A Wolbachia wMel Transinfection in Aedes albopictus Is Not Detrimental to Host Fitness and Inhibits Chikungunya Virus

Abstract

Wolbachia inherited intracellular bacteria can manipulate the reproduction of their insect hosts through cytoplasmic incompatibility (CI), and certain strains have also been shown to inhibit the replication or dissemination of viruses. Wolbachia strains also vary in their relative fitness effects on their hosts and this is a particularly important consideration with respect to the potential of newly created transinfections for use in disease control. In Aedes albopictus mosquitoes transinfected with the wMel strain from Drosophila melanogaster, which we previously reported to be unable to transmit dengue in lab challenges, no significant detrimental effects were observed on egg hatch rate, fecundity, adult longevity or male mating competitiveness. All these parameters influence the population dynamics of Wolbachia, and the data presented are favourable with respect to the aim of taking wMel to high population frequency. Challenge with the chikungunya (CHIKV) virus, for which Ae. albopictus is an important vector, was conducted and the presence of wMel abolished CHIKV dissemination to the saliva. Taken together, these data suggest that introducing wMel into natural Ae. albopictus populations using bidirectional CI could be an efficient strategy for preventing or reducing the transmission of arboviruses by this species. The tiger mosquito Aedes albopictus is an invasive disease vector whose range has expanded throughout the tropics, and some temperate regions, in recent decades from its native South East Asia. It is an important vector of human viruses including dengue and chikungunya; in recent years a mutation has been detected in chikungunya virus that specifically increases transmission efficiency by Ae. albopictus, causing concern that epidemics of this disease will become more widespread and severe. Here we show that when transinfected with a strain of the symbiont Wolbachia called wMel, originating in fruitflies, the ability of the mosquito to transmit the mutated chikungunya virus was abolished in lab experiments. Furthermore, the wMel strain was shown to produce no detectable fitness costs in this new host, examining numbers of eggs produced, egg hatch, lifespan, and male mating competitiveness compared to wildtypes. This is encouraging with respect to developing the system for use in the control of dengue and chikungunya viruses.