Time-scale of minor HIV-1 complex circulating recombinant forms from Central and West Africa

Abstract

Background: Several HIV-1 circulating recombinant forms with a complex mosaic structure (CRFs-cpx) circulate in central and western African regions. Here we reconstruct the evolutionary history of some of these complex CRFs (09-cpx, 11-cpx, 13-cpx and 45-cpx) and further investigate the dissemination dynamic of the CRF11-cpx clade by using a Bayesian coalescent-based method. Results: The analysis of two HIV-1 datasets comprising 181 pol (36 CRF09-cpx, 116 CRF11-cpx, 20 CRF13-cpx and 9 CRF45-cpx) and 125 env (12 CRF09-cpx, 67 CRF11-cpx, 17 CRF13-cpx and 29 CRF45-cpx) sequences pointed to quite consistent onset dates for CRF09-cpx (~1966: 1958-1979), CRF11-cpx (~1957: 1950-1966) and CRF13-cpx (~1965: 1958-1973) clades; while some divergence was found for the estimated date of origin of CRF45-cpx clade [pol = 1970 (1964-1976); env = 1960 (1952-1969)]. Phylogeographic reconstructions indicate that the HIV-1 CRF11-cpx clade most probably emerged in Cameroon and from there it was first disseminated to the Central Africa Republic and Chad in the early 1970s and to other central and western African countries from the early 1980s onwards. Demographic reconstructions suggest that the CRF11-cpx epidemic grew between 1960 and 1990 with a median exponential growth rate of 0.27 year^-1, and stabilized after. Conclusions: These results reveal that HIV-1 CRFs-cpx clades have been circulating in Central Africa for a period comparable to other much more prevalent HIV-1 group M lineages. Cameroon was probably the epicenter of dissemination of the CRF11-cpx clade that seems to have experienced a long epidemic growth phase before stabilization. The epidemic growth of the CRF11-cpx clade was roughly comparable to other HIV-1 group M lineages circulating in Central Africa.

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