Differences in the HA amino acid sequence compared to the VN/1203 master sequence.

(1)HA1 numbering starts with the first amino acid downstream of the signal peptide with D as the first residue (Aichi numbering);(2)amino acids exposed on the surface are printed in bold (equivalent to yellow marked molecules in Fig. 5);(3)VN, A/Vietnam/1203/2004; IN, A/Indonesia/5/05; AN, A/Anhui/1/2005; CE, A/Chicken/Egypt/3/2006; TT, A/turkey/Turkey/1/2005;(4)first R residue of polybasic cleavage site;(5)numbering of the HA2 starts downstream of the polybasic cleavage site with G as the first residue.