Assessment of Local Mosquito Species Incriminates Aedes aegypti as the Potential Vector of Zika Virus in Australia

Abstract

BackgroundWithin the last 10 years Zika virus (ZIKV) has caused unprecedented epidemics of human disease in the nations and territories of the western Pacific and South America, and continues to escalate in both endemic and non-endemic regions. We evaluated the vector competence of Australian mosquitoes for ZIKV to assess their potential role in virus transmission.Methodology/Principal FindingsMosquitoes were exposed to infectious blood meals containing the prototype African ZIKV strain. After 14 days incubation at 28°C and high relative humidity, infection, dissemination and transmission rates were assessed. Infection in Culex annulirostris and Cx. sitiens could not be detected. 8% of Cx. quinquefasciatus were infected, but the virus did not disseminate in this species. Despite having infection rates > 50%, Aedes notoscriptus and Ae. vigilax did not transmit ZIKV. In contrast, Ae. aegypti had infection and transmission rates of 57% and 27%, respectively. In susceptibility trials, the virus dose required to infect 50% (ID50) of Ae. aegypti was106.4 tissue culture infectious dose50 (TCID50)/mL. Additionally, a threshold viral load within the mosquito of at least 105.1 TCID50 equivalents/mL had to be reached before virus transmission occurred.Conclusions/SignificanceWe confirmed Ae. aegypti to be the most likely mosquito vector of ZIKV in Australia, although the restricted distribution of this species will limit the receptive zone to northern Queensland where this species occurs. Importantly, the role in ZIKV transmission of Culex and other Aedes spp. tested will be negligible. Despite being the implicated vector, the relatively high ID50 and need for a high titer disseminated infection in Ae. aegypti suggest that high mosquito population densities will be required to facilitate epidemic ZIKV transmission among the currently immunologically naïve human population in Australia.

De Novo Generation and Characterization of New Zika Virus Isolate Using Sequence Data from a Microcephaly Case

“…aegypti mosquitoes, with the difference in the percentage of mosquitoes infected and the percentage with infectious saliva broadly consistent with the reported rates for a variety of ZIKV isolates in these mosquitoes (23, 25). Previous studies have shown that Australian A.…”

Genetic Characterization of Spondweni and Zika Viruses and Susceptibility of Geographically Distinct Strains of Aedes aegypti, Aedes albopictus and Culex quinquefasciatus (Diptera: Culicidae) to Spondweni Virus

“…quinquefasciatus or Cx . pipiens indicate that many geographically distinct populations are refractory to virus transmission [46,47,51–54]. These results are similar to our findings in both SPONV strains, where infection and dissemination was not detected in Cx .…”

Wolbachia enhances insect‐specific flavivirus infection in Aedes aegypti mosquitoes

“…These viruses belong to diverse families including the Flaviviridae (genus: Flavivirus ) that are positive single‐stranded RNA viruses (Fauquet, Mayo, Maniloff, Desselberger, & Ball, 2005; Karabatsos, 1978). Flaviviruses include Japanese encephalitis virus and Murray Valley encephalitis virus transmitted by Culex species (Erlanger, Weiss, Keiser, Utzinger, & Wiedenmayer, 2009; Kay, Fanning, & Carley, 1984), West Nile virus (WNV) transmitted by a diverse group of mosquitoes including Aedes and Culex species (Mackenzie et al., 2004) and yellow fever virus (YFV), Zika virus (ZIKV), and dengue virus (DENV) that are all transmitted by Aedes aegypti and Aedes albopictus (Black et al., 2002; Hall‐Mendelin et al., 2016; Hayes, 2009). Dengue fever caused by DENV is a severely debilitating disease with 40% of the world's population at risk of infection and an estimated 300 new infections reported yearly (Bhatt et al., 2013).…”