Figure 2. Maximum-likelihood tree showing the phylogenetic relationship of A) dengue virus serotype 2 (DENV-2) and B) DENV-3 from Singapore and global isolates based on the envelope protein gene. EHI, sequence data generated at Environmental Health Institute; new clade, isolates obtained in 2007 and later; old clade, isolates obtained before 2007. Numbers on branches represent bootstrap percentages; only those >80% are shown. Scale bars indicate substitutions per site.