What is antiviral immunity? This is the body's defense mechanism, which ensures the smooth operation of the internal environment and interacts with a pathogenic infectious agent. In modern immunology, this section occupies a predominant part of the theoretical course. Its study is of paramount importance for future immunologists.
What is a virus and how does the immune system react to it
In the nature of infectious microorganisms, viruses are assigned a unique status: all pathogens of various diseases known to modern science have a molecular non-cellular organization. A virus is a kind of intracellular parasite that has a specific mechanism of reproduction and interaction with the cells of the body. Due to the variety of viral infections, scientists were able to determine the type of pathogenesis of diseases caused by them, and the nature of the immunological reaction.
The main task of microbiology antiviralimmunity is the creation of effective drugs that should help the body fight infection and establish an effective defense mechanism in the event of a repeated viral attack. To do this, it is important to determine the degree of resistance of the pathogen to the effects of natural and artificial antiviral complexes that are formed after the infection has been cured.
The antiviral immunity formed by the body can have different intensity and duration. It is also worth clarifying that the immunological reaction in response to infection does not occur in all cases. Immunity to pathogenic agents of certain species is laid down at the genetic level. The main condition for the formation of such mechanisms of antiviral immunity is the absence of specific substrates in cells. Without them, there is no interaction with the infection and its reproduction is blocked. Due to the inability to reproduce the virus in the body, the disease does not develop.
General physiological factors in the formation of immune defenses
Every person has innate antiviral immunity. The main condition for its production is the presence of nonspecific factors that protect cells and molecules from the effects of infection. To provoke the development of the disease, the pathogen must pass several natural barriers in the human body. Each of them is thus a non-specific factor in antiviral immunity.
The first stage is the mucocutaneous tissues. They account for the firstattack by pathogenic microorganisms. Strong antiviral immunity is possessed by intact skin and mucous membranes, which serve not only as a mechanical, but also as a sterilizing obstacle. Otherwise, the virus penetrates further into the body. Phagocytes begin to actively arrive at the infected area, which limit the affected area from other he althy tissues and limit the spread of infection.
An increase in body temperature is a feature of antiviral immunity. With moderate fever (up to 40 ° C), which many actively fight against, immunogenesis is activated, metabolism starts and the production of interferon, a natural antiviral substance, increases. At high body temperature, direct inactivation of the extracellular agent occurs, and its reproduction is suppressed by lowering the pH of the extracellular and intracellular environment. In an acidic environment, the infection dies faster.
Unlike bacteria, most viruses easily pass through the renal system without affecting the functionality of the organs. Literally an hour after infection, viruses appear in the urine, which contributes to the speedy restoration of the relative constancy of the internal environment of the body. That is why, with a viral infection, the patient is advised to drink as much liquid as possible. At the same time, pathogens are excreted not only by the kidneys, but also by the salivary glands and intestines.
Virus in the blood: the role of immunoglobulins, macrophages, hormones
Gamma globulin, whichcontained in the blood serum and is involved in the process of natural neutralization of viruses. A similar function is performed by inhibitors - non-specific antiviral proteins present in the secretion of the epithelium of the mucous membrane of the respiratory and gastrointestinal tract. All these elements of antiviral immunity in microbiology are considered the main factors that suppress the activity of pathogens. Viruses reside outside the sensitive cell, namely in the blood and other fluid tissues.
The protective functions of inhibitors are the same as those of antibodies, which depends on the type of viral infection and its quantitative load on the body. The activity of inhibitors and gamma globulin is influenced by individual and age characteristics. Antiviral immunity is higher with a low content of inhibitors, since they tend to be released and restore their activity. In people of mature age, there are more inhibitors, but the virus neutralized by them subsequently becomes the object of influence of other immunological factors.
Hormonal balance affects resistance to viral infection. So, for example, an increase in the concentration of cortisone in the body reduces protective functions, and in small doses it increases it. Macrophages, cells that phagocytize foreign particles when they enter the bloodstream, deserve special attention among the factors of antiviral immunity. The following macrophages protect the body from viruses:
- blood monocytes;
- bone marrow cells;
- liver cells;
- spleen macrophages;
- lymphocytes.
