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HA1 substitutions identified at putative antigenic sites on the HA trimeric structure. Amino acid differences between the consensus sequence of each clade and the sequence of the nearest poultry vaccine virus are displayed for clade 1.1.2 versus A/Vietnam/1203/2004 (A), clade 2.3.2.1c versus A/duck/Guangdong/S1322/2010 (Re-6) (B), clade 2.3.4.4 versus A/Anhui/1/2005 (Re-5) (C), and clade 7.2 versus A/chicken/Shanxi/2/2006 (Re-4) (D).
