Tracing the origin and northward dissemination dynamics of HIV-1 subtype C in Brazil.

Previous studies indicate that the HIV-1 subtype C epidemic in southern Brazil was initiated by the introduction of a single founder strain probably originating from east Africa. However, the exact country of origin of such a founder strain as well as the origin of the subtype C viruses detected outside the Brazilian southern region remains unknown. HIV-1 subtype C pol sequences isolated in the southern, southeastern and central-western Brazilian regions (n = 209) were compared with a large number (n ~ 2,000) of subtype C pol sequences of African origin.