Evolutionary relationships of endemic/epidemic and sylvatic dengue viruses

Endemic/epidemic dengue viruses (DEN) that are transmitted among humans by the mosquito vectors Aedes aegypti and Aedes albopictus are hypothesized to have evolved from sylvatic DEN strains that are transmitted among nonhuman primates in West Africa and Malaysia by other Aedes mosquitoes. We tested this hypothesis with phylogenetic studies using envelope protein gene seque nces of both endemic/epidemic and sylvatic strains. The basal position of s ylvatic lineages of DEN-1, -2, and -4 suggested that the endemic/epidemic l ineages of these three DEN serotypes evolved independently from sylvatic pr ogenitors. Time estimates for evolution of the endemic/epidemic forms range d from 100 to 1,500 years ago, and the evolution of endemic/epidemic forms represents relatively recent events in the history of DEN evolution. Analys is of envelope protein amino acid changes predicted to have accompanied end emic/epidemic emergence suggested a role for domain III in adaptation to ne w mosquito and/or human hosts.