Genetic analysis of HIV-1 strains in rural eastern Cameroon indicates the evolution of second-generation recombinants to circulating recombinant forms.

The HIV-1 genetic diversity in most parts of Cameroon is well described and shown to be very broad. However, little is known about the composition of the HIV-1 epidemic in the rural parts of eastern Cameroon. Therefore, we investigated 25 specimens from this region for their subtypes in gag, pol, and env gene fragments. Along with genetic material of subtypes A1, C, G, CRF01_AE, CRF02_AG, and CRF11_cpx, we also identified a large number (24%, 6/25) of distinct env sequences within the subtype A radiation. CRF02_AG was the predominant genetic form in all genes studied. Half of the specimens studied were considered "pure" based on concordant subtypes in the genes studied, whereas the other half were unique recombinant forms (URFs). Except for 1 URF, all were second-generation recombinants (SGRs), 90% of which contained genetic material of CRF02_AG in at least 1 gene. Notably, we identified individuals from 3 different villages infected with CRF01_AE(gag)CRF02_AG(pol)A(env) strains, which is indicative of the evolution of this URF to a circulating recombinant form (CRF). In addition, we identified a CRF02_AG(pol)C(env) recombinant infecting a man and a woman living in the same village, suggesting horizontal transmission of this recombinant. The current study emphasizes the power of HIV-1 recombination through the generation of SGRs and the evolution of URFs into CRFs. These findings suggest that, in a region where a predominant HIV-1 strain cocirculates among several subtypes, recombination could eventually decrease the proportion of this strain over time, such as CRF02_AG in Cameroon.