Japanese encephalitis virus (JEV), a mosquito-borne flavivirus, is the main cause of viral encephalitis in Asia. However, with changing climate JEV has the potential to emerge in novel temperate regions. Here, we have assessed the vector competence of the temperate mosquito Culex pipiens f. pipiens to vector JEV genotype III at temperatures representative of those experienced, or predicted in the future during the summer months, in the United Kingdom. Our results show that Cx. pipiens is susceptible to JEV infection at both temperatures. In addition, at 25 °C, JEV disseminated from the midgut and was recovered in saliva samples, indicating the potential for transmission. At a lower temperature, 20 °C, following an incubation period of fourteen days, there were reduced levels of JEV dissemination and virus was not detected in saliva samples. The virus present in the bodies of these mosquitoes was restricted to the posterior midgut as determined by microscopy and viable virus was successfully recovered. Apart from the influence on virus dissemination, mosquito mortality was significantly increased at the higher temperature. Overall, our results suggest that temperature is a critical factor for JEV vector competence and infected-mosquito survival. This may in turn influence the vectorial capacity of Cx. pipiens to vector JEV genotype III in temperate areas.
Bibliographical noteFunding Information:
This study was funded by the Department for Environment, Food and Rural Affairs (DEFRA Project SE4116-Building capacity for vector borne disease). We would like to thank Fiona McCracken and Sue Evans for technical support and Dr. Jonas Schmidt-Chanasi for donating the JEV SA-14 sample used. Arthropods used in this study were provided by the Pirbright Institute under UK under Grant Code BBS/E/I/00007039 awarded to Dr Simon Carpenter as part of funding received from the Biotechnology and Biological Science Research Council (United Kingdom Research and Innovation).
© 2021, The Author(s).