Figure S1. Phylogenetic tree of the M, NS, PA, NP, PB1, and PB2 segments from

isolates of H7N9. Nucleotide sequences are analyzed using the maximum-likelihood

method. Supporting bootstrap values of greater than 70 are shown. Scale bar indicates

nucleotide substitutions per site. H7N9 viruses isolated from the first, second and

third cluster were marked with filled dot, triangle and square, respectively.