ABSTRACT
Objective To investigate the molecular characteristics of Japanese encephalitis virus (JEV) living in vector mosquitoes,from Zhejiang province.Methods A total of 13620 mosquitoes were collected from the monitoring stations located in Cixi city and Xianju county in Zhejiang province,in July and August,2009-2010.Nucleic acid of JEV from the mosquitoes was monitored by using real-time RT-PCR.The virus strains were isolated with BHK-21 cell line,with E genes of the isolated viruses amplified,sequenced and their phylogeny and homology analyzed.Results The positive rates of JEV for those mosquitoes collected in the stations of Cixi and Xianju were 17.0％ (27/159) and 3.4％ ( 1/29 ),respectively.Twenty-two JEV strains were isolated,accounted for 15.4％ among the 143 batches of mosquitoes collected in 2010.All E genes in the 6 sequenced virus isolates contained 1500 nucleotides encoding 500 amino acids,in which no inserts and deletions were identified.The identity rates of nucleotide and amino acid in E gene were 99.2％-99.8％ and 100.0％ among the 6 JEV strains isolated from Zhejiang,99.1％-99.3％ and 99.2％-99.8％ between the Zhejiang strains in 2009-2010 and the Zhejiang strains in 2007-2008,respectively,87.6％-88.0％ and 97.8％ between the 6 Zhejiang strains and the vaccine strain SA 14-14-2 of JEV,respectively.The phylogeny tree of E gene indicated that the JEV isolates in Zhejiang during 2009-2010 was located in the branch of the genotype Ⅰ.Conclusion Mosquitoes collected from Cixi and Xianju areas carried JEV,with the rate of JEV in Cixi higher than in Xianju.All the Zhejiang isolates in 2009-2010 were proven to be the genotype Ⅰ of JEV.