: the assembly of viral particles and the release of virions from the cell. Virions exit the cell in two ways: 1) by “exploding” the cell, as a result of which the cell is destroyed. This path is inherent in simple viruses (picorna-, reo-, papova- and adenoviruses), 2) exit from cells by budding. Inherent in viruses containing a supercapsid. With this method, the cell does not die immediately and can produce multiple viral offspring until its resources are depleted.

Virus cultivation methods

To cultivate viruses in laboratory conditions, the following living objects are used: 1) cell cultures (tissues, organs); 2) chicken embryos; 3) laboratory animals.

I. Cell cultures

The most common are single-layer cell cultures, which can be divided into 1) primary (primarily trypsinized), 2) semi-continuous (diploid) and 3) continuous.

By origin they are classified into embryonic, tumor and from adult organisms; by morphogenesis- fibroblastic, epithelial, etc.

Primary Cell cultures are cells of any human or animal tissue that have the ability to grow in the form of a monolayer on a plastic or glass surface coated with a special nutrient medium. The lifespan of such crops is limited. In each specific case, they are obtained from the tissue after mechanical grinding, treatment with proteolytic enzymes and standardization of the number of cells. Primary cultures obtained from monkey kidneys, human embryonic kidneys, human amnion, and chicken embryos are widely used for the isolation and accumulation of viruses, as well as for the production of viral vaccines.

Semi-leathered (or diploid ) cell cultures - cells of the same type, capable of withstanding up to 50-100 passages in vitro, while maintaining their original diploid set of chromosomes. Diploid strains of human embryonic fibroblasts are used both for the diagnosis of viral infections and in the production of viral vaccines.

Continuous cell lines are characterized by potential immortality and a heteroploid karyotype.

The source of transplantable lines can be primary cell cultures (for example, SOC, PES, BNK-21 - from the kidneys of one-day-old Syrian hamsters; PMS - from the kidney of a guinea pig, etc.) individual cells of which show a tendency to endless reproduction in vitro. The set of changes leading to the appearance of such features from cells is called transformation, and the cells of continuous tissue cultures are called transformed.

Another source of transplantable cell lines is malignant neoplasms. In this case, cell transformation occurs in vivo. The following lines of transplanted cells are most often used in virological practice: HeLa - obtained from cervical carcinoma; Ner-2 - from laryngeal carcinoma; Detroit-6 - from lung cancer metastasis to the bone marrow; RH - from human kidney.

For cell cultivation, nutrient media are required, which, according to their purpose, are divided into growth and supporting media. Growth media must contain more nutrients to ensure active cell proliferation to form a monolayer. Supporting media should only ensure that cells survive in an already formed monolayer during the multiplication of viruses in the cell.

Standard synthetic media, such as synthetic media 199 and Eagle's media, are widely used. Regardless of the purpose, all cell culture media are formulated using a balanced salt solution. Most often it is Hanks solution. An integral component of most growth media is animal blood serum (veal, bovine, horse), without the presence of 5-10% of which cell reproduction and monolayer formation do not occur. Serum is not included in the maintenance media.

Isolation of viruses in cell cultures and methods for their indication.

When isolating viruses from various infectious materials from a patient (blood, urine, feces, mucous discharge, organ washings), cell cultures that are most sensitive to the suspected virus are used. For infection, cultures in test tubes with a well-developed monolayer of cells are used. Before infecting the cells, the nutrient medium is removed and 0.1-0.2 ml of a suspension of the test material, pre-treated with antibiotics to destroy bacteria and fungi, is added to each test tube. After 30-60 min. After contact of the virus with cells, excess material is removed, a supporting medium is added to the test tube and left in a thermostat until signs of virus replication are detected.

An indicator of the presence of a virus in infected cell cultures can be:

1) development of specific cell degeneration - cytopathic effect of the virus (CPE), which has three main types: round or small cell degeneration; formation of multinucleated giant cells - symplasts; development of foci of cell proliferation, consisting of several layers of cells;

2) detection of intracellular inclusions located in the cytoplasm and nuclei of affected cells;

3) positive hamagglutination reaction (RHA);

4) positive hemadsorption reaction (RHAds);

5) plaque formation phenomenon: a monolayer of virus-infected cells is covered with a thin layer of agar with the addition of a neutral red indicator (background - pink). In the presence of a virus, colorless zones (“plaques”) form on the pink agar background in the cells.

6) in the absence of CPD or GA, an interference reaction can be performed: the culture under study is re-infected with the virus that causes CPD. In a positive case, there will be no CPP (the interference reaction is positive). If there was no virus in the test material, CPE is observed.

II. Isolation of viruses in chicken embryos.

For virological studies, chicken embryos 7-12 days old are used.

Before infection, the viability of the embryo is determined. During ovoscoping, living embryos are mobile and the vascular pattern is clearly visible. The boundaries of the air sac are marked with a simple pencil. Chicken embryos are infected under aseptic conditions, using sterile instruments, after pre-treating the shell above the air space with iodine and alcohol.

Methods for infecting chicken embryos can be different: applying the virus to the chorion-allantoic membrane, into the amniotic and allantoic cavities, into the yolk sac. The choice of infection method depends on the biological properties of the virus being studied.

Indication of the virus in a chicken embryo is made by the death of the embryo, a positive hemagglutination reaction on glass with allantoic or amniotic fluid, and by focal lesions (“plaques”) on the chorion-allantoic membrane.

III. Isolation of viruses in laboratory animals.

Laboratory animals can be used to isolate viruses from infectious material when more convenient systems (cell cultures or chicken embryos) cannot be used. They take mainly newborn white mice, hamsters, guinea pigs, and rat pups. Animals are infected according to the principle of virus cytotropism: pneumotropic viruses are injected intranasally, neurotropic viruses - intracerebrally, dermatotropic viruses - onto the skin.

Indication of the virus is based on the appearance of signs of disease in animals, their death, pathomorphological and pathohistological changes in tissues and organs, as well as a positive hemagglotination reaction with extracts from organs.

Viral diseases, their features

Viruses, unlike other microorganisms, cause 2 groups of diseases:

1) viral infections,

2) tumors (benign and malignant). Features of viral infections:

1. Viral infections are widespread. Their share in the structure of infectious morbidity can be 60-80%.

2. Intracellular reproduction of viruses leads to massive death of body cells.

3. Reproduction of some viruses (HIV, measles viruses, hepatitis B, C) in the cells of the immune system leads to the development of an immunodeficiency state.

4. The ability of some viruses to integrate with the cell genome (HIV, hepatitis B virus, oncogenic RNA viruses).

5. Some viruses (rubella, cytomegalovirus) have a teratogenic effect.

6. Infectious viruses can provoke the development of tumors (adenoviruses, herpes viruses, hepatitis viruses B, C, G).

7. Viruses can cause slow infections (HIV, measles, rabies, hepatitis B, herpes viruses, etc.).

8. There is no immunoprophylaxis for many viral infections.

9. Diagnosis of viral diseases is not used in every specific case due to the widespread nature of these diseases.

10.To date, there are not enough effective drugs for the treatment of viral diseases.

CLASSIFICATION OF VIRAL INFECTIONS

Cell level

Autonomous infection

Integration infection

productive

Abortive

Whole Genome Integration

Integration of part of the genome

Chronic

Acute

Neoplatic transformation

Lack of transformation

cytolytic

Noncytolytic

Body level

Focal infection

Generalized infection

Persistent

Persistent

At the cellular level, autonomous infections are distinguished if the viral genome replicates independently of the cellular one, and integrated infections if the viral genome is included in the cellular genome. Autonomous infection is divided into productive, in which infectious offspring are formed, and abortive, in which the infectious process is terminated, and new viral particles are either not formed at all or are formed in small quantities. Productive and abortive infections can be acute or chronic. Acute infection, depending on the fate of the infected cell, is divided into cytolytic and non-cytolytic. Cytolytic infection results in cell destruction, or CPD, and the virus that causes CPD is called cytopathogenic.

At the body level, viral infections are divided into 2 groups: 1) focal, when the reproduction and action of the virus manifests itself at the entrance gate; 2) generalized, in which the virus, after multiplying at the entrance gate, spreads to various organs and tissues, forming secondary foci of infection. Examples of focal infections are acute respiratory viral infections and acute respiratory infections, generalized ones are poliomyelitis, measles, smallpox.

An acute infection does not last long, is accompanied by the release of the virus into the environment, and ends with either recovery or death of the body. An acute infection may manifest itself with a number of symptoms (manifest infection), or may be asymptomatic (inapparent infection).

With prolonged interaction of the virus with the macroorganism, a persistent infection (PI) occurs. Depending on the state of the body, the same virus can cause both acute and persistent infection (measles, herpes, hepatitis B, C viruses, adenoviruses). Clinical manifestations of PI can be pronounced, mild, or absent altogether; the virus can be released into the environment or not. Based on these characteristics, PIs are divided into latent (hidden infections, without virus isolation, caused by oncogenic viruses, HIV, herpes and adenoviruses); chronic (characterized by periods of remissions and exacerbations when the virus is released into the environment. Examples of chronic infections are herpes, adenovirus, chronic form of hepatitis B and C, etc.); slow (characterized by a long incubation period, slow development of symptoms leading to severe impairment of body functions and death).

Etiology of slow infections

Slow infections affecting humans and animals can be divided into 2 groups according to etiology:

Group I are slow infections caused by prions. Prions are protein infectious particles, have the form of fibrils, length from 50 to 500 nm, weighing 30 kDa. They do not contain nucleic acid, are resistant to proteases, heat, ultraviolet radiation, ultrasound and ionizing radiation. Prions are capable of reproduction and accumulation in the affected organ to gigantic levels, and do not cause CPE, immune response or inflammatory reactions. Degenerative tissue damage.

Prions cause diseases in humans:

1) Kuru (“laughing death”) is a slow infection endemic to New Guinea. It is characterized by ataxia and tremor with gradual complete loss of motor activity, dysarthria and death one year after the onset of clinical symptoms.

2) Creutzfeldt-Jakob disease, characterized by progressive dementia (dementia) and symptoms of damage to the pyramidal and extrapyramidal tracts.

3) Amyotrophic leukospongiosis, characterized by degenerative destruction of nerve cells, as a result of which the brain acquires a spongy (spongioform) structure.

Prion diseases in animals:

1) Bovine spongiform encephalopathy (mad cows);

2) Scrapie - subacute transmissible spongiform encephalopathy of Aries.

II group are slow infections caused by classical viruses.

