Figure 5

Phylogenetic tree of the NA gene sequences of influenza B viruses. NA sequences of influenza B viruses were compared with WHO recommended candidate vaccine (▲) and reference strains. The phylogeny was reconstructed using Neighbor-Joining (NG) method. Bootstrap values (>70%) and amino acid substitutions are mapped to key branches. Yamagata-lineage (blue), Victoria-lineage (green) are indicated.