THE ACQUIRED IMMUNODEFICIENCY SYNDROME
AIDS was recognized as a novel clinical entity in 1981–82, when the association of severe immunodepression with increased incidence of Pneumocystis carinii pneumonia and Ka-posi’s sarcoma in homosexual men was first recognized as representing possible variations in the spectrum of a new immunodeficiency disease.
The infectious nature of the syndrome was established in 1983 when Drs. Françoise Barre-Sinoussi and J. C. Chermann, at the Pasteur Institute in Paris, isolated a new retro-virus from the lymph node of a patient with disseminated lymphadenopathy and other symptoms that usually precede the development of AIDS. The new virus was initially named LAV (lymphadenopathy-associated virus) and later received the designation of hu-man immunodeficiency virus (HIV).
Two major variants of HIV have been identified. HIV-1, the first to be isolated, exhibits remarkable genetic diversity, and the different variants have been grouped into seven different families or clades, differing by 30 –35% in their primary structures. HIV-2, prevalent in West Africa, was isolated a few years later. HIV-2 is less virulent than HIV-1, rarely causes full-blown AIDS syndrome, and is not spreading as widely and rapidly as HIV-1.