FIG 1.

Maximum likelihood tree of the HA1 genes of H5 highly pathogenic avian influenza A(H5) viruses. The nearest reassortant WHO candidate vaccine viruses (CVV) for each clade are colored red. Amino acid differences at branch nodes indicate shared HA1 substitutions relative to the reference strains. Mutations listed to the right of each strain name indicate amino acid changes found only in that individual virus. Mutations highlighted with underlining indicate previously recognized molecular markers. Branches on the tree with HA sequences from human cases are colored red. Bootstraps with values greater than 50 generated from 1,000 replicates are shown at branch nodes. The scale bar represents the number of nucleotide substitutions per site.