Isolation and identification of Japanese encephalitis virus from mosquitoes in Zhejiang province]

To study the situation of arboviruses carried by mosquitoes in Zhejiang province.Mosquitoes were collected from Zhejiang province in 2007. Virus strains were isolated by the inoculation of homogenates of the mosquitoes onto BHK-21 cell line. The isolated strains were identified by serological (IFA) and molecular methods (RT-PCR).Two strains were isolated from mosquitoes causing cytopathogenic effect (CPE) in BHK-21 cells. Results from serological tests showed that both of the two strains were positive for the antibody to Japanese encephalitis virus (JEV). PrM and E gene were then cloned and sequenced. Results from the phylogenetic analysis showed that the isolates belonged to genotype I JEV while through sequence analysis it showed that the homology of nucleotide sequences and amino acid sequences between the two strains were 99.0% and 98.8% respectively. Compared with the JEV vaccine strain SA14-14-2 and two strains, the homology of nucleotide sequences was up to 87.7% and homology of amino acid sequences was up to 96.4%. When comparing with the vaccine strain SA14-14-2, there were 14 common amino acid variations in all the two strains.Two strains of JEV were isolated from mosquitoes collected in Zhejiang province which was the first isolation of genotype I JEV in the province in recent years.