Currently, the problem of HIV affects many people. Society is trying to protect itself from becoming infected with the virus. It is known that the result of the development of a disease caused by HIV is a fatal outcome. From childhood, people are taught simple protection rules that help reduce the chance of getting the virus. In the article, we will find out the detailed structure of the virus (HIV), how it attacks and interacts with the cells of the human body.
What is human immunodeficiency virus
HIV (human immunodeficiency virus) provokes a slow development of infection in a healthy body. When the virus enters the bloodstream, it begins to gradually destroy healthy cells of the immune system. During the life of the virus, its amount in the body increases, and the number of lymphocytes is steadily decreasing. From the onset of infection to death, doctors distinguish 5 stages that the virus-infected organism undergoes. The last stage is AIDS (acquired immunodeficiency syndrome).
It is possible to become infected by direct contact with an infected person. This usually occurs when interacting with mucous secretions or by damaging the skin. The following biological fluids are dangerous:
- blood;
- seminal fluid;
- vaginal discharge;
- breast milk of mother.
When contact with infected material has occurred, the virus enters the body and hides for a while (incubation period). After which it begins to act actively, and the first symptoms of infection appear.
This virus belongs to the family of retroviral, a subclass of lentiviruses. The name of the subclass comes from the Latin word lente - “slow”, which is directly related to the behavior of the pathogen. Once in the human body, it develops slowly, but the features and structure of the virus (HIV) are such that in every body it behaves differently and multiplies at different speeds.
Virus under the microscope
Upon closer inspection, the pathogen is similar to a sphere, along the edges of which there are thorns. The size of the virus reaches 150 nanometers, which is more than many other infectious agents. The outer layer of the sphere is responsible for the contact of the virus with the cells of the body. It consists of proteins and vertical growths.
In appearance, the spikes resemble mushrooms - they have a thin leg with a hat. Thanks to growths, the virus can contact with other cells. Glycoproteins (GP120) are located on the top of the cap, and the stem consists of transmembrane glycoproteins (GP41).
In the main (inner) part of the virus, there is a genome of 2 molecules consisting of 9 genes. It is in them that the hereditary memory of the virus has accumulated over the time of its existence. It contains information on the structure, pattern of infection and the principle of reproduction of the virus. The gene itself is encapsulated in matrix and capsid proteins (P17 and P24). You can look at the photo of the structure of the virus (HIV) throughout the article.
Scientists have identified 4 immunodeficiency viruses:
- HIV-1 is considered the most common species. The main distribution area is North and South America, Eurasia and Asia. This species is considered the main cause of HIV infection.
- HIV-2 is less common, but is a direct relative of HIV-1. Causes acquired human immunodeficiency syndrome. Distribution began in western Africa.
- HIV-3, HIV-4 is the rarest form of the virus.
Virus structure
Infection of the body and the destruction of immune cells are the main functions of the virus. The structure of HIV has the following:
- Nucleocapsid is the core of the virus. The composition includes 2 molecules and enzymes revertase, protease and integrase. All these components are enclosed in a package of capsid proteins (P7, P9, P24), and 2,000 P17 molecules (matrix protein) are located on top. They are located between the outer shell and the capsid.
- The membrane is the outer shell of the virus. It consists of a layer of phospholipids, membrane cells and glycoproteins (they help to choose the right molecules of the human body for the subsequent attack).
Virus proteins
The composition of the virus (HIV) includes the following proteins:
- Supercapsid. The structure of the virus (HIV) necessarily includes these components in its composition, since they help to perform anchor (with the help of supercapsid the virus attaches to the cell) and address (search for targets) functions. They belong to complex glycoproteins.
- Structural proteins help form the outer shell of the virus and its capsid.
- Non-structural proteins are responsible for POL genes. Thanks to this type of protein, the reproductive functions of the virus occur.
- Capsid proteins form a niche for nucleic acid, and also help create enzymes and are present in the genome of the virus.
What cells are infected with HIV?
When the virus enters the bloodstream of a person, it attacks cells containing the CD4 gene (monocytes, macrophages, T-lymphocytes and all related cells). Due to the structure of the human immunodeficiency virus (namely, part of the glycoprotein), it attacks cells with this gene. Locations that the virus infects:
- all lymphoid tissues;
- microglia cells (nervous system);
- intestinal epithelial cells.
The process of interaction between HIV and target cells
The main defenders of the body are T-lymphocytes, they are sent to fight the virus. Lymphocytes contain the CD4 gene, which the HIV virus responds to. He joins the T-lymphocyte through the specified gene. As already mentioned, this process occurs due to glycoproteins located on the spikes of the virus (GP120). After that, the pathogen begins to actively penetrate into the lymphocyte - transmembrane proteins (GP41) help to do this.
The virus, which is inside the T-lymphocyte, enters a favorable environment for reproduction. Some time after active replication, the infectious agent becomes closely inside the membrane, and it bursts. This process is constantly repeated and an increasing number of cells of the immune system die.
When taking blood for analysis, in a healthy patient, CD4 is determined normally from 4 to 12 units. And in a person with HIV infection, their number decreases and ranges from 0 to 3 units.
Due to its structure, the HIV virus, falling into a healthy body, freezes for a certain time. He needs a period for adaptation - basically this period lasts about 7 days. After that, a stronger virus begins to act.
Due to the location of the virus inside the cells, it successfully hides from any medications, and the immune system stops responding correctly.
HIV development stages
The special structure of the HIV virus suggests its gradual development in the body. An increase in its number allows for active attacks on the body. There are several stages of HIV development (for each person they proceed differently, depending on the state of the body at the time of infection):
- The incubation period takes from 2 weeks to six months. Duration depends on the number of viruses that enter the body. If a small number hits, then they will need more time to increase the number. The stage proceeds without symptoms, but the person is already considered a carrier of the virus.
- Acute infection. At the second stage, the number of viruses grows, and the number of T-lymphocytes begins to decrease. The first symptoms of the disease appear: the lymph nodes increase, the temperature rises or a rash appears.
- The latent stage is the longest stage in time; it takes about 6–7 years. There are practically no external manifestations of the disease. The process takes place inside the body, viruses are actively involved in the destruction of T-lymphocytes. If you take auxiliary, supportive drugs, the lull period can be extended to 10 years.
- Stage of secondary diseases. This period begins after the destruction of most of the immune system. Any catarrhal disease occurs with serious complications and the appearance of additional ailments.
- AIDS. At the last stage, the entire immune system is destroyed in the patient’s body. Such patients are in the hospital under round-the-clock supervision. The body, which is unable to fight, begins to completely exhaust itself, the organs cease to work correctly, tears and purulent wounds appear on the skin. Thanks to treatment, you can only alleviate the condition of the patient and delay the inevitable outcome.
In order not to become infected with the virus, it is necessary to observe the rules of personal safety and remember that the pathogen can enter the human body through contact with biological fluids.
Knowledge of the structure of the virus (HIV) helps scientists fight this disease and restrain its development. Describe to your doctor the symptoms that arose after a possible infection - this will help you choose the right treatment.