FIG 2.

Neighbor-joining phylogenetic tree of the neuraminidase (NA) and internal genes of highly pathogenic avian influenza A(H5N1) viruses constructed in MEGA5. Viruses collected in 2012-2013 are denoted with an asterisk. Sequences were aligned using MUSCLE; amino acid differences at branch nodes indicate substitutions relative to reference strain A/Vietnam/1203/2004 for the NA gene and A/Hubei/1/2010 for the internal genes. Mutations to the right of each strain name indicate amino acid changes found only in that individual virus. Underlined amino acid substitutions indicate previously recognized molecular markers and/or markers of note as listed in the H5N1 Genetic Changes Inventory (24). Branches on the tree with sequences from human cases are in bold. Bootstraps greater than 50 generated from 1,000 replicates are shown at branch nodes. The scale bar represents the number of nucleotide substitutions per site.