Slow viral infections of humans include: HIV infection - AIDS (causes HIV, family Retrovoridae); PSPE - subacute sclerosing panencephalitis (measles virus, family Paramyxoviridae); progressive congenital rubella (rubella virus, family Togaviridae); chronic hepatitis B (hepatitis B virus, family Hepadnaviridae); cytomegalovirus brain damage (cytomegaly virus, family Herpesviridae); T-cell lymphoma (HTLV-I, HTLV-II, family Retroviridae); subacute herpetic encephalitis (herpes simples, family Herpesviridae), etc.

In addition to slow infections caused by viruses and prions, there is a group of nosological forms that, in clinical practice and outcome, correspond to the signs of a slow infection, but precise data on the etiology are not yet available. Such diseases include multiple sclerosis, amyotrophic lateral sclerosis, atherosclerosis, schizophrenia, etc.

Laboratory diagnosis of viral infections

The laboratory diagnosis of viral infections is based on 3 groups of methods:

1 group- Detection of the pathogen or its components directly in clinical material taken from the patient, and obtaining an answer within a few hours (fast; express diagnostics). Express diagnostic methods for the most common viral infections are given in Table. 2.

table 2

METHODS FOR EXPRESS DIAGNOSTICS OF COMMON

VIRAL INFECTIONS

Viruses	Infection	Material for research	Timing of material collection	Express diagnostic methods
Adenoviruses	Adenovirus infection	Nasopharyngeal discharge, conjunctiva, blood, feces, urine	First 7 days of illness	IF, molecular hybridization (MG), EM, ELISA, RIA
Parainfluenza, PC virus	ARVI	Nasopharyngeal discharge	The first 3-5 days of illness	IF. ELISA
Flu	Flu	Nasopharyngeal discharge	The first 3-5 days of illness	IF, IFA, RIA, EM
Rhinoviruses	ARVI	Nasopharyngeal discharge	The first 3-5 days of illness	IF
Herpes simplex	Herpes simplex	Vesicle contents	During the first 12 days after the rash appears	IF, MG, IEM, IFA
Chickenpox and herpes zoster	Chicken pox, herpes zoster	Vesicle contents	During the first 7 days after the rash appears	ELISA, IF, IEM
Cytomegaly	Cytomegalovirus infection	Urine, saliva, blood	Throughout the entire period of the disease	EM, microscopy of stained fingerprint smears, MG, IF, IgM detection
Rotaviruses	Acute gastroenteritis	Feces	The first 3-5 days of illness	EM, IEM, ELISA, RIA, MG, RNA electrophoresis in PAGE
Hepatitis A	Hepatitis A	Feces, blood	The first 7-10 days of illness	IEM, ELISA, RIA, IgM detection
Hepatitis B	Hepatitis B	Blood	The entire period of the disease	ELISA, RIA, ROPGA, MG, PCR, VIEF

2nd group methods - Isolation of the virus from clinical material, its indication and identification (virological diagnostics).

In most cases, the concentration of virus in clinical material is insufficient for rapid detection of the virus or its antigens. In these cases, virological diagnostics are used. This group of methods requires a long time, is labor-intensive, and is often retrospective. However, virological diagnosis is necessary for infections caused by new types of virus, or when diagnosis cannot be made by other methods.

For virological diagnosis, the doctor must ensure that the necessary samples of material are taken at the appropriate phase of the disease, delivered to the laboratory, providing the diagnostic laboratories with the necessary clinical information.

The material for virological research in diseases accompanied by diarrhea or other gastrointestinal disorders suggesting a viral etiology is fresh portions of feces. For diseases of the respiratory system, material for research is best obtained by aspiration of mucus and washings. Nasopharyngeal swabs are less informative. In the presence of a vesicular rash, the material for examination is the liquid aspirated from the vesicles with a needle. For petechial and maculopapular rashes, the material for research is both mucus samples from the nasopharynx and feces. If neuroviral infections are suspected, mucus from the nasopharynx, feces and cerebrospinal fluid should be collected for virological testing. The material used to diagnose mumps and rabies is saliva. If cytomegalovirus and papovirus infections are suspected, the material may be urine. An attempt to isolate the virus from the blood can be made if infections caused by certain arboviruses and herpes viruses are suspected. A brain biopsy can be performed to diagnose herpetic encephalitis, SSPE, progressive rubella panencephalitis, Kreptzfeldt-Jakob disease, leukospongiosis, etc.

Preparations of mucus from the nasopharynx or feces are placed in a transport medium consisting of saline solution with added antibiotics and a small amount of protein or animal serum. Materials can be stored at 4°C for no more than 48 hours. Longer storage requires a temperature of -70°C.

Isolation of the virus from clinical material is carried out by inoculating it into cell cultures, embryos, or infecting laboratory animals with it (see Cultivation of viruses).

The influenza virus should be isolated by inoculating virus-containing material into the ampiotic or allantoic cavity of the chick embryo. To isolate the Coxsackie A virus, rabies virus, many arboviruses, and areiaviruses, iptraperitoneal and intraperitoneal inoculation of material into newborn mice is recommended.

After infection of a cell culture, the latter is examined for the presence of CDD. Many enterovnrus cause early CDD (within a few hours). Cygomegaloviruses, adenoviruses, and rubella virus cause CPE within a few weeks, and sometimes it is necessary to resort to obtaining a subculture. The presence of sinusitis indicates the presence of viruses such as PC, measles, mumps, and herpes viruses.

Identification of viruses isolated in these systems is carried out using serological methods. Serological reactions such as RTGL, RN, PIT Ade are used only for viral infections. RSK, RPGA, ELISA, RIA, IF, RP, etc. are used to diagnose both viral infections and infections caused by other pathogens.

Diagnostics of ARVI and intestinal infections are presented in Schemes 2 and 3.

ISOLATION OF VIRUSES FROM NASOPHARYNX DISCHARGE, THEIR INDICATION AND IDENTIFICATION IN RESPIRATORY INFECTIONS

VIRAL INFECTIONS

Nasopharyngeal mucus treated with antibiotics

Chick embryo infection

Infection of suckling mice

Paralysis, death

Death, specific lesions of CAO

Coxsackie viruses, herpes

RSK, RTGA

Influenza viruses

Herpes viruses

Infection of cell culture

CPP may be absent

Syncytia education

Herpetic type of CPD

Adenoviral type of CPD

Picornaviral type of CPD

RSK, RN according to color test

IF, RN, RSK, RTGA

IF, RN, RSK

Interference

IF, RN, RTGA, RTGAds

Adenovirs

Enteroviruses, rhinoviruses

Herpes simplex viruses, cytomegaly

RS virus, measles, parainfluenza

Influenza viruses, parainfluenza, EP

Rubella virus

3 group methods - Serological diagnosis of viral infections.

A single serological test only in rare cases makes it possible to diagnose a viral disease (for example, with HIV infection). In most cases, serological diagnosis requires paired sera taken in the acute phase of the disease and after 2-4 weeks. The detection of a fourfold or more increase in antibody titer is usually considered as a diagnostic sign of an acute viral infection.

ISOLATION OF VIRUSES FROM FECES, THEIR INDICATION AND IDENTIFICATION IN INTESTINAL VIRAL INFECTIONS

Fecal suspension, treated with antibiotics, clarified by centrifugation

Infection of mice

Infection of cell cultures

Paralysis, death

Picornoviral type of CPD

Reoviral type of CPD

Adenoviral type of CPD

RN, RSK

RSK, RN according to color test

IF, RN, RTGA

RTGA, RSK, RN

Coxsackie A, B, rotaviruses

enteroviruses

Adenoviruses

Rotaviruses

Principles of therapy and prevention of viral infections

1 group- Abnormal nucleosides - analogues of nucleic acid metabolism precursors, inhibit the functions of viral polymerases or are included in the nucleic acid chain, making it non-functional.

A pyrimidine analogue, iododeoxyuridine, is used to treat herpetic keratitis, cutaneous herpes and cytomegaly. Purine analogues - vidorabide - are used to treat herpetic encephalitis, chickenpox and herpes zoster. Acyclovir (Zovirax) is also used to treat various types of herpetic infections. Ribovirin (virazol) is effective against RNA and DNA viruses. For the treatment of HIV infection, nucleoside analogs have been obtained that inhibit HIV reverse transcriptase, azidothymidine (zidovudine), timazide (phosphatide), hivid (zalcitabine).

2nd group adamantaneamine hydrochloride derivatives. Drugs: amantadine and rimantadine inhibit the reproduction of influenza, measles, red viruses

Nuhn. Most effective against influenza A. Mechanism of action: disruption of virus deproteinization.

3 group- thiosemicarbazoics. The drug metisazoi (marborap) is active against variola viruses. The mechanism of action of the drug is to suppress the synthesis of viral proteins and the assembly of viral particles.

4 group inhibitors of proteolytic activity of viruses. The essence of this phenomenon is that many proteins of picoria-, ortho-, adeno-, toga-, and retroviruses acquire viral activity only after cutting these proteins into fragments by protease enzymes. Protease inhibitors such as Gorlox, Contrical, and s-aminocaproic acid are used to treat infections caused by these viruses. In our republic, a drug from this group, invirase (saqunnavir), is used to treat HIV infection.

5 group. One of the new and promising areas of chemotherapy is the creation of drugs such as “nucleases” that can damage viral genes, which will make it possible to treat integration viral diseases.

6 group interferons. Currently, α-interferon (leukocyte IF) is used for both treatment and prevention, especially of respiratory viral infections. The mechanism of action is a violation of the synthesis of viral proteins. β-interferon or immune interferon is widely used. -interferon enhances the function of T-killers and natural killers, T-effectors of HRT. Used to treat malignant tumors and viral infections.

7 group- virus-specific immunoglobulins. which are obtained from the blood of convalescents or specially vaccinated donors. They are used to prevent measles, hepatitis A, B, influenza, parainfluenza and other viral infections (anti-rabies immunoglobudin obtained from the blood of immunized animals is used to prevent rabies). Igs interfere with virions and prevent virus adsorption on sensitive cells.

8 group- Vaccines. To prevent a number of viral infections, killed vaccines containing viruses inactivated with formalin or β-cropnolactone (vaccine against influenza, measles, polio, Japanese and tick-borne encephalitis, rabies), live (attenuated) virus vaccines containing viruses with weakened virulence ( vaccine against influenza, measles, mumps, rubella, polio, rabies, yellow fever, etc.); subunit vaccines containing viral protective antigens (subunits) (influenza vaccine); recombinant (genetically engineered) vaccines (a vaccine against hepatitis B, for the production of which the gene encoding the HBs antigen is introduced into the genome of a yeast cell). Synthetic vaccines are under development.

Laboratory diagnosis of viral hepatitis

Currently, in the category of viral hepatitis, 7 independent nosological forms are considered: hepatitis A, B, C, D, E, F, G. According to the route of transmission, viral hepatitis is divided into:

1. Enteral, transmitted by the fecal-oral route. These include hepatitis A, E and, obviously, F.

2. Parenteral, transmitted through parenteral manipulation, including, under natural conditions, transplacental and sexual transmission. These include hepatitis B, C, D, G.

