HIV-1 genetic diversity and primary drug resistance mutations before large-scale access to antiretroviral therapy, Republic of Congo

Abstract

Background: In this work, we investigated the genetic diversity of HIV-1 and the presence of mutations conferring antiretroviral drug resistance in 50 drug-naïve infected persons in the Republic of Congo (RoC). Samples were obtained before large-scale access to HAART in 2002 and 2004.

Methods: To assess the HIV-1 genetic recombination, the sequencing of the pol gene encoding a protease and partial reverse transcriptase was performed and analyzed with updated references, including newly characterized CRFs. The assessment of drug resistance was conducted according to the WHO protocol.

Results: Among the 50 samples analyzed for the pol gene, 50% were classified as intersubtype recombinants, charring complex structures inside the pol fragment. Five samples could not be classified (noted U). The most prevalent subtypes were G with 10 isolates and D with 11 isolates. One isolate of A, J, H, CRF05, CRF18 and CRF37 were also found. Two samples (4%) harboring the mutations M230L and Y181C associated with the TAMs M41L and T215Y, respectively, were found.

Conclusion: This first study in the RoC, based on WHO classification, shows that the threshold of transmitted drug resistance before large-scale access to antiretroviral therapy is 4%.

Keywords: Congo; Drugs resistances; HIV; Recombination; Subtypes.

Fig. 1

Phylogenetic relationships of 1800 unambiguously aligned nucleotide sequences representing the partial pol gene. Sequences were aligned with HIV-1 subtype/CRF reference sequences, and the phylogenetic trees were constructed with the neighbor-joining method implemented with the Clustal Program. Reference strains are in black and samples in grey. The recombined strains are indicated with an asterisk

Fig. 2

Schematic representation of the mosaic pol sequences. The bootstrap values supporting the subtype assignments in the subregion trees were all above 80%