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Etiology and pathogenesis of a disease or condition (groups of diseases or conditions) The human immunodeficiency virus, first isolated in 1983, belongs to the family of retroviruses, a feature of which is the presence of the reverse transcriptase enzyme, which ensures the reverse direction of the flow of genetic information: from RNA to DNA. The virus contains two strands of RNA; enzymes necessary for its replication (reverse transcriptase, integrase, protease); proteins and glycoproteins (gp41 and gp120) that form the envelope of the virus. Currently, two types of human immunodeficiency virus are known that have some antigenic differences - HIV-1 and HIV-2; the latter is found mainly in West Africa.
The virus enters cells that have a CD4 receptor on their surface (T-helpers, monocytes, macrophages, Langerhans cells, follicular cells of lymph nodes, microglia) by binding its glycoproteins to the CD4 molecule and chemokine receptors. In the cell, HIV RNA is converted into DNA (reverse transcription), which is integrated into DNA in the nucleus of the host cell using the viral integrase enzyme. HIV proteins formed in the cell are exposed to the protease enzyme, which renders them functional.
Thus, the host cell turns into a "machine" for the production of new virions (HIV has a very high replicative activity). Damage to helper T-lymphocytes (CD4) leads to disruption of intercellular interactions within the immune system, its functional failure, gradual exhaustion and, as a result, progressive immunodeficiency. A large number of viral particles circulating in the blood (“viral load” VL) determines the likelihood of a rapid decrease in the number of immune cells. There is a clear relationship between the rate of CD4 decline and the rate of progression of HIV infection in a patient. As a result of impaired function of helper T-lymphocytes, spontaneous activation of B-lymphocytes occurs, which leads to increased production of non-specific immunoglobulins and an increase in the concentration of circulating immune complexes.
The result of disorders in the immune system is a decrease in the body's resistance, a wide range of secondary diseases develop: secondary (opportunistic) infections, oncological, hematological, autoimmune and lymphoproliferative diseases. A characteristic manifestation of HIV infection is chronic inflammation with damage to all organs and systems: autoimmune reactions, immune complex diseases and metabolic disorders lead to damage to the vascular endothelium and connective tissue with the development of cardiovascular, neurological, endocrine and osteoarticular pathologies.