Oral susceptibility of aedine and culicine mosquitoes (Diptera: Culicidae) to Batai Orthobunyavirus

Background: A number of zoonotic mosquito-borne viruses have emerged in Europe in recent decades. Batai virus (BATV), a member of the genus Orthobunyavirus, is one example of a relatively newly emerged mosquito-borne virus, having been detected in mosquitoes and livestock. We conducted vector competency studies on three mosquito species at a low temperature to assess whether Aedes and Culex mosquito species are susceptible to infection with BATV. Methods: Colonised lines of Aedes aegypti and Culex pipiens and a wild-caught species, Aedes detritus, were orally inoculated with BATV strain 53.2, originally isolated from mosquitoes trapped in Germany in 2009. Groups of bloodfed female mosquitoes were maintained at 20 degrees C for 7 or 14 days. Individual mosquitoes were screened for the presence of BATV in body, leg and saliva samples for evidence of infection, dissemination and transmission, respectively. BATV RNA was detected by reverse transcription-PCR, and positive results confirmed by virus isolation in Vero cells. Results: Aedes detritus was highly susceptible to BATV, with an infection prevalence of >= 80% at both measurement time points. Disseminated infections were recorded in 30.7-41.6% of Ae. detritus, and evidence of virus transmission with BATV in saliva samples (n = 1, days post-infection:14) was observed. Relatively lower rates of infection for Ae. aegypti and Cx. pipiens were observed, with no evidence of virus dissemination or transmission at either time point. Conclusions: This study shows that Ae. detritus may be a competent vector for BATV at 20 degrees C, whereas Ae. aegypti and Cx. pipiens were not competent. Critically, the extrinsic incubation period appears to be <= 7 days for Ae. detritus, which may increase the onward transmissibility potential of BATV in these populations.

Automated summary

This study demonstrates that Aedes detritus may be a competent vector for BATV at 20 degrees C, while Aedes aegypti and Culex pipiens were not competent. The extrinsic incubation period for Aedes detritus appears to be less than or equal to 7 days, potentially increasing the transmission potential of BATV in these populations.