The most widespread are hepatitis A, B, C, the comparative characteristics of which are presented in table. 3.

Table 3

COMPARATIVE CHARACTERISTICS

VIRAL HEPATITIS A, B, C

Sign	Hepatitis A	Hepatitis B	Hepatitis C
Virus (family)	Picomaviridae	Hepadnaviridae	Flaviviridae
Nucleic acid type	single-stranded +RNA	double-stranded DNA with a single-stranded region	single-stranded +RNA
Virion size	27-32 nm	42-45 nm	30-60 nm
Supercapsid	absent	available	available
Path of infection	fecal-oral	parenteral	parenteral
Incubation period	on average 25-30 days	on average 60-90 days, maybe up to 6 months	on average 35-70 days
Age groups	mainly children under 1 5 years old	children and adults	children and adults
Seasonality	mostly August-September	during the whole year	throughout the whole Gogi
Transition to chronic form	absent	occurs	takes place in 50% of cases
Carriage	absent	long-term	long-term
Oncogenicity	absent	occurs	occurs

I. Hepatitis A (hA). Laboratory diagnosis of hepatitis A is based either on identifying the pathogen itself (immune electron microscopy method - IEM), its antigens (radioimmune, enzyme immunoassay, immunofluorescent method - RIA, ELISA, IF) or antibodies to the hepatitis A virus (RIA, ELISA).

For early diagnosis of the disease, as well as identifying sources of infection, the determination of the antigen of the hepatitis A virus in the feces of patients is used, where it appears 7-10 days before clinical symptoms and in the first days of the disease.

Of the currently determined specific markers of hepatitis A, the most important are Ig M antibodies to the hepatitis A virus, which appear in the blood serum and saliva at the onset of the disease and persist for 3-6 months. The detection of Ig M class antibodies to the hepatitis A virus clearly indicates hepatitis A and is used to diagnose the disease, including asymptomatic cases of infection, and to identify sources of infection in foci.

Antibodies to the hepatitis A virus of the Ig G class are detected from the 3-4th week of the disease and persist for a long time, which makes it possible to assess the state of the population’s immunity and the dynamics of specific humoral immunity.

Hepatitis A virus in material from a patient can be detected by immune electron microscopy. The method is based on mixing a virus suspension with antiserum, separating immune complexes and examining them in an electron microscope.

II.Hepatitis B (hB). In the body of people infected with the hepatitis B virus, serological markers can be detected at different frequencies and at different stages: surface HBs Ag and core HBe Ag, as well as antibodies to them (anti-HBc, anti-HBe, anti-HBs). The dynamics of their appearance and interpretation of the results are presented in Table. 4 and 5.

Table 4

SEROLOGICAL MARKERS IN HEPATITIS B

Table 5

INTERPRETATION OF SEROLOGICAL MARKERS IN HEPATITIS B

Antigens		Antibodies to HBs-Ar	Antibodies kNVs-Ag		Interpretation
BHs	НВе		fgG	IgM
+	+	–	–	+	Acute phase of hepatitis
+	±	–	+	–	Chronic hepatitis B
+	–	–	–	–	Carriage
–	–	+	–	–	Hepatitis B in the past
–	–	–	–	–	No history of hepatitis B

All antigens and their corresponding antibodies can serve as indicators of the infectious process.

The presence of viral DNA, HBs Ag, HBe Ag and anti-HBc class Ig M indicates an acute period of infection. During the period of convalescence, these are anti-HBc antibodies of the Ig G class and they are detected together with anti-Hbs antibodies. The prolonged presence of HBs-Ag, HBe-Ag and anti-HBc (IgG) in the blood is an unfavorable sign indicating the formation of a chronic process.

During the formation of long-term carriage, HBs Ag is constantly determined. To detect antigens and antibodies, RPGA, RIA and ELISA are used. To detect HBs Ag, ROPHA is used - a reverse passive hemagglutination reaction with a mandatory positive control for HBs Ag.

III. Hepatitis C (hC).Caused by an RNA virus that belongs to the Flaviviridae family. The diameter of virions is 30-60 nm, sensitive to treatment with chloroform. Positive single-stranded RNA encodes the synthesis of three structural and five non-structural proteins. Hepatitis C is similar in clinical and biochemical characteristics to hepatitis B. In 60% of infected individuals, the disease becomes chronic, and 20% of chronic patients develop cirrhosis of the liver. The mechanism of transmission of the hepatitis C virus is mainly parenteral. Laboratory diagnosis of hepatitis C is based on the determination of antibodies to the hepatitis virus using ELISA or RIA methods.

IV. The causative agent of hepatitis delta (hepatitis D).An RNA-containing, defective virus that can resolve itself in the host’s body only with the obligatory participation of a helper virus, the role of which is played by the hepatitis B virus. The envelope of the delta virus is formed by HBs Ag. The addition of delta infection to hepatitis B leads to the development of severe malignant forms of the disease, chronic forms of the disease with the early formation of liver cirrhosis.

Laboratory diagnosis of hepatitis D is carried out by detecting markers of the hepatitis B virus and delta virus infection, HBs Ag, anti-HBc (Ig M) and delta Ag. The latter are tested using ELISA and RIA. Anti-delta Ig M, which are detected throughout the disease, are of greatest diagnostic importance.

V. Hepatitis E. Widely distributed in tropical and subtropical countries, the spread of the disease occurs by water. The virion, 27-32 in diameter, contains single-stranded RNA and is similar in physicochemical properties to viruses of the Calicivmdae family. Laboratory diagnosis is based on the determination of AT in blood serum by ELISA.

VI. Hepatitis G. The hepatitis G virus was discovered in 1995, classified in the Flaviviridae family, transmitted parenterally. The size of the virion is 20-30 nm. The genome of the virus is represented by single-stranded + RNA. The capsid protein is defective or not synthesized at all. Therefore, it is assumed that the hepatitis G virus uses either proteins from undiscovered viruses or cellular proteins for its capsid. There are indications of the presence of a lipid membrane in the virus. The marker of virus replication is its RNA. Antibodies against the E 2 protein of the hepatitis G virus are detected only in the absence of viral RNA. This indicates that, unlike hepatitis C, detection of antibodies in hepatitis G cannot be used to search for virus carriers, but is suitable for registering a past infection.

VII. Hepatitis F. The hepatitis F virus was discovered by French scientists and has not actually been studied.

Laboratory diagnosis of HIV infection

When diagnosing HIV infection, 4 groups of methods are used:

1. Determination of the presence of the virus, its antigens or RNA copies in materials from a patient or HIV-infected person

2. Serological diagnosis, based on the detection of specific antibodies to surface (gp 120 and gp 41) and internal (p 18 and p 24) HIV proteins.

3. Identification of pathognomonic (specific) changes in the immune system for HIV infection.

4. Laboratory diagnosis of opportunistic infections (AIDS-associated diseases).

1. Virological diagnosis. The material for isolating HIV is blood T-lymphocytes, bone marrow leukocytes, lymph nodes, brain tissue, saliva, sperm, cerebrospinal fluid, and blood plasma. The resulting material is used to infect a continuous culture of T-lymphocytes (H9). Indication of HIV in cell culture is carried out by CPD (formation of symplasts), as well as by immunofluorescence, electron microscopy, and expressed reverse transcriptase activity. Modern research methods make it possible to detect one infected lymphocyte per 1000 cells.

Detection of viral antigens in infected T lymphocytes is carried out using monoclonal antibodies

In recent years, determining the number of copies of HIV RNA in the blood plasma using the polymerase chain reaction (PCR) method - the so-called viral load - has been crucial for determining the prognosis and severity of HIV infection. If in patients not receiving therapy, the viral load is below the detection limit (less than 5000 copies of HIV RNA in 1 ml of plasma), this indicates the absence of progression or slow progression. The degree of contagion is minimal. A high viral load (more than 10,000 copies of RNA in 1 ml of plasma) in patients with a number of CO4 lymphocytes less than 300 in 1 μl always indicates progression of the disease.

2. Serological diagnosis. Currently it is most widespread.

Material for research: 5 ml. heparinized blood, which can be stored refrigerated, but not frozen, for 6-8 hours before delivery to the laboratory.

For the purpose of serological diagnosis of AIDS, primarily enzyme immunoassay methods with standard enzyme immunoassay systems (ELISA) are used. This is a screening method. The operating principle is based on the classic principle of direct ELISA. The immunosorbent is polystyrene tablets with immobilized inactivated virus-specific antigen obtained from HIV or synthetically. Then the diluted test serum is added. Incubation is carried out in wells with antigen. After the binding of AG to AT, unbound proteins are washed three times, and then a conjugate of antibodies to human immunoglobulins with an enzyme label is added to the wells. The formation of a specific AG+AT complex is detected by adding a substrate for the enzyme (a solution of orthophenylenediamine and hydrogen peroxide). As a result, the color of the medium changes in proportion to the amount of antibodies. The results of the study are taken into account on a spectrophotometer. Blood sera that have virus-specific antibodies according to ELISA data must be further examined by immunoblotting.

Immune blotting is a confirmatory test because it detects antibodies to various HIV proteins. It is based on preliminary fractionation by molecular weight (separation) of HIV proteins by electrophoresis in a polyacrylamide gel, followed by transfer of antigens to a nitrocellulose membrane. The test serum is then applied to the membrane. In this case, specific antibodies form a complex with a specific antigen (gp.120, gp.41, p.24, p.18). The final stage of the study is the identification of antibodies to various HIV proteins. To do this, antibodies against human proteins labeled with an enzyme or radioisotope label are added to the system. Thus, virus-specific antibodies to all or most HIV antigens are detected (or not detected) in the patient’s serum.

3. Studies of immune status. Aimed at identifying:

1) reducing the ratio of CD4/CD8 cells (in N 2 and >, with AIDS - 0.5 and
2) reducing the content of CD4 cells (
3) the presence of one of the laboratory signs, including anemia, leukopenia, thrombopenia, lymphopenia;

4) increasing the concentration of Ig A and Ig G in the blood serum;

5) reducing the response of lymphocyte blast formation to mitogens;

6) absence of skin reaction of GTZ to several antigens;

7) increasing the level of circulating immune complexes.

