High HIV Type 1 prevalence and wide genetic diversity with dominance of recombinant strains but low level of antiretroviral drug-resistance mutations in untreated patients in northeast Gabon, Central Africa.

The northeast of Gabon, central Africa is characterized by high population density and a high rate of immigration from the surrounding countries. To determine the prevalence, circulating subtypes, and antiretroviral resistance mutations of HIV-1, 810 blood samples were collected from the general population of the two main cities (Oyem and Makokou) of this region. Of these, 61 (7.5%) were found to be positive for HIV-1. Analysis of the env (gp120), pol, and gag (p24) sequences as well as phylogenetic analyses showed at least eight different viral lineages. The most prevalent strains were CRF02 recombinants, followed by subtypes A, D, and C. The remaining strains were found to be F, J, G, and also, for the first time in Gabon, the recombinant form CRF11cpx. Analysis of antiretroviral drug-resistance mutations in protease and reverse transcriptase from this untreated population showed a low level of specific mutations. These mutations were associated with subtype polymorphism rather than with resistance to antiretroviral drugs. The wide diversity and the emergence of recombinant strains are in accordance with the rapid spread of new HIV strains in the population and, thus, the dynamic evolution of the epidemic.