Study on the molecular characteristics of dengue vius type 2 isolated from imported patient in Zhejiang province in 2010

Objective:To confirm the aetiology of an imported dengue fever case reported in Zhejiang province in 2010,and to analyze the molecular characteristics and trace of the pathogen.Methods: IgM antibody and nucleic acid of dengue virus were detected,and the virus was isolated from the serum sample collected from the suspected dengue fever case.E and NS1 genes of the isolated strain were sequenced,and their phylogenetic and homology trees were constructed.Results: IgM antibody and RNA of type 2 dengue virus were detected in the serum sample,and type 2 dengue virus named ZJ/02/10 was isolated from the serum sample.The homology of nucleotide(nt) and amino acid(aa) in E gene of ZJ/02/10 and standard type 2 dengue virus NGC strain were 94.7% and 97.6% respectively,but the homology of nt with dengue virus type 1,3,and 4 were 65.3%,64.3% and 65.9%.The ZJ/02/10 strains had the highest similarity with the strain(PHI/St68/00)in both nt and aa of E gene,indicating the closet relation on the phylogenetic tree of E gene.The phylogenetic tree of the NS1 genes was similar to that of E gene.Conclusion: All of the serological,pathological and molecular features demonstrated that the suspected imported case of dengue fever was caused by type 2 dengue virus which was most likely from Philippines.