title: Evolution, dispersal and replacement of American genotype dengue type 2 viruses in India (1956-2005): selection pressure and molecular clock analyses.
abstract: This study reports the phylogeny, selection pressure, genotype replacement and molecular clock analyses of many previously unstudied dengue type 2 virus (DENV-2) strains, isolated in India over a time span of almost 50 years (1956-2005). Analysis of complete envelope (E) gene sequences of 37 strains of DENV-2 from India, together with globally representative strains, revealed that the American genotype, which circulated predominantly in India during the pre-1971 period, was then replaced by the Cosmopolitan genotype. Two previously unreported amino acid residues, one in the American (402I) and one in the Cosmopolitan (126K) genotypes, known to be involved functionally in the cellular tropism of the virus, were shown to be under positive selection pressure. The rate of nucleotide substitution estimated for DENV-2 was 6.5x10(-4) substitutions per site year(-1), which is comparable with earlier estimates. The time to the most recent common ancestor of the pre-1971 Indian strains and the American genotype was estimated to be between 73 and 100 years (1905-1932), which correlates with the historical record of traffic between India and South America and suggests transportation of the virus from the Americas. Post-1971 Indian isolates formed a separate subclade within the Cosmopolitan genotype. The estimated time to the most recent common ancestor of the Indian Cosmopolitan strains was about 47 years, with further estimates indicating the migration of DENV-2 from India to countries across the Indian ocean between 1955 and 1966. Overall, the present study increases our understanding of the events leading to the establishment and dispersal of the two genotypes in India.
authors.affiliation: National Institute of Virology, Pashan, Pune - 411021, Maharashtra, India.
authors.forename: Sandeep R P
authors.initials: SR
authors.lastname: Kumar
authors.forename: Jayashri A
authors.initials: JA
authors.lastname: Patil
authors.forename: D
authors.initials: D
authors.lastname: Cecilia
authors.forename: Sarah S
authors.initials: SS
authors.lastname: Cherian
authors.forename: Pradip V
authors.initials: PV
authors.lastname: Barde
authors.forename: Atul M
authors.initials: AM
authors.lastname: Walimbe
authors.forename: Pragya D
authors.initials: PD
authors.lastname: Yadav
authors.forename: Prasanna N
authors.initials: PN
authors.lastname: Yergolkar
authors.forename: Paresh S
authors.initials: PS
authors.lastname: Shah
authors.forename: Vasant S
authors.initials: VS
authors.lastname: Padbidri
authors.forename: Akhilesh C
authors.initials: AC
authors.lastname: Mishra
authors.forename: Devendra T
authors.initials: DT
authors.lastname: Mourya
mesh_terms: D000818:Animals; D016000:Cluster Analysis; D003715:Dengue / Q000453:epidemiology* / Q000821:virology*; D003716:Dengue Virus / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D019143:Evolution, Molecular; D005838:Genotype; D006801:Humans; D007194:India / Q000453:epidemiology; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D010802:Phylogeny; D012367:RNA, Viral / Q000235:genetics; D012641:Selection, Genetic; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D014759:Viral Envelope Proteins / Q000235:genetics
chemical_list: D012367:RNA, Viral; D014759:Viral Envelope Proteins