Vector competence of Aedes aegypti, Aedes albopictus, and Culex quinquefasciatus mosquitoes for Mayaro virus

Abstract

Newly emerging or re-emerging arthropod-borne viruses (arboviruses) are important causes of human morbidity and mortality nearly worldwide. Arboviruses such as Dengue (DENV), Zika (ZIKV), Chikungunya (CHIKV) and West Nile virus (WNV) underwent an extensive geographic expansion in the tropical and sub-tropical regions of the world. In the Americas the main vectors, for DENV, ZIKV and CHIKV, are mosquito species adapted to urban environments namely Aedes aegypti and Aedes albopictus, whereas the main vector for WNV is the Culex quinquefasciatus. Given the widespread distribution in the Americas and high permissiveness to arbovirus infection, theses mosquito species might pose an important role in the epidemiology of other arboviruses normally associated to sylvatic vectors. Here, we test this hypothesis by determining the vector competence of Ae. aegypti, Ae. albopictus and Cx. quinquefasciatus to Mayaro (MAYV) virus, a sylvatic arbovirus transmitted mainly by Haemagogus janthinomys that have been causing an increasing number of outbreaks in South America namely in Brazil. Using field mosquitoes from Brazil, female mosquitoes were experimentally infected and their competence for dissemination and transmission for MAYV was evaluated. We found high dissemination rate for MAYV in Ae. aegypti (57.5%) and Ae. albopictus (61.6%), whereas very low rates were obtained for Cx. quinquefasciatus (2.5%). Concordantly, we observed that Ae. aegypti and Ae. albopictus have high transmission ability (69.5% and 71.1% respectively), conversely to Cx. quinquefasciatus that is not able to transmit the MAYV. Notably, we found that very low quantities of virus present in the saliva (undetectable by RT-qPCR) were sufficient and virulent enough to guarantee transmission. Although Ae. aegypti and Ae. albopictus mosquitoes are not the main vectors for MAYV, our studies suggest that these vectors may play a significant role in the transmission of this arbovirus, since both species showed high vector competence in laboratory conditions.

Author summary

The present study showed that Ae. aegypti and Ae. albopictus mosquitoes have high vector competence for MAYV, in laboratory. In contrast, Cx. quinquefasciatus mosquitoes were shown to be refractory to MAYV. Regarding the viral dilution and nanoinjection, higher detection sensitivity was observed after virus nanoinjection into naïve mosquitoes, indicating that only a few viral particles are required to infect mosquitoes, and these particles may not be detected by RT-qPCR before the nanoinjection procedure.