All these elements are involved in the formation of antibodies, cooperating with T- and B-lymphocytes. The viral agent is adsorbed and absorbed by leukocytes, but its further destruction does not occur and the process stops at the stage of phagocytosis. There is no explicit need to complete this process. Macrophages are not able to digest viruses, and this is the main principle of protection, therefore phagocytosis is assigned a secondary role in immunology. Antiviral immunity in this case depends more on the interference of the organism.
Human leukocyte interferon
If the infection overcomes the above general physiological and humoral factors, it manages to enter the sensitive cell. After that, the process of intracellular development of the virus starts, but in some cases the penetration of infection is not always accompanied by intracellular damage. Morphologically, the cell does not change, no destructive processes occur in it, therefore, in the future, it becomes resistant to strains of this virus.
Antiviral immunity developed as a result of viral interference is considered the strongest. Its material basis is the production of a special substance - interferon. This protein is formed as a response to the penetration of the pathogen into the cell. Interferon has antiviral, antiproliferative and immunomodulatory properties and loses its activity, but does not die at low temperatures. It can be destroyed by exposure to ultraviolet radiation and high temperatures (above 60 ° C).
In the blood, interferon appears 1-2 hours after the penetration of the virus and reaches its maximum concentration after 4-8 hours. Protein occurs as a reaction in response not only to the penetration of viruses, but also bacteria, their metabolic products, being the main element antiviral immunity.
Interferon is present in the blood, urine, cerebrospinal fluid, nasopharyngeal secretions, kidneys, lungs and connective tissue of the body. It is produced by almost all cells, but to a greater extent this protein is produced by the spleen and leukocytes. The principle of action of interferon is to suppress the function of virus reproduction while fully preserving the vital activity of the cell.
The difference between acquired immunity and innate immunity
The immune system of the body's defense against pathogenic microorganisms is of two types - innate and acquired. From the point of view of immunology, the purpose of acquired immunity, which appears in a person during life, is to support innate immunity. Unlike innate immunity, which is present from birth and is activated by the invasion of a foreign microorganism, acquired immunity is formed only after contact with an infection and is activated in the event of a repeated attack.
One way to get acquired immunity to a particular virus is to get vaccinated. Upon initial contact with a foreign agent, several actions are triggered that lead to the launch of lymphocytes and protein synthesis,with increased reactivity against foreign particles. As a result of this process, the body acquires a defense system that confidently resists subsequent attacks.
People who managed to survive the course of deadly epidemics of bubonic plague and smallpox subsequently showed greater resistance to infection than those who had never encountered the disease. The Englishman E. Jenner is considered the discoverer of acquired antiviral immunity.
At the end of the 18th century, this doctor conducted a scientific and practical experiment, for which today he would be deprived of his license and put on trial. Jenner injected the child with a tiny dose of pus taken from a lesion in a woman with cowpox. Thus, he tried to deliberately infect the child, but the experiment was successful: the disease did not occur, despite contact with the pathogen.
History of vaccination
After the experiment on the development of acquired immunity to cowpox in a child, many scientists were puzzled by the creation of a theory of immunization. But about vaccination in the broad masses became known only a hundred years after the Jenner experiment. In addition, the researchers were able to establish that immunity is formed not only to viruses and bacteria, but also to their metabolic products.
It is a proven fact today that immune defenses occur against countless natural and artificial elements, including metals, low molecular weight chemicals, proteins,carbohydrates, nucleotides, and other antigens that trigger an immune response.
Basic remedies for strengthening immunity
To enhance the properties of antiviral immunity necessary to fight various infections, the pharmacological industry is developing drugs that belong to the category of antiviral and immunostimulating. Regardless of the cause of weakened immunity, the choice of such a medication should be trusted by an immunologist. To date, immunomodulating agents are produced in various dosage forms for adults and children.
Classify them as follows:
- stimulants of natural origin;
- drugs based on bacteria;
- biogenic stimulants;
- inducers of human interferon production;
- drugs of animal origin (from bovine thymus);
- adaptogenic immunomodulators;
- synthetic drugs.
At an early age
Drugs that strengthen antiviral immunity and increase the protective properties of the body in children, it is important to choose taking into account the individual characteristics of the child's development. The need to prescribe immunomodulators to children under six months of age, as a rule, does not arise, because from birth, maternal immunity provides reliable protection to the child's body. After six months, the period of transition of immune protection to the production of its own immunoglobulins begins.
