HIV type 1 infection in Pygmy hunter gatherers is from contact with Bantu rather than from nonhuman primates.

To investigate the route of zoonotic transmission of HIV-1, we isolated three and seven HIV-1 strains from 449 Pygmy hunter gatherers and 169 neighboring Bantu, respectively, in southern Cameroon. Phylogenetic analysis based on pol-integrase and env-C2V3 sequences revealed that strains from Pygmies were 1 CRF02_ AG/CRF02_AG, 1 subtype G/CRF02_AG (pol/env), and 1 CRF11_cpx/CRF11_cpx, and that those from Bantu were 2 CRF02_ AG/CRF02_AG, 1 CRF02_ AG/CRF01_AE/A, 1 CRF02_ AG/subtype A, 1 G/A, 1 G/CRF02_AG, and 1 unclassified/H. CRF02_ AG and CRF11_cpx have been identified in Cameroon. The results suggest that HIV-1 has been introduced into Pygmies through their neighboring Bantu rather than directly from nonhuman primates.