Contrasted transmission efficiency of Zika virus strains by mosquito species Aedes aegypti, Aedes albopictus and Culex quinquefasciatus from Reunion Island.

BACKGROUND

Zika virus (ZIKV) is a mosquito-borne flavivirus that recently emerged in the South Pacific islands and Americas where unprecedented outbreaks were reported. Although Aedes aegypti is considered to be the main vector for ZIKV, other mosquito species have been shown to be potential vectors and differences in vector competence with respect to mosquito strain and ZIKV strain have been demonstrated. In this study we compared the vector competence of three mosquito species Aedes albopictus, Ae. aegypti and Culex quinquefasciatus from Reunion Island for three ZIKV strains.

METHODS

Five mosquito strains (2 strains of Ae. albopictus, 1 of Ae. aegypti and 2 of Cx. quinquefasciatus) were exposed to three ZIKV strains: one African strain (Dak84) and two Asian strains (PaRi_2015 and MAS66). The vector competence parameters (infection rate, dissemination efficiency and transmission efficiency) and viral loads were examined at 14 and 21 days post-infection.

RESULTS

The two Cx. quinquefasciatus strains did not become infected and were therefore unable to either disseminate or transmit any of the three ZIKV strains. Aedes albopictus and Ae. aegypti strains were poorly competent for the two Asian ZIKV strains, while both mosquito species displayed higher infection rates, dissemination and transmission efficiencies for the African ZIKV Dak84 strain. However, this African ZIKV strain was better transmitted by Ae. aegypti as compared to Ae. albopictus.

CONCLUSIONS

Our results show that both Ae. albopictus and Ae. aegypti, from Reunion Island, are more likely to be competent for ZIKV in contrast to Cx. quinquefasciatus which appeared refractory to all tested ZIKV strains. This improves our understanding of the role of mosquito species in the risk of the ZIKV emergence on Reunion Island.