Genetic and temporal dynamics of human immunodeficiency virus type 1 CRF07_BC in Xinjiang, China.

To explore the temporal genetic variation of human immunodeficiency virus type 1 CRF07_BC and reconstruct its epidemic in Xinjiang, China, we studied 216 C2-V4 fragments of env genes sampled from 1996 to 2008. Phylogenetic analysis indicates that the viruses prevailing in Xinjiang form a large monophyletic cluster and may have originated from a common ancestor. The epidemic in Xinjiang was probably established around 1995 (95% confidence interval, 1994-1996). We noted an increased diversity of CRF07_BC over time, with a rapid evolutionary rate we estimated to be 8.3x10(-3) substitutions per site per year in the env gene. After 5-6 years of the epidemic (1997-2002), the transmission rate of CRF07_BC in Xinjiang slowed down, although CRF07_BC infection remained at a high prevalence.