Chikungunya emergency in China: microevolution and genetic analysis for a local outbreak.

A small-scale local chikungunya outbreak occurred in a Guangdong village of southern China in October 2010. The five chikungunya viruses (CHIKV) isolated from the epidemic and three other imported cases obtained from the same period were sequenced and analyzed for phylogenesis. The results demonstrated that all of the eight sequences were clustered in the Eastern, Central, Southern, and African group. However, the local strains and imported isolates showed different sequence variations. A226V in E1 gene and V264A in E2 gene were detected in all three imported isolates, the unique substitutions S250P in E1 gene and H313Y in E2 genes could be observed in four of the five local strains. These significant variations might be some of the causes for the outbreak. It would be an important event for CHIKV to have mutated adaption to the local mosquitoes in China, Aedes albopictus and Aedes aegypti.