DEVELOPMENT OF TUMORS, OPPORTUNISTIC INFECTIONS AND INVASIONS IN HIV INFECTION

CNS cells

T helper cells

Encephalopathy dementia

Violation of GMOs and CIOs

Dysfunction of T-killer cells

Ontogenesis

Kaposi's sarcoma, brain lymphoma

Opportunistic infections, infestations caused by

Viruses

The simplest

Bacteria

Helminths

• 
  Herpes simplex type I and II;
• 
  Herpes zoster;
• 
  Cytomegalovirus;
• 
  Epstein-Barr virus;

General virology studies the nature of viruses, their structure, reproduction, biochemistry, and genetics. Medical, veterinary and agricultural virology studies pathogenic viruses, their infectious properties, develops measures for the prevention, diagnosis and treatment of diseases caused by them.

Virology solves fundamental and applied problems and is closely related to other sciences. The discovery and study of viruses, in particular bacteriophages, made a huge contribution to the formation and development of molecular biology. The branch of virology that studies the hereditary properties of viruses is closely related to molecular genetics. Viruses are not only a subject of study, but also a tool for molecular genetic research, which connects virology with genetic engineering. Viruses are the causative agents of a large number of infectious diseases in humans, animals, plants, and insects. From this point of view, virology is closely related to medicine, veterinary medicine, phytopathology and other sciences.

Having emerged at the end of the 19th century as a branch of human and animal pathology, on the one hand, and phytopathology, on the other, virology became an independent science, rightfully occupying one of the main places among the biological sciences.

Virology is a young science, its history goes back a little over 100 years. Having begun its journey as the science of viruses that cause diseases in humans, animals and plants, virology is currently developing in the direction of studying the basic laws of modern biology at the molecular level, based on the fact that viruses are part of the biosphere and an important factor in the evolution of the organic world.

HISTORY OF VIRUSOLOGY

The history of virology is unusual in that one of its subjects - viral diseases - began to be studied long before viruses themselves were discovered. The beginning of the history of virology is the fight against infectious diseases and only subsequently the gradual disclosure of the sources of these diseases. This is confirmed by the work of Edward Jenner on the prevention of smallpox and the work of Louis Pasteur with the causative agent of rabies.

By the end of the 19th century, it became clear that a number of human diseases, such as rabies, smallpox, influenza, and yellow fever, are infectious, but their causative agents were not detected by bacteriological methods.

Thanks to the work of Robert Koch, who was the first to use the technique of pure bacterial cultures, it became possible to distinguish between bacterial and non-bacterial diseases. In 1890, at the X Congress of Hygienists, Koch was forced to declare that “... with the diseases listed, we are not dealing with bacteria, but with organized pathogens that belong to a completely different group of microorganisms.” This statement by Koch indicates that the discovery of viruses was not a random event. Not only the experience of working with pathogens that were incomprehensible in nature, but also an understanding of the essence of what was happening contributed to the formulation of the idea of ​​the existence of an original group of pathogens of infectious diseases of a non-bacterial nature. It remained to experimentally prove its existence.

For a certain period of time, in foreign publications, the discovery of viruses was associated with the name of the Dutch scientist Beijerinck, who also studied tobacco mosaic disease and published his experiments in 1898. Beijerinck placed the filtered juice of an infected plant on the surface of agar, incubated it, and obtained bacterial colonies on its surface. . After this, the top layer of agar with bacterial colonies was removed, and the inner layer was used to infect a healthy plant. The plant is sick. From this, Beijerinck concluded that the cause of the disease was not bacteria, but some liquid substance that could penetrate inside the agar, and called the pathogen “liquid living contagion.” Due to the fact that Ivanovsky only described his experiments in detail, but did not pay due attention to the nonbacterial nature of the pathogen, a misunderstanding of the situation arose. Ivanovsky’s work became famous only after Beijerinck repeated and expanded his experiments and emphasized that Ivanovsky was the first to prove the non-bacterial nature of the causative agent of the most typical viral disease of tobacco. Beijerinck himself recognized the primacy of Ivanovsky and the current priority of the discovery of viruses by D.I. Ivanovsky is recognized throughout the world.

The word VIRUS means poison. This term was also used by Pasteur to denote an infectious principle. It should be noted that at the beginning of the 19th century, all pathogenic agents were called the word virus. Only after the nature of bacteria, poisons and toxins became clear, the terms “ultravirus” and then simply “virus” began to mean “a new type of filterable pathogen.” The term “virus” took root widely in the 30s of our century.

Viruses are a unique class, the smallest class of infectious agents that pass through bacterial filters and differ from bacteria in their morphology, physiology and method of reproduction.

Viruses are extracellular life forms, the super-kingdom of the Nuclear-Free (accaryotes), the kingdom of Vir.

It is now clear that viruses are characterized by ubiquity, that is, ubiquity of distribution. Viruses infect representatives of all living kingdoms: humans, vertebrates and invertebrates, plants, fungi, bacteria.

NATURE OF VIRUSES

Viruses are extracellular life forms.

Viruses are the smallest infectious agents

Reproduction method. Viruses do not reproduce by fission; viral reproduction is reproduction - the assembly of individual viral components into a viral particle.

Viruses occur in nature in two states: outside the cell, the viral particle is in the form of a virion - the structure of the virus in which all the main viral components can be detected; Inside the cell, the virus is in a vegetative form - it is a replicating viral nucleic acid.

Viruses cannot reproduce in ordinary nutrient media, but only in cells, tissues or organisms.

Chemical composition. The viral particle has a protein shell - a protein, one type of nucleic acid, either RNA or DNA, and also an ash component. Complex viruses also have capsids and carbohydrates.

Structure of nucleic acid (NA). NK viruses (RNA or DNA) are guardians of genetic information. Viruses contain atypical forms of NA - double-stranded RNA and single-stranded DNA.

Viral particles do not grow.

VIRUS SIZES

Viruses are the smallest agents, nm (0.01-0.35 microns). They are not visible with a regular light microscope, and various methods are used to determine the size of viruses:

1. filtration through filters with known pore sizes;

2. determination of the sedimentation rate of particles during centrifugation;

3. photography in an electron microscope.

CHEMICAL COMPOSITION OF VIRUSES

Viruses have three main components: protein, NK, and ash component.

Proteins are built from amino acids (a/k) of the L-series. All a/c are of trivial nature; as a rule, neutral and acidic dicarboxylic acids predominate in the structure. Complex viruses contain basic histone-like proteins associated with NK to stabilize the structure and increase antigenic activity.

All viral proteins are divided into: structural - form the protein shell - capsid; functional - enzyme proteins, some of the enzyme proteins are located in the structure of the capsid, these proteins are associated with enzymatic activity and the ability of the virus to penetrate into the cell (for example, ATPase, sialase - neiromeidase, which are found in the structure of the human and animal virus, as well as lysozyme).

The capsid consists of long polypeptide chains that may consist of one or more proteins with a small molecular weight. In the structure of the polypeptide chain, chemical, structural and morphological units are distinguished.

A chemical unit is a single protein that forms a polypeptide chain.

A structural unit is a repeating unit in the structure of a polypeptide chain.

The morphological unit is the capsomere, which is observed in the structure of the virus, which is visible in an electron microscope.

Viral capsid proteins have a number of properties: they are resistant to proteases and the reason for resistance is that the protein is organized in such a way that the peptide bond on which the protease acts is hidden inside. Such stability has a great biological meaning: since the viral particle is collected inside the cell, where the concentration of proteolytic enzymes is high. This stability protects the viral particle from destruction inside the cell. At the same time, this resistance of the viral envelope to proteolytic enzymes is lost when the viral particle passes through the cell membrane, in particular through the CPM.

It is assumed that during the transport of the viral particle through the CPM, changes in the conformational structure occur and the peptide bond becomes accessible to enzymes.

Functions of structural proteins:

Protective (protect the NK, which is located inside the capsid);

Some capsid proteins have a targeting function, which is considered as viral receptors, with the help of which the viral particle attaches to the surface of specific cells;

An internal histone-like protein associated with NK was found in the virions, which has an antigenic function and is also involved in the stabilization of NK.

Functional enzyme proteins associated with the capsod:

Sialase-neuromyedase. Found in animal and human viruses, it facilitates the exit of the viral particle from the cell and makes a hole (bald patch) in the viral structures;

Lysozyme. Structurally related to the viral particle, it destroys the β-1,4-glycosidic part in the murein framework and facilitates the penetration of bacteriophage NK into the bacterial cell.

ATPase. Built into the structure of bacteriophage and some human and animal viruses of cellular origin. The functions were studied using the example of bacteriophages; with the help of ATPase, ATP is hydrolyzed, which are intercalated into the structure of the virus and are of cellular origin, the released energy is consumed by contraction of the tail process, this facilitates the transport of NK into the bacterial cell.

The molecular weight of viral DNA varies by D, while that of RNA varies less than D.

The NK of viruses is 10 times smaller than the NK of the smallest cells.

The number of nucleotides in DNA varies from several thousand to 250 thousand nucleotides. 1 gene – 1000 nucleotides, this means that in the structure of viruses there are from 10 to 250 genes.

In the composition of NK, along with five nitrogenous bases, there are also abnormal bases - bases that are fully capable of replacing standard ones: 5-hydroxymethylcytosine - completely replaces cytosine, 5-hydroxymethyluracil - replaces thymine.

Anomalous bases are found only in bacteriophages; the rest have classical bases.

Functions of abnormal bases: block cellular DNA, preventing the information contained in the DNA from being realized at the moment when the viral particle enters the cell.

In addition to abnormal ones, minor bases were also found: a small amount of 5-methylcytosine, 6-methylamino purine.

Some viruses may contain methylated derivatives of cytosine and adenine.

NK viruses, both RNA and DNA, can be found in two forms:

In the form of ring chains;

In the form of linear molecules.

Covalently closed chains (do not have 3' - 5' free ends, exonucleases do not act on them);

Relaxed form, when one chain is covalently closed, and the second has one or more breaks in its structure.

Linear molecules are divided into two groups:

Linear structure with a fixed sequence of nucleotides (always begins with one nucleotide);

Linear structure with a permitted sequence (a certain set of nucleotides, but the sequence is variable).

The structure of RNA contains single-stranded +RNA and −RNA chains.

RNA is, on the one hand, the keeper of genetic information, and on the other hand, it performs the function of mRNA and is recognized by the ribosomes of the cell as mRNA.

−RNA − perform only the function of storing genetic information, and mRNA is synthesized on its basis.

Viral particles contain metal cations: potassium, sodium, calcium, manganese, magnesium, iron, copper, and their content can reach several mg per 1 g of viral mass.

Me2+ functions: play an important role in stabilizing the viral NK, forming an ordered quaternary structure of the viral particle. The composition of metals is not constant and is determined by the composition of the environment. Some viruses have polycations associated with polyamines, which play a huge role in the physical stability of viral particles. Also, metal ions provide neutralization of the negative charge of NCs, which form phosphoric acid (phosphate groups) of NCs.

