Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES Science 523-526 2006 fdi:010035725 ENG Science 0036-8075 CC:0002393086-0063 5786 10.1016/j.jep.2005.12.022 https://www.documentation.ird.fr/hor/fdi:010035725 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/2025-01/010035725.pdf 313 Horizon (IRD) Human immunodeficiency virus type 1 (HIV-1), the cause of human acquired immunodeficiency syndrome ( AIDS), is a zoonotic infection of staggering proportions and social impact. Yet uncertainty persists regarding its natural reservoir. The virus most closely related to HIV-1 is a simian immunodeficiency virus ( SIV) thus far identified only in captive members of the chimpanzee subspecies Pan troglodytes troglodytes. Here we report the detection of SIVcpz antibodies and nucleic acids in fecal samples from wild-living P.t. troglodytes apes in southern Cameroon, where prevalence rates in some communities reached 29 to 35%. By sequence analysis of endemic SIVcpz strains, we could trace the origins of pandemic ( group M) and nonpandemic ( group N) HIV-1 to distinct, geographically isolated chimpanzee communities. These findings establish P. t. troglodytes as a natural reservoir of HIV-1. 052