HIV-1 subtype A

HIV can be divided into two major types, HIV type 1 (HIV-1) and HIV type 2 (HIV-2). HIV-1 is related to viruses found in chimpanzees and gorillas living in western Africa, while HIV-2 viruses are related to viruses found in the endangered west African primate sooty mangabey. Subtype A is common in West Africa.

During the period 1996–1997, three highly homogeneous variants of HIV-1 were identified, circulating among injecting drug users (IDUs) in the former Soviet Union republics. One of these belonged to HIV-1 genetic subtype A (IDU-A), another belonged to HIV-1 genetic subtype B (IDU-B) and the third was a recombinant between the first two variants (CRF03_AB). The IDU-A variant was found to be the majority variant (89.7–100%) in 44 of 45 regions of the Russian Federation studied. The IDU-A variant was also found to spreading rapidly through heterosexual transmission in 1999–2003 (30/34, 88%).