Genetic diversity and evolutionary dynamics of dengue isolates from India.

Dengue virus (DENV) is the mosquito borne virus which causes Dengue Haemorrhagic Fever and Dengue Shock Syndrome. It consists of four distinct serotypes (DENV 1-4). DENV 1, 3 and 4 were classified into five genotypes (GI-GV), where as DENV-2 belongs to American and Cosmopolitan genotypes. Dengue virus is most prevalent in south and Southeast Asia including India. This study was initiated to study the genetic diversity and evolution among the Dengue isolates in India. Pairwise comparison of amino acid sequences among the serotypes has shown that DENV-3 is having less sequence diversity compared to other serotypes having differences in their amino acid numbers. We have analyzed the 50 Indian strains and 19 of those strains have been identified as recombinant strains by using RDP4 package, which are then excluded for future selection. Episodic positive selection of DENV was obtained using MEME with value is ≤ 5. Positive selection on several codons was used to correlate the genetic diversity between serotypes. This study clearly established that diversity of amino acids and inter genotypic recombination of strains are the major cause for antigenicity variation and evolution of DENV within India.