Influence of evolutionary events on the Indian subcontinent on the phylogeography of dengue type 3 and 4 viruses.
During 1960-80 dengue disease profile in India was mild despite circulation of all four serotypes of dengue virus (DENV). Increase in disease severity with a concomitant change in the population of DENV-1 and 2 have been reported since then. To determine population dynamics of DENV-3 and 4, the envelope (E) gene sequence was determined for 16 Indian isolates of DENV-3 and 11 of DENV-4 and analyzed together with 97 DENV-3 and 43 DENV-4 global sequences. All Indian DENV-3 isolates belonged to genotype III, lineages C, D, E and F. Lineage F was newly identified and represented non-circulating viruses. Three non-conservative amino acid changes in domain I, II & III were identified during the transition from lineages F/E, associated with mild disease, to A-D, associated with severe disease. For DENV-4, the current viruses clustered in genotype I, lineage C, whilst the isolates from 1960s formed the new genotype V. A 1979 Indian isolate of DENV-4 was found to be an inter-genotypic recombinant of Sri Lankan isolate (1978) of genotype I and Indian isolate (1961) of genotype V. The rates of nucleotide substitution and time to the most recent common ancestor (tMRCA) estimated for DENV-3 (1782-1934) and DENV-4 (1719-1931) were similar to earlier reports. However, the divergence time for genotype III of DENV-3, 1938-1963, was a more accurate estimate with the inclusion of Indian isolates from the 1960s. By phylogeographical analysis it was revealed that DENV-3 GIII viruses emerged from India and evolved through Sri Lanka whilst DENV-4 emerged and dispersed from India. The present study demonstrates the crucial role that India/Sri Lanka have played in the evolution and dispersion of the major genotypes, GIII of DENV-3 and GI of DENV-4 which are more virulent and show higher dissemination potential.
Dengue Group, National Institute of Virology, 20-A, Dr Ambedkar Road, PO Box No 11, Pune 411001, Maharashtra State, India.
J A
JA
Patil
S
S
Cherian
A M
AM
Walimbe
A
A
Bhagat
J
J
Vallentyne
M
M
Kakade
P S
PS
Shah
D
D
Cecilia
D000818:Animals; D003715:Dengue / Q000821:virology*; D003716:Dengue Virus / Q000145:classification* / Q000235:genetics*; D019143:Evolution, Molecular; D005814:Genes, Viral; D005838:Genotype; D006801:Humans; D007194:India; D051379:Mice; D010802:Phylogeny; D058974:Phylogeography; D012641:Selection, Genetic; D013188:Sri Lanka; D014759:Viral Envelope Proteins / Q000235:genetics
D014759:Viral Envelope Proteins