Fig. 6
From: The molecular determinants of antigenic drift in a novel avian influenza A (H9N2) variant virus
Evolution of residues 127, 135, 145, 146, 179, 182 and 183 in HA gene of the H9N2 AIV in China from 1994 to 2019. All H9 HA amino acid sequences of China isolates (as of November 2019) were downloaded from GISAID (https://www.gisaid.org) and aligned using MAFFT. Excluding homologous and duplicate sequences, the prevalence of amino acids at each antigenic residue was then assessed