Variable effects ofWolbachiaon alphavirus infection inAedes aegypti

2.AbstractWolbachia pipientis(=Wolbachia) has promise as a tool to suppress virus transmission byAedes aegyptimosquitoes. However,Wolbachiacan have variable effects on mosquito-borne viruses. This variation remains poorly characterized, yet the multimodal effects ofWolbachiaon diverse pathogens could have important implications for public health. Here, we examine the effects of somatic infection with two strains ofWolbachia(wAlbB andwMel) on the alphaviruses Sindbis virus (SINV), O’nyong-nyong virus (ONNV), and Mayaro virus (MAYV) inAe. aegypti. We found variable effects ofWolbachiaincluding enhancement and suppression of viral infections, with some effects depending onWolbachiastrain. BothwAlbB- andwMel-infected mosquitoes showed enhancement of SINV infection rates one week post-infection, withwAlbB-infected mosquitoes also having higher viral titers than controls. Infection rates with ONNV were low across all treatments and no significant effects ofWolbachiawere observed. The effects ofWolbachiaon MAYV infections were strikingly strain-specific;wMel strongly blocked MAYV infections and suppressed viral titers, whilewAlbB did not influence MAYV infection. The variable effects ofWolbachiaon vector competence underscore the importance of further research into how this bacterium impacts the virome of wild mosquitoes including the emergent human pathogens they transmit.Impact statementIn recent years, wild populations ofAedes aegyptimosquitoes have been deliberately infected withWolbachia—a bacterium that helps to curb the spread of some pathogens including dengue virus. But how doesWolbachiaaffect the ability of mosquitoes to become infected with and spread the many different viruses they encounter in nature? Here, we characterize the effects ofWolbachiaon three alphaviruses that cause illness in humans— Sindbis virus, O’nyong-nyong virus, and Mayaro virus. We findWolbachiahas variable effects on these pathogens, including significant enhancement of Sindbis virus infections. Our research has important implications for the design of vector control strategies, and suggests further research is needed to understand howWolbachiashapes the replication and transmission of diverse viruses.3.Data SummaryAll data in the study are available in the Figures and supplementary material.