Progress in the Research of Phenotype and Genotype of Japanese Encephalitis Virus in China

Japanese encephalitis virus(JEV)is one of the leading cause of viral encephalitis in Asia.The phenotypic and genotypic characteristics of isolated virus strains are reviewed in this paper.Studies on the biological characteristics of the isolates showed that different isolates existed apparent differences in virus plaque morphology,neuroinvasive pathogenicity in mice,protective antigenicity and hemagglutination property.In China,only genotype Ⅲ JEV strains were isolated before 1977.But since 1977,both genotypeⅠ and Ⅲ JEV strains were isolated and the genotype Ⅰ virus,which was isolated from mosquitoes mostly,has become the dominant strain.Study on the genomic sequence indicated that there was only a few amino acid difference(≤3%) between the two genotype isolates.Comparison between both genotype isolates and widely used live vaccine strain SA14-14-2 revealed that there were only ≤3% amino acid differences,most of which were the SA14-14-2 unique attenuating sites.These results indicate that the SA14-14-2 live vaccine is able to protect people against infection of the both genotype Ⅰ and Ⅲ JEV strains.