Extensive variation and strain-specificity in dengue virus susceptibility among African Aedes aegypti populations

Abstract

African populations of the mosquito Aedes aegypti are usually considered less susceptible to infection by human-pathogenic flaviviruses than globally invasive populations found outside Africa. Although this contrast has been well documented for Zika virus (ZIKV), it is unclear to what extent it is true for dengue virus (DENV), the most prevalent flavivirus of humans. Addressing this question is complicated by substantial genetic diversity among DENV strains, most notably in the form of four genetic types (DENV1 to DENV4), that can lead to genetically specific interactions with mosquito populations. Here, we carried out a survey of DENV susceptibility using a panel of seven field-derived Ae. aegypti colonies from across the African range of the species and a colony from Guadeloupe, French West Indies as non-African reference. We found considerable variation in the ability of African Ae. aegypti populations to acquire and replicate a panel of six DENV strains spanning the four DENV types. Although African Ae. aegypti populations were generally less susceptible than the reference non-African population from Guadeloupe, in several instances some African populations were equally or more susceptible than the Guadeloupe population. Moreover, the relative level of susceptibility between African mosquito populations depended on the DENV strain, indicating genetically specific interactions. We conclude that unlike ZIKV susceptibility, there is no clear-cut dichotomy in DENV susceptibility between African and non-African Ae. aegypti. DENV susceptibility of African Ae. aegypti populations is highly heterogeneous and largely governed by the specific pairing of mosquito population and DENV strain.