HIV infection is a disease caused by the human immunodeficiency virus (HIV), persistent for a long time in lymphocytes, macrophages, cells of the nervous tissue, resulting in a slowly progressing damage to the immune and nervous systems of the body, manifested by secondary infections, tumors, subacute encephalitis and other pathological changes.
The causative agents of human immunodeficiency viruses 1 and 2, HIV-1, HIV-2, (HIV-1, HIV-2, Human Immunodeficiency Virus, types I, II) belong to the family of retroviruses, a subfamily of slow viruses. Virions are spherical particles with a diameter of 100-140 nm. The viral particle has an external phospholipid shell, which includes glycoproteins (structural proteins) with a certain molecular mass, measured in kilodaltons. In HIV-1, it is gp 160, gp 120, gp 41. The inner envelope of the virus covering the nucleus is also represented by proteins with known molecular weights: p17, p24, p55 (HIV-2 contains gp140, gp105, gp36, p16, p25, p55).
Identification of antibodies to the human immunodeficiency virus using HIV testing is the main method of laboratory diagnosis of HIV infection. The method is based on ELISA (sensitivity - more than 99.5%, specificity - more than 99.8%). Antibodies to HIV appear in 90-95% of infected for 3 months after infection, in 5-9% - after 6 months, in 0.5-1% - in later terms. In the stage of AIDS, the number of antibodies can decrease until it disappears completely. When you receive a positive response (identifying antibodies to HIV) in order to avoid false positive results, the analysis should be repeated one or two times, preferably using a diagnostic series of another series. The result is considered positive, if from two - in both analyzes or from three - in two analyzes antibodies are clearly revealed.