Fig. 4

E-gene based phylogeny of DENV illustrating different types of virus strains circulated during 2013-2014. Phylogenetic analysis was performed in MEGA6 program [32] using the maximum-likelihood method based on the general time reversible model with gamma distribution and invariant sites. The robustness of the original tree was tested with 1000 bootstrap replications. a. DENV-1 and DENV-2 strains circulated in Singapore in both years have been highlighted in red and blue respectively. b. DENV-3 and DENV-4 strains circulated in Singapore in both years have been highlighted in green and purple respectively. The major groups summarized in Table 1 are shown in triangular cartoons. Each taxon is named with sample ID/NCBI accession number, reported year, country and genotype information. Numbers on branches are bootstrap support values. GI, GII, and GIII = genotypes I, II and III; cosmo = cosmopolitan genotype