FIG. 3.

Evolutionary relationship of influenza A virus NP genes. Nucleotides 741 to 1398 (658 bp) of the NP genes were used for phylogenetic analysis. All viruses underlined were isolated from humans. Horizontal distances are proportional to the minimum number of nucleotide differences required to join nodes and sequences. Viruses isolated from parakeets or humans are boxed or underlined, respectively. Numbers at the nodes indicate confidence levels of bootstrap analysis with 1,000 replications as a percentage value. Abbreviations: Pa, parakeet; Qa, quail; HK, Hong Kong; Ck, chicken; Dk, duck; Kor, Korea; Mal, mallard; Ast, Astrakhan; Eq, equine; Bei, Beijing; Anas, Anas acuta; Pri, Primorje; Pg, pigeon.