Genetic and Biological Properties of HIV Type 1 Isolates Prevalent in Villagers of the Cameroon Equatorial Rain Forests and Grass Fields: Further Evidence of Broad HIV Type 1 Genetic Diversity

To understand the evolution of HIV-1, the genetic and biological characteristics of viruses that infect persons living in regions in which the virus has been evolving for several decades must be studied. Thus, we investigated the genetic subtypes, coreceptor usage, and syncytium-inducing ability of viruses in 47 HIV-1-infected blood samples from individuals living in rural villages in the equatorial rain forest and grass field regions in Cameroon. Heteroduplex mobility analysis (HMA) of gag (part of p24 and p7) and env (C2V5) or sequence and phylogenetic analysis of gag (part of p24 and p7), pol (protease), and env (C2V5), revealed a broad HIV1 group M genetic diversity. Subtype analysis revealed genetic evidence of seven subtypes (A, C, D, F, G, H, and J) and three circulating recombinant forms (CRFs) (CRF01_AE, CRF02_AG, and CRF11_cpx). Only 15 (32%) of the 47 samples analyzed revealed a concordant subtype in all three genes (gag, pol, and env), while discordant subtypes and CRFs were identified for the remaining 32 (68%) samples. Two patterns of HIV-1 diversity could be discerned in two provinces. While more concordant subtypes in gag, pol, and env genes were identified in villages of the South province (10 of 13, 77%), the HIV-1 diversity in the West province was characterized by intersubtype recombinants (63%). Five new intersubtype recombinants were identified including A^gag J^pol G^env, G^gag U^pol A^env, AG^gag J^pol A^env, A^gag AG^pol H^env, and C^gag AG^pol AG^env. All of the 40 viruses tested used the R5 coreceptor, of which four also used the X4 coreceptor. Four viruses were able to induce syncytia in MT-2 cells, however, syncytium induction did not correlate with coreceptor usage. This study further reveals the complexity of HIV-1 infection in rural Cameroon and points to the future of the global epidemic, which may be characterized by more genetically diverse viruses.