Phylogenetic evidence suggests that endemic and epi-demic dengue viruses (DENV), transmitted among humansby the anthropophilic mosquitoes Aedes aegypti and Ae.albopictus, emerged when ancestral, sylvatic DENV trans-mitted among nonhuman primates by sylvatic Aedes mos-quitoes adapted to these peridomestic vectors. We testedthis hypothesis by retrospectively examining evidence foradaptation of epidemic and endemic versus sylvatic strainsof DENV-2 to Ae. albopictus and Ae. aegypti. First and sec-ond-generation offspring of mosquitoes from different geo-graphic regions in the Americas and Southeast Asia weretested for their susceptibility to epidemic/endemic and syl-vatic DENV-2 isolates from West Africa, Southeast Asia,and Oceania. Both Aedes species were highly susceptible(up to 100% infected) to endemic/epidemic DENV-2 strainsafter ingesting artificial blood meals but significantly lesssusceptible (as low as 0%) to sylvatic DENV-2 strains. Ourfindings support the hypothesis that adaptation to perido-mestic mosquito vectors mediated dengue emergencefrom sylvatic progenitor viruses
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