Phylogenetic analysis of the A) HA1 fragment of hemagglutinin, HA gene (885nt) and B) neuraminidase, NA gene (1,404nt) of influenza B viruses.

<p>Trees were constructed using the Neighbor-Joining method. Numbers at the nodes indicate confidence levels of bootstrap analysis with 1,000 replicates as percentage value. Amino acid substitutions that characterized a particular branch are indicated on the left side node. Vaccine strains are italicized and in red. Reference strains are boldfaced.