EVOLUTIONARY TIME-SCALE AND SELECTION PRESSURE ANALYSIS OF DENGUE SEROTYPE 2 AND 4 CIRCULATING IN EASTERN INDIA WITH PHYLOGENETIC EVIDENCE FOR RECOMBINATION IN DENGUE SEROTYPE 2

Abstract

Dengue is a rapidly emerging and re-emerging mosquito-borne disease and a serious burden on Indian population. Recombination, selection pressure may play a major role in dengue virus (DENV) evolution. The present study describes the evolutionary time-scale of dengue virus serotype 2 and 4 strains along with its recombination study and selection pressure analysis in Kolkata, Eastern India. Sequencing of the CapsidPremembrane-Envelop (C-prM-E) region was performed in DENV2 and 4 strains. Maximum likelihood tree was constructed using MEGA softwere. Bayesian phylogenetic analysis was done using best-t model for each dataset. Recombination and selection pressure on structural genes was determined using Datamonkey online platform and RDP4 software. All DENV2 strains were grouped with cosmopolitan genotype and all DENV4 strains were clustered with Genotype I. Mutations at the B and T cell epitopes were revealed. Nucleotide substitution rate of DENV2: 7.49 ×10−4 substitutions/site/year and DENV4: 6.79 × 10-4 substitutions/site/year. Time to the most recent common ancestor of DENV2 and DENV4 viruses was 185 years and 190 years respectively. STM20039/14 was a recombination product of GWL-18-INDI-01 strain and STM20758A/16 ancestor strains. Selection pressure analysis revealed that purifying negative selection was the major driving force. This is the rst report of recombination in DENV2 Cosmopolitan genotype in India. Also, we are reporting for the rst time about the genetic and evolutionary characteristics of DENV4 strains from Eastern India. This study will be useful for the continuous surveillance of disease burden, viral epidemiology to take proper measures for disease control.