For children under three years of age, doctors prescribe drugs from a series of interferons to improve their immune status. At an older age, it is more effective to use herbal remedies or medicines with nucleic acid.
Natural-based immunomodulators
Echinacea is one of the most popular herbs that are used in medicine to improve the tone of the immune system. Preparations containing this component are produced in the form of tablets, tinctures, drops. For children and adults who often suffer from acute respiratory viral infections, doctors prescribe "Immunal" - a drug based on echinacea. The medicine contains the juice of this useful plant and is enriched with minerals. In the form of tablets "Immunal" is prescribed for adults and children from 12 years of age. Drops are prescribed for patients under this age.
In addition to echinacea, other means are used to increase immunity. No less effective antiviral properties:
- Eleutherococcus tincture - the course for adults is 30 days. The medicine not only strengthens the body, but also gives vitality and vigor.
- Ginseng root tincture. It produces a similar therapeutic effect, but unlike Eleutherococcus extract, it has a number of limitations for use.
- Chinese magnolia vine tincture. Increases resistance to stress and strengthens the immune system, making the body resistant to SARS during a period of mass morbidity.
Immune Boosting Bacteria
To increase resistance to infection, special stimulants for immunity are used. Antiviral agents of this type contain an insignificant amount of microbes, particles of their structures. As a result of the entry of substances into the body, a response occurs. Bacterial preparations with immunostimulating properties include:
- "Likopid". The tool is effective for improving the protective functions of the body in secondary immunodeficiency, chronic viral infections. "Likopid" in tablets can be given to children in the absence of contraindications and relapses of infectious pathologies, sluggish inflammation, chronic diseases.
- "Ribomunil". It is used both for the general strengthening of immunity, and for the prevention of ENT diseases. Among the contraindications are intolerance to the components of the drug. "Ribomunil" can be given even to children from six months.
- "Imudon". The drug is available in the form of lozenges that contain bacterial lysates. The drug resists infections in the oral cavity, has an adaptogenic effect and stimulates the immune response. "Imudon" is used in general therapy, otolaryngology and dentistry.
- "IRS-19". It is a nasal spray that is used as an immunomodulatory agent for patients predisposed to upper respiratory tract diseases. Approved for use by children from three months.
Medicines with interferon
Doctors have no doubts about how high the effectiveness of interferons is. Preparations of this group are prescribed at the first symptoms of colds, as well as during an exacerbation of chronic viral infections. Antiviral drugs for immunityallow you to stop the development of symptoms of the disease, increase the overall resistance of the body. However, interferon is not used for preventive purposes.
The cheapest, most common and universal treatment option is the use of Leukocyte Interferon ampoules. The product is available in the form of a dry powder, which must be diluted with water before use. The finished solution can be dripped into the nose or inhaled with it.
Another drug with interferon is Viferon, which is produced in the form of rectal suppositories and ointments. There are no restrictions on the use of this medicine: it is prescribed for adults, children, and pregnant women.
"Anaferon" is a homeopathic remedy that strengthens cellular and humoral immunity. The tablet preparation is produced separately for adults and for children, quickly relieves the symptoms of viral infections. In addition, "Anaferon" is sometimes prescribed to prevent secondary bacterial infection.
Interferon preparations also include interferon inducers containing nucleic acids - Ridostin, Derinat, Poludan. These drugs help to strengthen both innate and adaptive immunity.
Other immunostimulants
Antiviral drugs that increase immunity include biogenic agents such as aloe extract, Kalanchoe in ampoules, FiBS, etc. They act on the whole organism, activating the synthesis of the main active components to respond to the negative impact of an infectiousagent.
In addition to biogenic stimulants, it is also worth noting the immunomodulatory properties of thymus preparations (Tymosin, Vilozen, Splenin). They are made from bovine thymus extract. These drugs are used as intramuscular injections, intranasal drops or sublingual lozenges.
The category of artificial non-specific stimulants includes vitamin-mineral complexes containing coenzymes - low molecular weight compounds of proteins with non-protein type structures.
It is important to understand that any remedy that has immunostimulatory properties is wrong to perceive as a panacea against all viral diseases. Most viruses, once in the human body, remain in it until the end of life. And although it will not be possible to completely get rid of the infection, it is necessary to constantly strengthen antiviral immunity in order to keep the disease under control and prevent the development of complications.
