Large molecular diversity of HIV-1 in Madagascar

AIDS 2006 - XVI International AIDS Conference
Abstract no. CDA0108

Large molecular diversity of HIV-1 in Madagascar

J.-P. Viard¹, C. Rafalimanana², A. Rasamindrakotroka², N. Ramamonjisoa², D. Rajaonatahina², P. Rajaonarivelo², B. Rakotoambinina³, M.-L. Chaix¹, C. Rouzioux¹

Background: Objectives were to determine which HIV-1 subtypes circulate in Madagascar, an island, with a low HIV seroprevalence and where scarce information is available in terms of molecular epidemiology.

Methods: HIV-positive samples were randomly taken from a bank of sera derived from seroprevalence studies performed in different exposure groups (commercial sex workers, clients of STD clinic, pregnant women, voluntary testings) all over the island (Antsiranana, Sainte Marie, Toamasina, Antananarivo, Toalagnaro, Morondava, Mahajanga) in 2005. Real-time PCR was used to amplify viruses in the LTR gene. Reverse transcriptase sequences were compared to reference subtypes and classified in a phylogenetic tree.

Results: Among 22 virus, representing more than half of the positive samples in the prevalence studies, and therefore considered representative, six subtypes were found : A1 (n=8), C (n=6), CRF_02 (n=4), CRF_06 (n=2), CRF_01 (n=1), and B (n=1). Among the A1 and C subtypes, sequence comparison suggested diverse geographic origins. No cluster of a specific subtype could be found in the different areas from which sera were collected, and no subtype was particularly prevalent in any of the exposure groups.

Conclusions: Madagascar harbors a very specific HIV-1 epidemic characterized by a low seroprevalence and a surprisingly important molecular diversity throughout the island, reflecting diverse geographic origins of viruses, and possibly a recent, self-contained, epidemic after introduction of the different subtypes.