Phylogenetic analysis of the CHIKV partial nsP2, E2 and E1 coding region nucleotide sequences. a) Tandem arrangement of the sequences used for the analysis. Numbers indicate the position with respect to the sequence of S27 strain (AF369024). b) Neighbor-Joining Tree of corresponding sequences of CHIKV strains derived from human clinical samples constructed with 10,000 bootstrap replications. The human and mosquito sequences obtained from the study are marked 'black triangle' and 'black diamond', respectively. GenBank accession numbers and strain names are indicated. Scale bar represents the number of substitutions/site. Sequences of recent Kerala isolates are indicated by '→'.