Tracing the Origins of the HIV-1 Epidemic

Previous work suggests that HIV-1 infection in humans began with cross-species transmission of simian immunodeficiency virus — a close relative — from chimpanzees in southern Cameroon. The earliest known infections with group M HIV-1, the cause of the current worldwide pandemic, occurred in Kinshasa in the Democratic Republic of the Congo (DRC). Now, investigators have analyzed HIV-1 sequences from archived samples collected in the DRC and neighboring countries and applied molecular clock techniques — estimates of the viral-mutation rate — to reconstruct how the virus spread.

The analysis suggests that group M HIV-1 emerged in Kinshasa around 1920, which is in line with previous work. From there, the virus spread to other population centers …