What is antiviral immunity? This is the body’s defense mechanism, which ensures uninterrupted 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. His study is of paramount importance to future immunologists.
What is a virus and how does the immune system respond to it
In the nature of infectious microorganisms, viruses are given 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 body cells. Due to the variety of viral infections, scientists were able to determine the type of pathogenesis of the diseases caused by them, and the nature of the immunological reaction.
The main task of the microbiology of antiviral immunity is the creation of effective drugs that should help the body fight infection and establish an effective protective mechanism in the event of a repeated viral attack. For this, it is important to determine the degree of resistance of the pathogen to the effects of natural and artificial antiviral complexes that form after curing an infection.
The antiviral immunity formed by the body can have different tension 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 at the genetic level. The main condition for the formation of such mechanisms of antiviral immunity is the absence of specific substrates in the cells. Without them, there is no interaction with the infection and its reproduction is blocked. Due to the impossibility of reproduction of the virus in the body, the disease does not develop.
General physiological factors in the formation of immune defense
Every person has innate antiviral immunity. The main condition for its production is the presence of non-specific factors that protect cells and molecules from infection. To provoke the development of the disease, the pathogen must go through several natural barriers in the human body. Each of them is the nonspecific factor of antiviral immunity.
The first stage is mucocutaneous tissue. They account for the first attack of pathogenic microorganisms. Intact skin and mucous membranes, which serve not only as a mechanical, but also as a sterilizing obstacle, have strong antiviral immunity. Otherwise, the virus penetrates further into the body. Phagocytes begin to actively arrive at the infected area, which limit the affected area from other healthy tissues and limit the spread of infection.
Features of antiviral immunity include fever. With moderate fever (up to 40 ° C), with which many are actively struggling, immunogenesis is activated, metabolism is triggered, and production of interferon, a natural antiviral substance, is increased. 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 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 recommended to drink as much fluid as possible. In this case, pathogens are secreted not only by the kidneys, but also by the salivary glands and intestines.
Virus in the blood: the role of immunoglobulins, macrophages, hormones
Non-specific factors of antiviral immunity include gamma globulin, which is found in blood serum and is involved in the process of natural neutralization of viruses. Inhibitors perform a similar function - nonspecific antiviral proteins present in the secretion of the epithelium of the respiratory and gastrointestinal mucosa. All these elements of antiviral immunity in microbiology are considered the main factors that suppress the activity of pathogens. Viruses are located outside the sensitive cell, namely in the blood and other liquid 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 release and restore their activity. In mature people, there are more inhibitors, but the virus neutralized by them subsequently becomes the object of influence of other immunological factors.
Resistance to viral infection is affected by the balance of hormonal levels. So, for example, an increase in the concentration of cortisone in the body reduces protective functions, and in small doses it increases. Particular attention among the factors of antiviral immunity deserve macrophages - cells that phagocytose foreign particles when they enter the bloodstream. Macrophages protect the body from viruses:
- blood monocytes;
- bone marrow cells;
- liver cells;
- macrophages of the spleen;
- lymphocytes.
All these elements participate in the processes of antibody formation, cooperating with T- and B-lymphocytes. The viral agent is adsorbed and absorbed by leukocytes, but in the future its destruction does not occur and the process is suspended at the stage of phagocytosis. There is no clear need to complete this process. Macrophages are not able to digest viruses, and this is the main principle of protection, therefore phagocytosis has a secondary role in immunology. Antiviral immunity in this case is more dependent on the interference of the body.
Human leukocyte interferon
If the infection overcomes the above general physiological and humoral factors, it manages to penetrate the sensitive cell. After this, the process of intracellular development of the virus starts, but in some cases, the penetration of the 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 generated as a result of viral interference is considered the strongest. In its material basis lies the production of a special substance - interferon. This protein is formed as a response to the penetration of a pathogen into the cell. Interferon has antiviral, antiproliferative and immunomodulating 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).
Interferon appears in the blood 1-2 hours after the penetration of the virus and reaches a maximum concentration after 4-8 hours. Protein occurs as a reaction in response not only to viruses, but also bacteria and their waste products, being the main element of antiviral immunity.
Interferon is present in the blood, urine, cerebrospinal fluid, nasopharyngeal secretion, in the kidneys, lungs and in the connective tissue of the body. Almost all cells produce it, 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 the multiplication of the virus while fully maintaining the vital functions of the cell.
The difference between acquired immunity and innate
The immune system to protect the body from pathogenic microorganisms is of two types - congenital and acquired. From the point of view of immunology, the purpose of acquired immunity, which appears in humans throughout life, is to support the innate. Unlike innate immunity, which is present from birth and is activated upon invasion of a foreign microorganism, acquired immunity is formed only after contact with the infection and is activated in case of 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 launched that lead to the launch of lymphocytes and the synthesis of proteins with increased reactivity against foreign particles. As a result of this process, the body acquires a protective system that confidently resists subsequent attacks.
