Vector Competence and Viral Interactions of Zika Virus
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Zika virus (ZIKV) (Flaviviridae: Flavivirus) is a mosquito-borne pathogen that has been linked to life-threatening health complications following its emergence in the Americas. As ZIKV continues its northern expansion, it becomes increasingly important to identify the risk for ZIKV transmission in North America through the determination of competent vector species as well as the potential for flavivirus co-infections. The susceptibility to infection and the potential for ZIKV transmission was investigated in mosquito species local to Southern Ontario, Canada. Wild mosquitoes were exposed to a ZIKV-infected blood meal or sugar meal at a final titer of 105 plaque-forming units. Colony Aedes aegypti (Linnaeus) and Aedes albopictus (Skuse) mosquitoes were also fed a ZIKV-infected bloodmeal alongside the wild mosquitoes. ZIKV transmission was not detected among the blood-fed wild mosquitoes, however, low infection rates of 9.7% and 33.3% were observed in Aedes vexans (Meigan) and Coquillettidia perturbans (Walker), respectively. In the sugar-fed wild mosquitoes, a low infection rate (6.1%) and transmission efficiency (1.2%) was observed for Culex pipiens Linnaeus only. Among the colony mosquitoes, Ae. albopictus displayed a higher transmission efficiency. The results indicate that these mosquitoes are not likely to be competent ZIKV vectors. The infection dynamics of ZIKV were further analyzed following simultaneous and sequential exposure to West Nile virus (WNV) (Flaviviridae: Flavivirus) in mammalian and insect cell lines. Cells were co-infected or superinfected with the viruses at a final multiplicity of infection of 0.01. Viral RNA was subsequently extracted and amplified from the supernatant samples. Viral interference was observed in the mammalian cell line but not in the insect cell line. Additionally, the infection order of the viruses had a significant impact on the estimated viral titer. These results may be applicable in areas where the viruses co-circulate and risk of co-infection exists.