Increasing HIV type 1 polymorphic diversity but no resistance to antiretroviral drugs in untreated patients from Central African Republic: a 2005 study.

As the HIV-1 pandemic becomes increasingly complex and as new countries acceed to antiretroviral drugs, the molecular characterization of HIV-1 strains circulating has important implications for vaccine research and for the efficacy of treatments. To follow the evolution of HIV-1 diversity in African countries, we have carried out a molecular analysis of HIV-1 strains collected from 150 HIV-1-positive pregnant women recruited in Bangui, Central African Republic (CAR). We have sequenced reverse transcriptase (RT) and protease (PROT) genes to (1) characterize the subtypes and CRFs, (2) describe the polymorphism of RT and PROT, particularly at the positions of drug resistance mutations in subtype B, and (3) observe potential drug resistance mutations and evaluate the prevalence of isolates bearing such mutations in this untreated population. The results showed that there is a very high and increasing diversity of HIV-1 strains circulating in CAR; out of 117 samples sequenced, we have observed 45 CRF11_cpx, 22 subtypes A1, 13 subtypes G, 7 subtypes CRF01_AE, 3 subtypes B, 3 subtypes CRF02_AG, 2 of each subtype F2 and CRF09_cpx, and one of each subtype D, J, C, H, CRF06_cpx, CRF13_cpx, and CRF19_cpx; the remaining 13 strains showed discordant genomic results suggesting multiple recombinations leading to mosaic viruses. The polymorphism of RT and PROT was high compared to subtype B, particularly at some positions that have been involved in antiretroviral resistance in subtype B, but we could not observe any major resistance mutation in this sample of untreated patients. The prevalence of drug resistance mutations in this population was therefore clearly under the WHO 5% threshold.