Spatiotemporal dynamics of the HIV-1 CRF06_cpx epidemic in western Africa

Abstract

Objective: To investigate the origin and spatiotemporal dynamics of dissemination of the HIV-1 CRF06-cpx clade in western Africa. Design: Atotal of 180 HIV-1 CRF06-cpx-like pol sequences isolated from 12 different countries from west and west-central Africa over a period of 16 years (1995-2010) were analyzed. Methods: Evolutionary, phylogeographic and demographic parameters were jointly estimated from sequence data using a Bayesian coalescent-based method and combined with molecular epidemiology and spatial accessibility data. Results: The CRF06-cpx most probably emerged in Burkina Faso in 1979 (1970-1985). From Burkina Faso, the virus was first disseminated to Mali and Nigeria during the 1980s and later to other countries from west and west-central Africa. Demographic reconstruction indicates that the CRF06-cpx epidemic grew exponentially during the 1980s, with a median growth rate of 0.82 year^-1 (0.60-1.09 year^-1), and after stabilize. We found a negative correlation between CRF06-cpx prevalence and the geographical distance to Burkina Faso’s capital. Regional accessibility information agrees with the overall geographical range of the CRF06-cpx, but not fully explains the highly heterogeneous distribution pattern of this CRF at regional level. Conclusion: The CRF06-cpx epidemic in western Africa probably emerged at the late 1970s and grew during the 1980s at a rate comparable to the HIV-1 epidemics in the United States and Europe. Burkina Faso seems to be the most important epicenter of dissemination of the HIV-1 CRF06-cpx strain at regional level. The explanation for the current geographical distribution of CRF06-cpx is probably multifactorial.

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