FIG 1.

Prevalence of the G1-like M gene in chicken, quail, and minor poultry (A) and prevalence of BJ/94-like and G1-like M genes in chicken H9N2 viruses (B) in China. The phylogenetic tree of the M gene was generated with all available M sequences from H9N2 viruses isolated from various hosts in China during the period of 1994 to 2015. In the tree, the names of viruses from chicken, quail, minor poultry, and others are shown in red, green, blue, and black, respectively. For each column from left to right, the actual numbers of virus isolates are 67, 183, and 475 (A) and 13, 141, 21, 41, 16, 30, 40, 53, 53, 64, 88, 189, 33, and 6 (along the x axis) (B). In panel B, all HA genes of chicken H9N2 viruses belonged to the BJ/94-like lineage; the G1-like M gene has become predominant in the BJ/94-like viruses through reassortment.