Molecular characterization of Dengue 2 viruses circulated in Hanoi, 2015

Abstract

Dengue is the most common vector-borne viral disease of human. The DENVs are transmitted to humans through the bite of an infective female Aedes mosquitoes. The agent of these diseases, dengue virus, belonging to the genus Flavivirus (group B) in the family Flaviviridae, and existing as four genetically distinct serotypes (DENV1 to DENV4). According to General Department of Preventive Medicine report, Dengue 2 virus (64%) was one of the main causing of Dengue outbreak in Hanoi in 2015. So this study was conducted to describe molecular characterization of Dengue 2 viruses circulated in Hanoi, 2015, providing an overview on the genetic diversity of DENV2 strains. We determined the sequence of E gene (1485 nucleotides) from 22 strains from Hanoi, in 2015, and 105 sequences downloaded from Genbank. The results showed that DENV2
from Vietnam divided into 4 groups of different genotypes. We detected the introduction of the new genotypes, Hanoi DEN2 viruses in this study belonged to Cosmopolitan genotype, imported from India, identifying the estimating time to the most recent common ancestor (tMRCA) ~ 2002. In addition, the new introduction genotype suggest the relatively low herd immunity in Hanoi people, may contribute to the outbreak of dengue in 2015.