V. occupies a significant place in biology and medicine, since viruses cause many diseases in humans, animals, and plants; they affect mold fungi, protozoa, and bacteria, and also due to the fact that the main problems of genetics and molecular science are studied using the model of viruses. biology.

Story

The founder of V. is the Russian scientist D.I. Ivanovsky. Studying tobacco mosaic disease and using the filtration method, he established in 1892 that the filtrate from a ground suspension of leaves affected by this disease did not contain microorganisms visible under a microscope, but caused typical signs of mosaic disease in healthy plants. Based on these experiments, Ivanovsky concluded that tobacco mosaic disease is caused by tiny microorganisms passing through ceramic filters that retain all bacteria known at that time, that they are not able to grow on artificial nutrient media used in bacteriology, and are transmitted in a series of successive passages ( vaccinations). In 1902, Ivanovsky discovered crystalline inclusions in the cells of tobacco plants affected by mosaic disease; later other scientists confirmed that this was an accumulation of viral particles.

The use of the filtration method made it possible to subsequently establish the passage of pathogens of other known human and animal diseases through ceramic filters: foot and mouth disease [F. Leffler and Frosch (P. Frosch), 1898], yellow fever [Reed (W. Reed, 1901) et al.]. In 1911, F. Rous proved the viral etiology of chicken sarcoma, i.e., he was the first to experimentally establish that viruses can cause neoplastic processes.

To study viruses that infect animals and plants, relevant animal and plant species were used as models. To study and isolate viruses that cause human diseases, laboratory animals susceptible to this virus (mice, rats, guinea pigs, rabbits, ferrets, etc.) were used. Techniques for introducing various infectious materials into the cornea, skin, brain, and respiratory tract, as well as the principle of repeated passages in various animal species, were widely used. Thus, using experimental animals, the viruses of rabies, smallpox, herpes, foot-and-mouth disease, influenza, encephalitis, poliomyelitis, choriomeningitis, etc. were isolated and studied. However, by the end of the 30s, the possibilities of this method were exhausted, since it was not possible to isolate many viruses , experimental animals were immune to Crimea, or it was impossible to obtain a large number of viruses purified from tissue elements and in high concentrations.

In 1931, a method for cultivating viruses on 8-13-day chicken embryos was proposed by M. F. Woodruff and E. Goodpasture. In the 40s, the method became widespread in virology, because it had a number of advantages: ease of use, greater sensitivity, the possibility of accumulating large amounts of virus, relative tightness that protects against contamination, relative ease of purification from impurities, the ability to quickly determine the presence of a virus in embryonic fluids according to the hemagglutination reaction.

Using the method of cultivation in the chicken embryo (in the cells of the amniotic membrane, in individual organs of the embryo and cells of the yolk sac), viruses of human and animal influenza, fowl plague, cowpox, human herpes, equine encephalomyelitis, etc. were studied. Enders, Robbins, Weller (J. F. Enders , F. S. Robbins, T. H. Weller, 1948-1952) used the method of cell and tissue cultures to isolate and study viruses. This method became widely used in various virological studies and over the course of several years enriched science not only with the discovery of hundreds of previously unknown viruses, but also expanded the possibilities for the production of higher-quality viral vaccines and diagnostic drugs; the tissue culture method has opened up new opportunities for studying various aspects and stages of the process of interaction between a virus and a cell (see Cultivation of viruses, Cell and tissue cultures).

Further progress of viruses, and in particular the study of the structure, physiology, biochemistry and genetics of viruses, depended on obtaining them in concentrated and purified form and was associated with the introduction of new physical-chemical. research methods: differential and gradient centrifugation, molecular adsorption and ion exchange chromatography, electrophoresis on paper and in polyacrylamide gel, radioactive isotopes and a number of others.

V.'s rapid progress was due to the use of electron microscopes with high resolution (up to 1.0-0.5 nm, in combination with methods of shading and double shading, ultrathin sections, positive and negative contrast, as well as autoradiography, cytochemistry and immunochemistry. The use of a set of these methods made it possible to study the structural organization of virions of various viruses, to propose a new classification of viruses based on their structure and biochemical composition, to study the patterns of virus reproduction and to determine the details of their ontogenesis, to characterize the main parameters of subviral components (nucleic acids, proteins, etc.). etc.), begin in-depth research on the genetics of viruses and begin to develop rational approaches to chemotherapy for viral infections.

V.'s development contributed to the study and solution of general biology. problems: proving the genetic function of nucleic acids, deciphering the genetic code, understanding the most important mechanisms for regulating the synthesis of cellular macromolecules, establishing the transfer of information from cell to cell, etc.

Practical healthcare has received a number of reliable vaccines for the specific prevention of not only smallpox, which was known long before the birth of V. as a science, but also yellow fever, polio, and measles; new agents have appeared for nonspecific effects on viral infections, for example, interferon (see).

Main directions of modern virology

The main directions of modern general and medical. virology: further study of the fine structure of viruses, their biochemistry and genetics, replication of viral nucleic acids, interaction of the virus with the cell, in-depth study of antiviral immunity, improvement of methods for isolating viruses and diagnosing viral diseases, developing the fundamentals of chemotherapy and chemoprevention of viral infections; studying the ecology of viruses, developing more advanced methods of prevention, searching and testing drugs for the treatment of viral diseases.

Particular attention will be focused on the study of viruses that cause neoplastic processes, as well as latent viral infections and latent viral carriage, the search for pathogens of infectious and serum hepatitis, and the development of influenza prevention.

In the 30s, the first virological laboratories were created in the USSR: for the study of plant viruses - at the Ukrainian Institute of Plant Protection (1930), for the study of animal viruses - at the Institute of Experimental Veterinary Medicine in Moscow in 1930 (N. F Gamaleya), Central Virology Laboratory of the People's Commissariat of Health of the RSFSR in Moscow (L. A. Zilber) and the Department of Virology at the Institute of Epidemiology and Microbiology named after. L. Pasteur in Leningrad (A. A. Smorodintsev) in 1935. In the post-war years, specialized research, scientific-production and practical institutions were created and operate in the USSR. According to data as of January 1, 1973, in the USSR, research in general and medical. V. were carried out in 60 scientific, research and production institutions and educational institutions. The most significant: Institute of Virology named after. D.I. Ivanovsky of the USSR Academy of Medical Sciences, Institute of Poliomyelitis and Viral Encephalitis of the USSR Academy of Medical Sciences, Institute of Epidemiology and Microbiology named after. N. F. Gamaleyi of the USSR Academy of Medical Sciences, Institute of Experimental and Clinical Oncology of the USSR Academy of Medical Sciences, Institute of Molecular Biology of the USSR Academy of Sciences, Institute of Microbiology of the USSR Academy of Sciences, All-Union Institute of Influenza M3 USSR, Moscow Research Institute of Viral Preparations M3 USSR, Sverdlovsk Research Institute of Viral Infections M3 RSFSR, Institute of Virology and Microbiology of the Academy of Sciences of the Ukrainian SSR, Odessa Research Institute of Virology and Epidemiology named after. I. I. Mechnikova M3 of the Ukrainian SSR, Institute of Infectious Diseases M3 of the Ukrainian SSR, Institute of Microbiology named after. A. Kirchenshtein of the Academy of Sciences of the Latvian SSR; Virology laboratories and departments have been created in all research institutes of microbiology and epidemiology of the Union republics.

The largest foreign institutions conducting scientific research in general and medical fields. V.: National Institute for Medical Research (London), National Communicable Disease Center (Atlanta, USA), National Institute of Health (Tokyo), National Institute of Health (Bethesda, USA), Institute of Epidemiology and Microbiology (Prague), Institute of Virology (Bratislava), Institute Pasteur (Paris), Institute Inframicrobiology (Bucharest), Institute of Virology (Glasgow, England), State Institute of Hygiene (Budapest), Virus Research Center (Pune, India), Queensland Institute of Medical Research ( Brisbane, Australia).

Results of scientific research in general and medical sciences. V. are published in the following scientific journals: Reports of the USSR Academy of Sciences (Moscow), Bulletin of Experimental Biology and Medicine (Moscow), Questions of Virology (Moscow), Journal of Microbiology, Epidemiology and Immunology (Moscow), Bulletin of the USSR Academy of Medical Sciences (Moscow), Archiv fur die gesamte Virusforschung (Vienna), Acta Virologica (Prague), Virology (New York), Ann. Institute Pasteur (Paris), Revue Romanine de Virologie (Bucharest), Inter. Journal of Cancer (Helsinki), Journal of Virology (Washington), Advances Virus Research (Pittsburgh, USA), Journal of the National Cancer Institute (Bethesda, USA), Intervirology (Bern).

In 1950, the Council of Ministers of the USSR established the Prize named after. D. I. Ivanovsky, awarded by the USSR Academy of Medical Sciences every three years for the best work in the field of V. In recent years, the following scientists have been awarded this prize: in 1969 - V. M. Zhdanov and S. Ya. Gaidamovich for the manual “Virology” "; in 1973 - V. D. Solovyov and T. A. Bektemirov for the monograph “Interferon in the theory and practice of medicine.”

The first monographs on virology: Rivers T., Filterable Viruses, Baltimore, 1928; Hauduroy P., Les Ultra Virus, Paris, 1929; Gamaleya N. F. Filterable viruses, M., 1930.

The results of scientific research on V. are discussed at conferences, sessions held by specialized institutes, and also at international congresses.

In the USSR, the first scientific conference on viral plant diseases took place in March 1935 in Kharkov, the first scientific conference on ultramicrobes, filterable viruses and bacteriophages - in December 1935 in Moscow. In 1966, the International Committee on Virus Nomenclature was elected for the first time at the 9th International Congress of Microbiology.

The 1st International Congress on Virology was held in 1968 in Helsinki, the 2nd in 1971 in Budapest (the charter of the section of virologists established within the framework of the International Association of Microbiologists was adopted), the 3rd in 1975 in Madrid .

The development of V. led to the discovery of new viruses, the number of which quickly increased, and therefore collections of viruses were created - museums where viruses isolated both in a given country and obtained from other countries were stored. The largest collections of viruses: in the USSR (Moscow, Institute of Virology of the USSR Academy of Medical Sciences) - State Collection of Viruses, founded in 1956 as a branch of the All-Union Museum of Living Cultures and Opportunistic Microorganisms; in the USA (Washington) - a collection of viruses and rickettsia, founded in 1959 on the basis of a collection of type cultures (American type culture collection, Washington 7, Rockville, Maryland, USA); in Czechoslovakia (Prague, Institute of Epidemiology and Microbiology) - Czechoslovak National Collection of Type Cultures, founded in 1969 (Czechoslovak National collection of type cultures of the Institute Epidemiology and Microbiology, Prague); in Japan (Tokyo) - Japanese collection of microorganism cultures, founded in 1962 (The Japanes Federation of Culture collection of Microorganisms, Tokyo, Japan); in England (London) - catalog of the national collection of type cultures, founded in 1936 (Medical Research Council, Catalog of the National collection of Type cultures, London, England); in Switzerland (Lausanne, International Center for Living Cultures) there is an international catalog of viruses.

