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26 Heterogeneous Distribution and Extremely High Genetic Diversity of HIV-1 Variants in West and West Central Africa
M. Peeters1, C. ToureKane*2, S. Mamadou3, D. Koyalta4, G. Malonga5, E. Mpoudi6, L. Zekeng6, S. Ramata7, C. Mulanga1, F. Liegeois1, C. Montavon1, N. Vidal1, S. Mboup2, and E. Delaporte1
1IRD, Montpellier, France; 2Hosp. Le Dantec, Dakar, Senegal; 3CHU, Niamey, Niger; 4PNLS, Ndjamena, Chad; 5PNLS, Libreville, Gabon; 6PRESICA, Yaounde, Cameroon; and 7CHU, Conakry, Guinee
Background: Determine the distribution of HIV-1 variants and document the genetic diversity of HIV-1 in West and West Central Africa.
Methods: 1,700 HIV-1 samples were genetically characterized in the envelope (V3-V5) by HMA and/or sequencing. The samples were collected between 1997 and 2000 in 9 different countries. On a subset, the genetic subtype was also identified in gag (p24) or in gag and pol (protease and RT).
Results: The predominant subtype is A and CRF02-AG is predominant among env and gag subtype A samples. The relative prevalences of A and CRF02-AG decrease from West to West Central Africa,(>80 to 50%).The intrasubtype diversity is higher in Central Africa, with the identification of sub-subtypes. In West Africa, subtype G is the second most important variant and represents more than 35% of the viruses in Nigeria. CRF06-cpx, a complex A, G, J, K recombinant, represents an important proportion of env G samples in West Africa. In Chad, bordering Nigeria, the second most important variants are subtype D strains, forming a separate subcluster that represents 25% of the circulating strains. In Central Africa more subtypes cocirculate as compared with West Africa, and CRF01-AE, F1, F2, H, J, and K were more prevalent. In Gabon and Cameroon, a proportion of subtype A strains are members of CRF11-cpx, an A, G, J recombinant. CRF06-cpx and CRF11-cpx are restricted to West and West Central Africa, respectively. The frequency of discordant subtypes between gag and env ranges from 10% to up to 30% in Nigeria and DRC. In addition, CRFs that recombined with other subtypes were also observed.
Conclusions: In each country, subtype A or CRF02-AG is predominant but their prevalences can vary significantly. Geographical differences in subtype distributions are seen. The highest genetic diversity is observed in Central Africa: more subtypes cocirculate and intrasubtype distances are higher. The prevalence of recombinant viruses is relative high, and recombinant viruses continue to recombine. Genetic subtype distribution is a dynamic and unpredictable process.
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