Prevalence, genetic diversity and antiretroviral drugs resistance-associated mutations among untreated HIV-1-infected pregnant women in Gabon, central Africa

Abstract

Background: In Africa, the wide genetic diversity of HIV has resulted in emergence of new strains, rapid spread of this virus in sub-Saharan populations and therefore spread of the HIV epidemic throughout the continent.

Methods: To determine the prevalence of antibodies to HIV among a high-risk population in Gabon, 1098 and 2916 samples were collected from pregnant women in 2005 and 2008, respectively. HIV genotypes were evaluated in 107 HIV-1-positive samples to determine the circulating subtypes of strains and their resistance to antiretroviral drugs (ARVs).

Results: The seroprevalences were 6.3% in 2005 and 6.0% in 2008. The main subtype was recombinant CRF02_AG (46.7%), followed by the subtypes A (19.6%), G (10.3%), F (4.7%), H (1.9%) and D (0.9%) and the complex recombinants CRF06_cpx (1.9%) and CRF11_cpx (1.9%); 12.1% of subtypes could not be characterized. Analysis of ARVs resistance to the protease and reverse transcriptase coding regions showed mutations associated with extensive subtype polymorphism. In the present study, the HIV strains showed reduced susceptibility to ARVs (2.8%), particularly to protease inhibitors (1.9%) and nucleoside reverse transcriptase inhibitors (0.9%).

Conclusions: The evolving genetic diversity of HIV calls for continuous monitoring of its molecular epidemiology in Gabon and in other central African countries.

Figure 1

Map of Gabon, central Africa, with provinces and main cities. In grey, provinces; square, capital; circles, main cities.

Figure 2

Phylogenetic reconstructions for the assignment of HIV-1 subtypes, including the newly sequenced strain, in Gabon, central Africa. (A) Phylogenetic tree of the partial pol gene constructed with a > 1000-bp fragment (n = 95; range, 1004-1073 bp); (B) phylogenetic tree of reverse transcriptase coding region (n = 2; 785 bp); (C) phylogenetic tree of protease coding region (n = 10; range, 467-479 bp). Dataset of sequences was compiled by combining reference sequences representative of groups M (each pure subtype and commonest CRFs), N and O. The CPZ.US.85.CPZUS (AF103818) strain was used as outgroup to root the trees. The neighbor-joining method was used for the partial pol gene, reverse transcriptase and protease coding regions. Confidence levels were estimated for 1000 replicates, and only bootstrapping values higher than 60% were considered significant.