Teaching V. in medical. Universities of the USSR are conducted by the departments of microbiology in the 2nd and 3rd years, and lectures and clinical classes on viral infections are conducted by the departments of infectious diseases in the 5th year.

At the biological sciences departments of Moscow and Kyiv universities, V. departments have been created over the past 10 years, where they train virologists and teach V. for one semester to students of other departments.

Progress honey. V. in the USSR was accompanied by an increase in the number of highly qualified specialists: from 1946 to 1960, 16 doctors of sciences were prepared, from 1961 to 1972 - 140, candidates of sciences, respectively, 217 and 836 (of which 54% were trained in graduate school). The V. Department at the Central Research University, created in 1955, played an important role in the training of virologists (specialization and improvement). It trained 688 specialists from October 1955 to 1964, and from 1965 to January 1974. - 933, ch. arr. to ensure virological work in sanitary-epidemiological stations.

Bibliography: Avakyan A. A. and Bykovsky A. F. Atlas of anatomy and ontogenesis of human and animal viruses, M., 1970, bibliogr.; Rabies, ed. V. D. Solovyova, M., 1954, bibliogr.; Gavrilov V.I., Semenov B.F. and Zhdanov V.M. Chronic viral infections and their modeling, M., 1974, bibliogr.; Gamaleya N. F. Filterable viruses, M.-L., 1930; Gendon Yu. 3. Genetics of human and animal viruses, M., 1967, bibliogr.; Zhdanov V. M. and Gaida mo-vich S. Ya. Virology, M., 1966; Zhdanov V.M., Soloviev V.D. and Epstein F.G. Doctrine of influenza, M., 1958; Zilber L. A. The doctrine of viruses (general virology), M., 1956; Ivanov-k and y D.I. About two diseases of tobacco, Agricultural. and forestry, vol. 169, no. 2, p. 104, 1892; Kosyakov P. N. and P about in N about in and 3. I. Antiviral immunity, M., 1972; Morozov M. A. and Soloviev V. D. Smallpox, M., 1948; Pershin G. N. and B ogdanova N. S. Chemotherapy of viral infections, M., 1973, bibliogr.; With o-lovyev V.D. Spring-summer tick-borne encephalitis, M., 1944, bibliogr.; With o-lovyev V.D. and Balandin PI. G. Biochemical principles of interaction between virus and cell, M., 1969, bibliogr.; they, Cell and Virus, M., 1973, bibliogr.; Soloviev V.D. and Bek-temirov T.A. Interferon in the theory and practice of medicine, M., 1970, bibliogr.; Tikhonenko T. I. Biochemistry of viruses, M., 1965, bibliogr.; Sh u b l a d - e A. K. and G a i d a m o v i h S. Ya. Short course of practical virology, 2nd ed., M., 1954; Shubladze A.K., Bychkova E.N. and Barinsky I.F. Viremia in acute and chronic infections, M., 1974; Comprehensive virology, ed. by H. Fraenkel-Conrat a. R. R. Wagner, v. 1 - 4, N.Y., 1974, bibliogr.; Starke G.u. HlinakP. Grundriss der allgemeinen Virologie, Jena, 1974, Bibliogr.

V. D. Solovyov, A. M. Zhukovsky.

Introduction

General virology studies the nature of viruses, their structure, reproduction, biochemistry, and genetics. Medical, veterinary and agricultural virology studies pathogenic viruses, their infectious properties, develops measures for the prevention, diagnosis and treatment of diseases caused by them.

Virology solves fundamental and applied problems and is closely related to other sciences. The discovery and study of viruses, in particular bacteriophages, made a huge contribution to the formation and development of molecular biology. The branch of virology that studies the hereditary properties of viruses is closely related to molecular genetics. Viruses are not only a subject of study, but also a tool for molecular genetic research, which connects virology with genetic engineering. Viruses are the causative agents of a large number of infectious diseases in humans, animals, plants, and insects. From this point of view, virology is closely related to medicine, veterinary medicine, phytopathology and other sciences.

Having emerged at the end of the 19th century as a branch of human and animal pathology, on the one hand, and phytopathology, on the other, virology became an independent science, rightfully occupying one of the main places among the biological sciences.

Chapter 1. History of virology

1.1. Virus discovery

Virology is a young science, its history goes back a little over 100 years. Having begun its journey as the science of viruses that cause diseases in humans, animals and plants, virology is currently developing in the direction of studying the basic laws of modern biology at the molecular level, based on the fact that viruses are part of the biosphere and an important factor in the evolution of the organic world.

The history of virology is unusual in that one of its subjects - viral diseases - began to be studied long before viruses themselves were discovered. The beginning of the history of virology is the fight against infectious diseases and only subsequently the gradual disclosure of the sources of these diseases. This is confirmed by the work of Edward Jenner (1749-1823) on the prevention of smallpox and the work of Louis Pasteur (1822-1895) with the causative agent of rabies.

Since time immemorial, smallpox has been the scourge of humanity, claiming thousands of lives. Descriptions of smallpox infection are found in the manuscripts of ancient Chinese and Indian texts. The first mention of smallpox epidemics on the European continent dates back to the 6th century AD (an epidemic among the soldiers of the Ethiopian army besieging Mecca), after which there was an inexplicable period of time when there were no mentions of smallpox epidemics. Smallpox began to spread across continents again in the 17th century. For example, in North America (1617-1619) in the state of Massachusetts, 9/10 of the population died, in Iceland (1707) after a smallpox epidemic, only 17 thousand remained from 57 thousand people, in the city of Eastham (1763) ) from 1331 inhabitants there are 4 people left. In this regard, the problem of combating smallpox was very acute.

A technique for preventing smallpox through vaccination, called variolation, has been known since ancient times. Mentions of the use of variolation in Europe date back to the mid-17th century, with references to earlier experience in China, the Far East, and Turkey. The essence of variolation was that the contents of pustules from patients suffering from a mild form of smallpox were introduced into a small wound on the human skin, which caused a mild disease and prevented an acute form. However, there remained a high risk of contracting a severe form of smallpox and the mortality rate among vaccinated people reached 10%. Jenner revolutionized smallpox prevention. He was the first to notice that people who had cowpox, which was mild, never subsequently suffered from smallpox. On May 14, 1796, Jenner introduced liquid from the pustules of milkmaid Sarah Selmes, who had cowpox, into the wound of James Phipps, who had never suffered from smallpox. At the site of the artificial infection, the boy developed typical pustules, which disappeared after 14 days. Then Jenner introduced highly infectious material from the pustules of a smallpox patient into the boy’s wound. The boy did not get sick. This is how the idea of ​​vaccination was born and confirmed (from the Latin word vacca - cow). In Jenner's time, vaccination was understood as the introduction of infectious cowpox material into the human body in order to prevent smallpox. The term vaccine was applied to a substance that protected against smallpox. Since 1840, smallpox vaccine began to be obtained by infecting calves. The human smallpox virus was discovered only in 1904. Thus, smallpox is the first infection against which a vaccine was used, i.e., the first vaccine-preventable infection. Advances in vaccine prevention of smallpox have led to its worldwide eradication.

Nowadays, vaccination and vaccine are used as general terms denoting vaccination and vaccination material.

Pasteur, who essentially did not know anything specific about the causes of rabies, except for the indisputable fact of its infectious nature, used the principle of weakening (attenuation) of the pathogen. In order to weaken the pathogenic properties of the rabies pathogen, a rabbit was used, into whose brain the brain tissue of a dog that died of rabies was injected. After the death of the rabbit, its brain tissue was injected into the next rabbit, and so on. About 100 passages were carried out before the pathogen adapted to the rabbit's brain tissue. When injected subcutaneously into the dog's body, it exhibited only moderate pathogenic properties. Pasteur called such a “re-educated” pathogen “fixed”, in contrast to the “wild” one, which is characterized by high pathogenicity. Pasteur later developed a method of creating immunity, consisting of a series of injections with gradually increasing amounts of a fixed pathogen. The dog that completed the full course of injections turned out to be completely resistant to infection. Pasteur came to the conclusion that the process of development of an infectious disease is essentially a struggle between microbes and the body's defenses. “Every disease must have its own pathogen, and we must promote the development of immunity to this disease in the patient’s body,” said Pasteur. Not yet understanding how the body produces immunity, Pasteur was able to use its principles and direct the mechanisms of this process to the benefit of humans. In July 1885, Pasteur had the opportunity to test the properties of a “fixed” rabies pathogen on a child bitten by a rabid dog. The boy was given a series of injections of an increasingly toxic substance, with the last injection containing a completely pathogenic form of the pathogen. The boy remained healthy. The rabies virus was discovered by Remlanger in 1903.

It should be noted that neither the smallpox virus nor the rabies virus were the first viruses discovered to infect animals and humans. The first place rightfully belongs to the foot-and-mouth disease virus, discovered by Leffler and Frosch in 1898. These researchers, using multiple dilutions of the filterable agent, showed its toxicity and made a conclusion about its corpuscular nature.

By the end of the 19th century, it became clear that a number of human diseases, such as rabies, smallpox, influenza, and yellow fever, are infectious, but their causative agents were not detected by bacteriological methods. Thanks to the work of Robert Koch (1843-1910), who pioneered the use of pure bacterial culture techniques, it became possible to distinguish between bacterial and non-bacterial diseases. In 1890, at the X Congress of Hygienists, Koch was forced to declare that “... with the diseases listed, we are not dealing with bacteria, but with organized pathogens that belong to a completely different group of microorganisms.” This statement by Koch indicates that the discovery of viruses was not a random event. Not only the experience of working with pathogens that were incomprehensible in nature, but also an understanding of the essence of what was happening contributed to the formulation of the idea of ​​the existence of an original group of pathogens of infectious diseases of a non-bacterial nature. It remained to experimentally prove its existence.

