Surprisingly high prevalence of subtype C and specific HIV-1 subtype/CRF distribution in men having sex with men in Senegal

Abstract

Background: Recent reports showed the high vulnerability for HIV infection of men who have sex with men (MSM) in Africa. Here, we report the HIV-1 variants that circulate among MSM in Senegal.

Methods: HIV-1 subtype/circulating recombinant form (CRF) was determined in an 1800-base pair fragment of pol for 70 HIV-1-positive samples from MSM. Phylogenetic trees were constructed using the neighbor-joining method with CLUSTALX. Similarity and bootstrap plots were then done for recombination analysis. The maximum likelihood approach was used for the identification of transmission clusters.

Results: Sixty-seven samples (95%) were from Senegalese MSM, 90% unmarried with a median age of 30 years. Fifty-five MSM had regular male partners, but 39 of 70 had also a regular female partner. The overall subtype/CRF distribution was as follows: 28 C (40%), 17 CRF02_AG (24.3%), 13 B (18.6%), 6 G (8.6%), 3 CRF09_cpx (4.3%), and 3 (4.3%) unique recombinants. In addition, 47 sequences (67.15%) were segregated into 15 transmission clusters.

Conclusions: These variants circulate also among the general population or female sex workers, but the proportions are significantly different. Despite the massive stigma, the majority (80%) of MSM recognized having sex with women and could serve as a bridge for intermixing of HIV-1 variants between high-risk men and low-risk women.