Review on HIV Virus

Human immunodeficiency virus (HIV) and its subtypes are retroviruses and the etiologic agents of AIDS. Human retroviruses were unknown until the 1980's. HIV belongs to a large family of ribonucleic acid (RNA) lentiviruses.[21] These viruses are characterized by association with diseases of immunosuppression or central nervous system involvement and with long incubation periods following infection before manifestations of illness become apparent. Retroviruses are broadly classified into three subfamilies, oncoviruses, lentiviruses and spumaviruses, based on electron microscopic morphology of virions and analysis of genome sequences. Oncoviruses are further subclassified into B- C- and D-type particles morphologically (A-type particles are cytoplasmic cores of B- and D-type particles). Not all retroviruses classed as oncoviruses are oncogenic. Some are apparently harmless in their natural hosts; others such as the D type simian retroviruses related to Mason-Pfizer monkey virus induce an immune deficiency which can be as severe as those caused by HIV and SIV. Foamy viruses (spumaviruses) frequently occur in monkeys and great apes, especially in the central nervous system, but the status of human foamy virus has become uncertain. The pathogenesis of HIV infection includes depletion of the total body CD4+ T-cell pool, leading to immunodeficiency. This effect is accompanied by activation of numerous elements of the immune system, leading to a functional immunosuppression (ie, reduced function of remaining CD4+ cells) and a state of inflammation and coagulation that appears to underlie the in- creased risk of non-opportunistic complications observed in patients with HIV infection. Antiretroviral treatment is the best option for longlasting viral suppression and, subsequently, for reduction of morbidity and mortality. However, current drugs do not eradicate HIV-1 infection and lifelong treatment might be needed.