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Abstracts of the papers presented at the International Conference of Indian Virological Society on “Emerging and Re-emerging viral Diseases of the Tropics and Subtropics” at Indian Agricultural Research Institute, New Delhi, India, December 11–14, 2007.
Chikungunya (CHIK) virus re-emerged after a long gap in several countries. India experienced an explosive epidemic after a long gap of 32 years with a shift of the virus from Asian to African genotypes. Kerala was the last state to be affected during 2006 and the resurgence continued in 2007 affecting the entire state. To monitor the changes at molecular level, sequence analysis of the viruses isolated in 2006 (IND-06-Kerala) and 2007 (IND-07-Kerala) from classical CHIK cases was undertaken.The phylogenetic analysis was performed using MEGA version 3.1. Clustalx version 1.83 was used to perform the multiple nucleotide and amino acid sequence alignments. For the construction of phylogenetic trees, neighbour-joining algorithm and Kimura 2-parameter distance model were utilized. The reliability of the analysis was evaluated by Bootstrap test with 1000 bootstrap replications. Kerala06 and Kerala07 isolates shared 97.2% nucleotide identity with S-27 (prototype African genotype) and 100% nucleotide identity with Ind-06-TN-1 isolate. Kerala06 and Kerala07 shared 99.9% nucleotide identity with each other. Apart from this nucleotide identity some unique amino acid changes were observed in both Kerala isolates. Three unique substitutions observed earlier for the 2006 Indian isolates, two (T128K& T376M) in Nsp1 region and one (P23S) in capsid were present in both Kerala isolates. Two unique amino acid changes (V583A & L1074S) in Nsp2 region and (K577Q) in E2 region were noted in Kerala07 isolate. The unique amino acid substitutions in Kerala06 were (Y655C) in Nsp2 region, (Q632L & H638P) in E2 region and (H916Q) in E1 region.