The first experimental evidence of the existence of a new group of pathogens of infectious diseases was obtained by our compatriot - plant physiologist Dmitry Iosifovich Ivanovsky (1864-1920) while studying mosaic diseases of tobacco. This is not surprising, since infectious diseases of an epidemic nature were often observed in plants. Back in 1883-84. The Dutch botanist and geneticist de Vries observed an epidemic of greening of flowers and suggested the infectious nature of the disease. In 1886, the German scientist Mayer, working in Holland, showed that the sap of plants suffering from mosaic disease, when inoculated, causes the same disease in plants. Mayer was sure that the culprit of the disease was a microorganism, and searched for it without success. In the 19th century, tobacco diseases caused enormous harm to agriculture in our country. In this regard, a group of researchers was sent to Ukraine to study tobacco diseases, which, as a student at St. Petersburg University, included D.I. Ivanovsky. As a result of studying the disease described in 1886 by Mayer as mosaic disease of tobacco, D.I. Ivanovsky and V.V. Polovtsev came to the conclusion that it represents two different diseases. One of them - "grouse" - is caused by a fungus, and the other is of unknown origin. The study of tobacco mosaic disease was continued by Ivanovsky at the Nikitsky Botanical Garden under the leadership of Academician A.S. Famytsina. Using the juice of a diseased tobacco leaf, filtered through a Chamberlant candle, which retains the smallest bacteria, Ivanovsky caused a disease of tobacco leaves. Cultivation of the infected juice on artificial nutrient media did not produce results and Ivanovsky comes to the conclusion that the causative agent of the disease is of an unusual nature - it is filtered through bacterial filters and is not able to grow on artificial nutrient media. Warming the juice at 60-70 °C deprived it of infectivity, which indicated the living nature of the pathogen. Ivanovsky first named the new type of pathogen “filterable bacteria.” Results of the work of D.I. Ivanovsky were used as the basis for his dissertation, presented in 1888, and published in the book “On Two Diseases of Tobacco” in 1892. This year is considered the year of the discovery of viruses.

For a certain period of time, in foreign publications, the discovery of viruses was associated with the name of the Dutch scientist Beijerinck (1851-1931), who also studied tobacco mosaic disease and published his experiments in 1898. Beijerinck placed the filtered juice of an infected plant on the surface of an agar, incubated and obtained bacterial colonies on its surface. After this, the top layer of agar with bacterial colonies was removed, and the inner layer was used to infect a healthy plant. The plant is sick. From this, Beijerinck concluded that the cause of the disease was not bacteria, but some liquid substance that could penetrate inside the agar, and called the pathogen “liquid living contagion.” Due to the fact that Ivanovsky only described his experiments in detail, but did not pay due attention to the nonbacterial nature of the pathogen, a misunderstanding of the situation arose. Ivanovsky’s work became famous only after Beijerinck repeated and expanded his experiments and emphasized that Ivanovsky was the first to prove the non-bacterial nature of the causative agent of the most typical viral disease of tobacco. Beijerinck himself recognized the primacy of Ivanovsky and the current priority of the discovery of viruses by D.I. Ivanovsky is recognized throughout the world.

The word VIRUS means poison. This term was also used by Pasteur to denote an infectious principle. It should be noted that at the beginning of the 19th century, all pathogenic agents were called the word virus. Only after the nature of bacteria, poisons and toxins became clear, the terms “ultravirus” and then simply “virus” began to mean “a new type of filterable pathogen.” The term “virus” took root widely in the 30s of our century.

It is now clear that viruses are characterized by ubiquity, that is, ubiquity of distribution. Viruses infect representatives of all living kingdoms: humans, vertebrates and invertebrates, plants, fungi, bacteria.

The first report related to bacterial viruses was made by Hankin in 1896. In the Chronicle of the Pasteur Institute, he stated that “... the water of some rivers of India has a bactericidal effect...”, which is no doubt related to bacterial viruses. In 1915, Twort in London, while studying the causes of lysis of bacterial colonies, described the principle of transmission of “lysis” to new cultures over a series of generations. His work, as often happens, was virtually unnoticed, and two years later, in 1917, the Canadian de Hérelle rediscovered the phenomenon of bacterial lysis associated with a filtering agent. He called this agent a bacteriophage. De Herelle assumed that there was only one bacteriophage. However, research by Barnett, who worked in Melbourne in 1924-34, showed a wide variety of bacterial viruses in physical and biological properties. The discovery of the diversity of bacteriophages has generated great scientific interest. At the end of the 30s, three researchers - physicist Delbrück, bacteriologists Luria and Hershey, working in the USA, created the so-called “Phage Group”, whose research in the field of genetics of bacteriophages ultimately led to the birth of a new science - molecular biology.

The study of insect viruses has lagged significantly behind the virology of vertebrates and humans. It is now clear that viruses that infect insects can be divided into 3 groups: insect viruses themselves, animal and human viruses for which insects are intermediate hosts, and plant viruses that also infect insects.

The first insect virus to be identified was the silkworm jaundice virus (silkworm polyhedrosis virus, called Bollea stilpotiae). As early as 1907, Provacek showed that a filtered homogenate of diseased larvae was infectious for healthy silkworm larvae, but it was not until 1947 that the German scientist Bergold discovered rod-shaped viral particles.

One of the most fruitful studies in the field of virology is Reed's study of the nature of yellow fever on US Army volunteers in 1900-1901. It has been convincingly demonstrated that yellow fever is caused by a filterable virus that is transmitted by mosquitoes and mosquitoes. It was also found that mosquitoes remained non-infectious for two weeks after absorbing infectious blood. Thus, the external incubation period of the disease (the time required for virus reproduction in an insect) was determined and the basic principles of the epidemiology of arbovirus infections (viral infections transmitted by blood-sucking arthropods) were established.

The ability of plant viruses to reproduce in their vector, an insect, was demonstrated in 1952 by Maramorosh. The researcher, using insect injection techniques, convincingly demonstrated the ability of the aster jaundice virus to multiply in its vector, the six-spotted cicada.

1.2. Stages of development of virology

The history of achievements in virology is directly related to the success of the development of the methodological base of research.

^ End of XIX - beginning of XX century. The main method of identifying viruses during this period was the method of filtration through bacteriological filters (Chamberlan candles), which were used as a means of separating pathogens into bacteria and non-bacteria. Using filterability through bacteriological filters, the following viruses were discovered:

1892 - tobacco mosaic virus;

1898 - foot-and-mouth disease virus;

1899 - rinderpest virus;

1900 - yellow fever virus;

1902 - fowl and sheep pox virus;

1903 - rabies virus and swine fever virus;

1904 - human smallpox virus;

1905 - canine distemper virus and vaccine virus;

1907 - dengue virus;

1908 - smallpox and trachoma virus;

1909 - polio virus;

1911 - Rous sarcoma virus;

1915 - bacteriophages;

1916 - measles virus;

1917 - herpes virus;

1926 - vesicular stomatitis virus.

30s - the main virological method used to isolate viruses and their further identification are laboratory animals (white mice - for influenza viruses, newborn mice - for Coxsackie viruses, chimpanzees - for hepatitis B virus, chickens, pigeons - for oncogenic viruses , gnotobiont piglets - for intestinal viruses, etc.). The first person to systematically use laboratory animals in the study of viruses was Pasteur, who, back in 1881, conducted research on inoculating material from rabies patients into the brain of a rabbit. Another milestone was work on the study of yellow fever, which resulted in the use of newborn mice in virological practice. The culmination of this cycle of work was the isolation by Cycles in 1948 of a group of epidemic myalgia viruses using suckling mice.

1931 - chicken embryos, which are highly sensitive to influenza, smallpox, leukemia, chicken sarcoma and some other viruses, began to be used as an experimental model for isolating viruses. And currently, chicken embryos are widely used to isolate influenza viruses.

1932 - English chemist Alford creates artificial finely porous colloidal membranes - the basis for the ultrafiltration method, with the help of which it became possible to determine the size of viral particles and differentiate viruses on this basis.

1935 - the use of the centrifugation method made it possible to crystallize the tobacco mosaic virus. Currently, centrifugation and ultracentrifugation methods (acceleration at the bottom of the tube exceeds 200,000 g) are widely used for the isolation and purification of viruses.

In 1939, an electron microscope with a resolution of 0.2-0.3 nm was used for the first time to study viruses. The use of ultrathin tissue sections and the method of negative contrasting of aqueous suspensions made it possible to study the interaction of viruses with cells and to study the structure (architecture) of virions. The information obtained using the electron microscope was significantly expanded by X-ray diffraction analysis of crystals and pseudocrystals of viruses. The improvement of electron microscopes culminated in the creation of scanning microscopes that make it possible to obtain three-dimensional images. Using electron microscopy, the architecture of virions and the features of their penetration into the host cell were studied.

During this period, the bulk of viruses were discovered. Examples include the following:

1931 - swine influenza virus and equine western encephalomyelitis virus;

1933 - human influenza virus and eastern equine encephalomyelitis virus;

1934 - mumps virus;

1936 - mouse mammary cancer virus;

1937 - tick-borne encephalitis virus.

40s. In 1940, Hoagland and his colleagues discovered that the vaccinia virus contains DNA but not RNA. It became obvious that viruses differ from bacteria not only in size and inability to grow without cells, but also in that they contain only one type of nucleic acid - DNA or RNA.

1941 - American scientist Hurst discovered the phenomenon of hemagglutination (erythrocyte gluing) using a model of the influenza virus. This discovery formed the basis for the development of methods for detecting and identifying viruses and contributed to the study of virus-cell interactions. The principle of hemagglutination is the basis of a number of methods:

^ HRA - hemagglutination reaction - used to detect and titrate viruses;

HRA - hemagglutination inhibition reaction - is used to identify and titrate viruses.

1942 - Hurst discovers the presence of an enzyme in the influenza virus, which is later identified as neuraminidase.

1949 - discovery of the possibility of culturing animal tissue cells under artificial conditions. In 1952, Enders, Weller and Robbins received the Nobel Prize for developing the cell culture method.

The introduction of the cell culture method into virology was an important event that made it possible to obtain cultured vaccines. Of the currently widely used cultural live and killed vaccines created on the basis of attenuated strains of viruses, vaccines against polio, mumps, measles and rubella should be noted.

The creators of polio vaccines are American virologists Sabin (a trivalent live vaccine based on attenuated strains of polioviruses of three serotypes) and Salk (a killed trivalent vaccine). In our country, Soviet virologists M.P. Chumakov and A.A. Smorodintsev developed a technology for the production of live and killed polio vaccines. In 1988, the World Health Assembly set WHO the goal of eradicating polio worldwide by completely stopping the circulation of wild poliovirus. To date, enormous progress has been made in this direction. The use of global vaccination against polio using “round” vaccination schemes made it possible not only to radically reduce the incidence, but also to create areas free from the circulation of wild poliovirus.

Viruses discovered:

1945 - Crimean hemorrhagic fever virus;

1948 - Coxsackie viruses.

50s. In 1952, Dulbecco developed a method for titrating plaques in a monolayer of chicken embryo cells, which introduced a quantitative aspect to virology. 1956-62 Watson, Caspar (USA) and Klug (Great Britain) develop a general theory of the symmetry of viral particles. The structure of the viral particle has become one of the criteria in the virus classification system.

