Molecular Epidemiology of Japanese Encephalitis Virus in Mosquitoes during 2013- 2014

Abstract

Japanese encephalitis (JE) is a mosquito-borne zoonotic disease caused by the Japanese encephalitis virus (JEV). Japanese encephalitis is widespread in Asia and endemic in Taiwan. Virological surveillance in mosquitoes showed that the genotype III (GIII) strains of JEV were the predominant epidemic strains circulating in Asia before 1990; however, the genotype I (GI) strains have been introduced into China, Japan, Vietnam, South Korea, and Thailand, and cocirculated with or replaced the GIII strains in Asia. Previous studies showed that in Taiwan, all of the JEV strains obtained during 2005- 2007 belonged to GIII of JEV, but the predominant genotype has shifted from GIII to GI during 2008-2012. This study continued to report the genotype distribution, genetic variation, and mosquito species potentially involved in the transmission of JEV during 2013-2014. Overall, 37,637 mosquitoes were collected; 96 pools were tested JEV positive by RT-PCR, including Culex tritaeniorhynchus (94 pools) and Cx. annulus (2 pools). Phylogenetic analysis of envelope gene sequences of JEV isolated from mosquitoes demostrated that GI was the predominant genotype of JEV between 2013 and 2014, whilst only a few GIII strains of JEV were found in Eastern Taiwan. We will continue the monitoring of endemic and newly introduced JEV in Taiwan.