Japanese encephalitis virus detected in Culex orientalis, Culex pipiens and Armigeres subalbatus (Diptera: Culicidae) in Korea

Japanese encephalitis virus (JEV) causes significant viral encephalitis and is distributed throughout the Asian countries. The virus is known to be transmitted by Culex tritaeniorhynchus which mainly breeds in rice paddies in Korea.  In this study, we investigated the presence of other mosquito species that can transmit JEV as a second or regional vector. We selected 11 locations as mosquito-collecting locations where JE patients have occurred in five years or summer habitats of migration birds, then subdivided them into 4 collection sites according to mosquito habitats (cowshed, downtown area, forest, and swamp). Mosquitoes were caught using BG-Sentinel trap, CDC black-light trap, Fay-Prince trap, and Gravid trap through 2012(May to October)-2013(May to September). A total of 2,410 pools from 48,389 mosquitoes were prepared according to species, collection date and sites. We performed a SYBR Green 1 based real-time RT-PCR assay to detect JEV from the mosquito pools. A total of 10 JEV-positive pools were detected from Culex orientalis, Culex pipiens, and Armigeres subalbatus. All the detected JEVs were revealed as genotype V by phylogenetic analysis of the envelope gene exception of Armigeres subalbatuswhich was belong to genotype III (Nakayama strain). Our findings confirm that new genotype of JEV was introduced in Korea and suggest that the three mosquito species may play a role in JEV transmission.

Keywords: Japanese encephalitis virus, Korea, phylogentic analysis, real-time RT-PCR