This period was characterized by significant advances in the field of bacteriophages:

Induction of the prophage of lysogenizing phages has been established (Lvov et al., 1950);

It has been proven that infectivity is inherent in phage DNA, and not in the protein coat (Hershey and Chase, 1952);

The phenomenon of general transduction was discovered (Zinder and Lederberg, 1952).

The infectious tobacco mosaic virus was reconstructed (Frenkel-Conrad, Williams, Singer, 1955-57), and in 1955 the polio virus was obtained in crystalline form (Shaffer, Shwerd, 1955).

Viruses discovered:

1951 - murine leukemia viruses and ECHO;

1953 - adenoviruses;

1954 - rubella virus;

1956 - parainfluenza viruses, cytomegalovirus, respiratory syncytial virus;

1957 - polyoma virus;

1959 - Argentine hemorrhagic fever virus.

The 60s and subsequent years are characterized by the flourishing of molecular biological research methods. Advances in the field of chemistry, physics, molecular biology and genetics formed the basis of the methodological base of scientific research, which began to be used not only at the level of techniques, but also entire technologies, where viruses act not only as an object of research, but also as a tool. Not a single discovery in molecular biology is complete without a viral model.

1967 - Cates and McAuslan demonstrate the presence of a DNA-dependent RNA polymerase in the vaccinia virion. The following year, RNA-dependent RNA polymerase was discovered in reoviruses, and then in paramyxo- and rhabdoviruses. In 1968, Jacobson and Baltimore established that polioviruses have a genomic protein connected to RNA; Baltimore and Boston established that the poliovirus genomic RNA is translated into a polyprotein.

Viruses discovered:

1960 - rhinoviruses;

1963 - Australian antigen (HBsAg).

70s. Baltimore, simultaneously with Temin and Mizutani, reported the discovery of the reverse transcriptase enzyme (revertase) in RNA-containing oncogenic viruses. It is becoming possible to study the genome of RNA viruses.

The study of gene expression in eukaryotic viruses provided fundamental information about the molecular biology of eukaryotes themselves - the existence of the cap structure of mRNA and its role in RNA translation, the presence of a polyadenylate sequence at the 3" end of mRNA, splicing and the role of enhancers in transcription were first identified in the study of animal viruses.

1972 - Berg publishes a report on the creation of a recombinant DNA molecule. A new branch of molecular biology is emerging - genetic engineering. The use of recombinant DNA technology makes it possible to obtain proteins that are important in medicine (insulin, interferon, vaccines). 1975 - Köhler and Milstein produce the first lines of hybrids producing monoclonal antibodies (MAbs). The most specific test systems for diagnosing viral infections are being developed based on mAbs. 1976 - Blumberg receives the Nobel Prize for the discovery of HBsAg. It has been established that hepatitis A and hepatitis B are caused by different viruses.

Viruses discovered:

1970 - hepatitis B virus;

1973 - rotaviruses, hepatitis A virus;

1977 - hepatitis delta virus.

80s. Development of the ideas laid down by domestic scientist L.A. Zilber's idea that the occurrence of tumors may be associated with viruses. The components of viruses responsible for the development of tumors are called oncogenes. Viral oncogenes have proven to be among the best model systems that help study the mechanisms of oncogenetic transformation of mammalian cells.

1985 - Mullis receives the Nobel Prize for the discovery of the polymerase chain reaction (PCR). This is a molecular genetic diagnostic method, which has also made it possible to improve the technology for obtaining recombinant DNA and discover new viruses.

Viruses discovered:

1983 - human immunodeficiency virus;

1989 - hepatitis C virus;

1995 - Hepatitis G virus was discovered using PCR.

1.3. Development of the concept of the nature of viruses

Answers to the questions “What are viruses?” and “What is their nature?” have been the subject of debate for many years since their discovery. In 20-30 years. no one doubted that viruses are living matter. In the 30-40s. It was believed that viruses are microorganisms, since they are able to reproduce, have heredity, variability and adaptability to changing environmental conditions, and, finally, are subject to biological evolution, which is ensured by natural and artificial selection. In the 60s, the first successes of molecular biology determined the decline of the concept of viruses as organisms. In the ontogenetic cycle of the virus, two forms are distinguished - extracellular and intracellular. The term VIRION was introduced to denote the extracellular form of the virus. The differences between its organization and the structure of cells have been established. Facts pointing to a completely different type of reproduction from cells, called disjunctive reproduction, are summarized. Disjunctive reproduction is a temporary and territorial separation of the synthesis of viral components - genetic material and proteins - from the subsequent assembly and formation of virions. It has been shown that the genetic material of viruses is represented by one of two types of nucleic acid (RNA or DNA). It is formulated that the main and absolute criterion for distinguishing viruses from all other forms of life is the absence of their own protein-synthesizing systems.

The accumulated data allowed us to come to the conclusion that viruses are not organisms, even the smallest ones, since any, even minimal organisms such as mycoplasmas, rickettsia and chlamydia have their own protein-synthesizing systems. According to the definition formulated by Academician V.M. Zhdanov, viruses are autonomous genetic structures capable of functioning only in cells with varying degrees of dependence on cellular systems for the synthesis of nucleic acids and complete dependence on cellular protein-synthesizing and energy systems, and undergoing independent evolution.

Thus, viruses are a diverse and numerous group of non-cellular life forms that are not microorganisms, and are united in the kingdom Vira. Viruses are studied within the framework of virology, which is an independent scientific discipline that has its own object and methods of research.

Virology is divided into general and specific, and virological research into fundamental and applied. The subject of fundamental research in virology is the architecture of virions, their composition, features of the interaction of viruses with cells, methods of transferring hereditary information, molecular mechanisms of synthesis of elements and the process of their integration into a whole, molecular mechanisms of variability of viruses and their evolution. Applied research in virology is related to solving problems in medicine, veterinary medicine and phytopathology.

CHAPTER 2

^ STRUCTURAL AND MOLECULAR ORGANIZATION OF VIRUSES

In the ontogenetic cycle of the virus, two stages are distinguished - extracellular and intracellular and, accordingly, two forms of its existence - the virion and the vegetative form. A virion is an entire viral particle, mainly consisting of protein and nucleic acid, often resistant to environmental factors and adapted to transfer genetic information from cell to cell. The vegetative form of the virus exists in a single virus-cell complex and only in their close interaction.

2.1. Virion architecture

The extracellular form of the virus - the virion, designed to preserve and transfer the nucleic acid of the virus, is characterized by its own architecture, biochemical and molecular genetic characteristics. The architecture of virions refers to the ultrafine structural organization of these supramolecular formations, differing in size, shape and structural complexity. A nomenclature of terms has been developed to describe the architecture of viral structures:

A protein subunit is a single polypeptide chain arranged in a certain way.

A structural unit (structural element) is a protein ensemble of a higher order, formed by several chemically related identical or non-identical subunits.

Morphological unit is a group of protrusions (cluster) on the surface of the capsid, visible in an electron microscope. Clusters consisting of five (pentamer) and six (hexamer) protrusions are often observed. This phenomenon is called pentameric-hexamer clustering. If a morphological unit corresponds to a chemically significant formation (preserves its organization under conditions of mild disintegration), then the term capsomere is used.

Capsid is an outer protein sheath or sheath that forms a closed sphere around the genomic nucleic acid.

Core - the inner protein shell directly adjacent to the nucleic acid.

Nucleocapsid is a complex of protein and nucleic acid, which is a packaged form of the genome.

Supercapsid or peplos is the virion envelope formed by a lipid membrane of cellular origin and viral proteins.

The matrix is ​​a protein component located between the supercapsid and the capsid.

Peplomeres and spines are superficial projections of the supercapsid.

As already noted, viruses can pass through the most microscopic pores that trap bacteria, which is why they were called filtering agents. The filterability property of viruses is due to their size, measured in nanometers (nm), which is several orders of magnitude smaller than the size of the smallest microorganisms. The sizes of viral particles, in turn, vary within relatively wide limits. The smallest simple viruses have a diameter of slightly more than 20 nm (parvoviruses, picornaviruses, phage Qβ), medium-sized viruses - 100-150 nm (adenoviruses, coronaviruses). The largest are recognized as vaccinia virus particles, whose dimensions reach 170x450 nm. The length of filamentous plant viruses can be 2000 nm.

Representatives of the Vira kingdom are characterized by a variety of forms. In terms of their structure, viral particles can be simple formations, or they can be quite complex ensembles, including several structural elements. A conditional model of a hypothetical virion, including all possible structural formations, is presented in Figure 1.

There are two types of viral particles (VP), which are fundamentally different from each other:

1) HFs lacking an envelope (non-enveloped or uncovered virions);

2) HF that have an envelope (enveloped or coated virions).

Rice. 1. The structure of a hypothetical virion

2.1.1. The structure of virions lacking an envelope

Three morphological types of virions lacking an envelope have been identified: rod-shaped (thread-like), isometric and club-shaped (Fig. 2). The existence of the first two types of uncovered virions is determined by the way the nucleic acid is folded and its interaction with proteins.

1. Protein subunits bind to the nucleic acid, arranged along it in a periodic manner so that it folds into a spiral and forms a structure called a nucleocapsid. This method of regular, periodic interaction of protein and nucleic acid determines the formation of rod-shaped and filamentous viral particles.

2. Nucleic acid is not associated with a protein shell (possible non-covalent bonds are very mobile). This principle of interaction determines the formation of isometric (spherical) viral particles. The protein shells of viruses that are not associated with nucleic acid are called capsids.

3. Club-shaped virions have a differentiated structural organization and consist of a number of discrete structures. The main structural elements of the virion are the isometric head and the tail. Depending on the virus, the virion structure may also contain a muff, neck, collar, tail shaft, tail sheath, basal lamina, and fibrils. The bacteriophages of the T-even series have the most complex differentiated structural organization, the virion of which consists of all of the listed structural elements.

Virions or their components may have two main types of symmetry (the property of bodies repeating their parts) - helical and icosahedral. If the components of the virion have different symmetries, then they speak of a combined type of HF symmetry. (Scheme 1).

The helical arrangement of macromolecules is described by the following parameters: the number of subunits per turn of the helix (u, the number is not necessarily an integer); the distance between subunits along the helix axis (p); spiral pitch (P); P=pu. A classic example of a virus with a helical symmetry is the tobacco mosaic virus (TMV). The nucleocapsid of this rod-shaped virus measuring 18x300 nm consists of 2130 identical subunits, there are 16 1/3 subunits per turn of the helix, the helix pitch is 2.3 nm.

Icosahedral symmetry is the most effective for constructing closed circuits.