People who survived the deadly epidemics of bubonic plague and smallpox subsequently showed greater resistance to infection than those who had never encountered the disease. The discoverer of acquired antiviral immunity is considered to be Englishman E. Jenner.
At the end of the 18th century, this doctor conducted a scientific and practical experiment, for which today he would be deprived of a license and put on trial. Jenner introduced the child an insignificant dose of pus, taken from the lesion in a woman with smallpox. Thus, he tried to intentionally infect the child, but the experiment was successful: the disease did not occur, despite contact with the pathogen.
Vaccination history
After an experiment on developing a child’s acquired immunity to smallpox, many scientists were puzzled by the development of a theory of immunization. But vaccination in the 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 against viruses and bacteria, but also to their metabolic products.
Today, it is a proven fact that immune defense arises against countless natural and artificial elements, including metals, low molecular weight chemicals, proteins, carbohydrates, nucleotides and other antigens in response to which an immune reaction occurs.
The main means to strengthen immunity
To enhance the properties of antiviral immunity necessary to fight various infections, the pharmaceutical industry is developing drugs that are classified as antiviral and immunostimulating. Regardless of the reason for the weakening of immunity, the choice of such a medication should be trusted to the immunologist. To date, immunomodulating agents in various dosage forms for adults and children are produced.
Classify them as follows:
- natural stimulants;
- bacterial preparations;
- biogenic stimulants;
- human interferon production inducers;
- drugs of animal origin (from the thymus gland of cattle);
- adaptogenic immunomodulators;
- synthetic drugs.
In young years
It is important to choose drugs that strengthen antiviral immunity and increase the protective properties of the body in children, taking into account the individual characteristics of the child's development. The need for the appointment of immunomodulators for children under six months of age, as a rule, does not arise, because from birth, maternal immunity provides reliable protection for the child's body. After six months, a period of transition of immune defense to the production of their own immunoglobulins begins.
For children under the age of three, doctors prescribe drugs from a series of interferons to increase their immune status. At an older age, it is more effective to use herbal remedies or medications with nucleic acid.
Natural-based immunomodulators
Echinacea is considered one of the most popular plants that are used in medicine to increase the tone of the immune system. Preparations containing this component are produced in the form of tablets, tinctures, drops. For children and adults, often suffering from acute respiratory viral infections, doctors prescribe "Immunal" - a drug based on echinacea. The medicine contains the juice of this beneficial plant and is enriched with minerals. In the form of tablets, “Immunal” is prescribed for adults and children from 12 years old. For patients younger than this age, drops are prescribed.
In addition to echinacea, other means are also used to increase immunity. Antiviral properties are no less effective:
- Eleutherococcus tincture - the course for adults is 30 days. The medicine not only strengthens the body, but also gives vitality, vitality.
- Ginseng root tincture. It produces a similar therapeutic effect, but unlike eleutherococcus extract, it has a number of limitations for use.
- Tincture of Schisandra chinensis. Increases stress resistance and strengthens the immune system, making the body resistant to acute respiratory viral infections during a period of mass morbidity.
Immunity Enhanced Bacteria
To increase resistance to infection, special stimulants for immunity are used. Antiviral agents of this type contain an insignificant number of microbes, particles of their structures. As a result of the ingestion of substances into the body, a response occurs. Bacterial drugs with immunostimulating properties include:
- "Lycopid." The tool is effective for improving the protective functions of the body with secondary immunodeficiency, chronic viral infections. Likopid tablets can be given to children in the absence of contraindications and relapses of infectious pathologies, sluggish inflammations, and chronic diseases.
- Ribomunil. It is used both for general strengthening of immunity, and for the prevention of ENT diseases. Among the contraindications, intolerance to the components of the drug is distinguished. Ribomunil can be given even to children from six months old.
- "Imudon." The medicine 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." This is a nasal spray, which is used as an immunomodulating agent for patients predisposed to diseases of the upper respiratory tract. It is allowed to use for children from three months.
Medications with interferon
Doctors have no doubts about how high the effectiveness of interferons is. Drugs of this group are prescribed for the first symptoms of colds, as well as during an exacerbation of chronic viral infections. Antiviral drugs for immunity can stop the development of symptoms of the disease, increase the overall resistance of the body. However, for preventive purposes, interferon is not used.
The cheapest, most common and universal treatment option is the use of Interferon Leukocyte 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.
Another drug with interferon is Viferon, which is available in the form of rectal suppositories and ointments. There are no restrictions on the use of this medicine: it is prescribed for both adults and children, and pregnant women.
"Anaferon" is a homeopathic remedy that strengthens cellular and humoral immunity. The tablet preparation is available separately for adults and for children, quickly stopping 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 strengthen both innate and acquired immunity.
Other immunostimulants
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