Fig. 1. Phylogenetic analysis of the HA genes of H9 subtype avian influenza viruses isolated from poultry in Korea. The maximum likelihood tree was constructed using a general time-reversible nucleotide substitution model, with a gamma distribution of among-site rate variations and bootstrap analysis (n = 1,000). A/turkey/Wisconsin/1/1966(H9N2) was used as an out-group. All positions containing gaps and missing data were eliminated. There were a total of 1,549 positions in the final dataset. Representative sequences of viruses are listed in bold. The reported isolates are marked with a black dot. Bootstrap scores < 70% are hidden.