Vector Competence of Australian Mosquitoes for Chikungunya Virus

Abstract

Chikungunya virus (CHIKV) is a globally emerging arbovirus responsible for unprecedented outbreaks in the western Indian Ocean, the Indian subcontinent and Italy. To assess the receptivity of Australia to CHIKV, we exposed 10 Australian mosquito species to a 2006 strain of CHIKV isolated from a viremic traveler from Mauritius. In susceptibility trials, the infectious dose required to infect 50% of the mosquitoes was 10^0.6 cell culture infectious dose (CCID)₅₀/mosquito for Aedes procax, 10^1.7 CCID₅₀/mosquito for Aedes albopictus, 10^2.1 CCID₅₀/mosquito for Aedes vigilax, and 10^2.6 CCID₅₀/mosquito for Aedes aegypti and Aedes notoscriptus. When exposed to blood meals containing between 10^3.5 and 10^4.1 CCID₅₀/mosquito of CHIKV, infection rates in these five species, plus Coquillettidia linealis, were ≥81%. Subsequent transmission rates ranged between 20% for Ae. notoscriptus and 76% for Ae. vigilax. In contrast, Culex spp. were poor laboratory vectors, with infection and dissemination rates ≤20% and ≤12%, respectively. Although Australia has efficient laboratory vectors, the role a mosquito species plays in potential CHIKV transmission cycles will also depend on its geographical and temporal abundance, longevity, and association with humans.