Author affiliations: National Institute of Animal Health, Kannondai, Japan (Y. Uchida, M. Mase, T. Saito, Y. Yamamoto, K. Nakamura, K. Tsukamoto, S. Yamaguchi); Japan Wildlife Research Center, Taito-ku, Tokyo, Japan (K. Yoneda); Akita Animal Hygiene Service Center of Akita Prefecture, Akita, Japan ( A. Kimura, T. Obara, S. Kumagai);
Figure 2. Phylogenetic tree constructed based on the hemagglutinin (HA) 1 region (966 bp) of the HA gene of the highly pathogenic avian influenza viruses (H5N1). Clade designation follows the criteria proposed by the World Health Organization/World Organisation for Animal Health/Food and Agriculture Organization H5N1 Evolution Working Group (8). Representative strains of the previous highly pathogenic avian influenza outbreaks in Japan are in boldface. Scale bar represents number of nucleotide substitution per site.
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