Molecular evolution of human immunodeficiency virus type 1 subtype A in Senegal: 1988-1997

Objective: Few studies have been able to track the genetic diversity of HIV -1 viruses in human populations over time. We analyzed the molecular evolut ion of subtype A over a 10-year period, in a cohort of female sex workers w ith a known rime of infection. Study Design/Methods: We amplified and sequenced the C2-V3 region of the su rface envelope glycoprotein from 73 HIV-1-infected women, infected between 1987-1997. Results: Fifty-one patients were infected by subtype A viruses. The viruses demonstrated significant diversification (P < 0.001) with mean genetic dis tance increasing from 8.6%in 1989 to 15.9% in 1997. The slope of the fitted curve suggested a rate of diversification of 0.7% per year. The majority o f subtype A Viruses clustered with HIV-1 subtype A/G recombinant form (IbNG ). Conclusion: The genetic diversity of HIV-1 subtype A infections doubled ove r the first 10 years of this high risk population's epidemic, suggesting th at implementation of vaccines early in the epidemic may have a higher likel ihood of success based on levels of genetic diversity. The A/G recombinant form (IbNG) has taken epidemic proportions in West Africa. This is of parti cular importance in understanding the epidemiology of HIV-I subtypes in Afr ica and to further dissect the potential phenotypic and biological characte ristics of these viruses.