Objective: To study the situation of arboviruses carried by mosquitoes in Zhejiang province.
Methods: 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).
Results: 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.
Conclusion: 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.