Molecular analysis of dengue 3 viruses detected from dengue outbreak areas in southern Vietnam in 2010

There are four dengue virus serotypes, based on molecular analysis. Each serotype is divided to several different genotypes, such as there are 5 genotypes in dengue virus serotype 3 (DENV-3), in which genotype II was confirmed to be the main etiology cause the big dengue fever/dengue hemorrhagic fever outbreak in Vietnam 1998. Molecular epidemiological study was carried out on DENV-3, which causing dengue fever/dengue hemorrhagic fever in some epidemic areas with high morbidity and mortality from southern Vietnam in 2010. In this study, viral RNA of DENV-3 were extracted directly from dengue fever/dengue hemorrhagic fever patient sera, typing by RT-PCR (reverse transcriptase-polymerase chain reaction) with Lanciotti specific primers, sequencing the entire envelope (E) gene and comparative analysis with DENV-3 strain isolated from the big outbreak of dengue hemorrhagic fever in whole country in 1998. The phylogenetic analysis of DENV-3 from Vietnam as well as previously published strains, the results showed that: Vietnamese DENV-3 belong to genotype II among 5 genotypes classified for worldwide DENV-3 and have been closely related to Thailand isolates. Further researchs need to be carried out in order to confirm the evidence for local genetic evolution and conserved functional structure of E protein of DENV-3.