TABLE 3.
Frequencies of amino acids at the positions in HA protein where the mutations were identified in the H7N3 influenza A viruses before and after heterologous vaccination was employed
| H7 position | H3 positiona | Relevant amino acidsb | No. of corresponding amino acids for indicated viruses (yr, no. of isolates)c |
|||||
|---|---|---|---|---|---|---|---|---|
| Italian H7N3 viruses (2002–2004, 41) | Italian H7 viruses (1999–2002, 44) | Netherland H7N7 viruses (2003–2006, 7) | Mexican H7N3 viruses (2012, 3) | Pakistan H7N3 viruses (1995–2004, 16) | China H7N9 viruses (2013, 33) | |||
| 112 | 122 (A) | T/A/S/E | 37/3/0/0 | 33/11/0/0 | 7/0/0/0 | 0/0/3/0 | 16/0/0/0 | 0/32/0/1 |
| 133 | 144 (A) | G/E | 30/11 | 42/2 | 7/0 | 3/0 | 16/0 | 33/0 |
| 151 | 160 (B) | A/T | 23/18 | 28/16 | 7/0 | 3/0 | 16/0 | 33/0 |
| 177 | 186 (B) | G/V | 28/13 | 31/13 | 6/1 | 3/0 | 15/1 | 0/33 |
| 201 | 210 | Q/H/R/L | 28/13/0/0 | 41/0/2/1 | 7/0/0/0 | 3/0/0/0 | 16/0/0/0 | 33/0/0/0 |
a
The alignments between H7 and H3 were performed based on the work of Yang et al. (29), and the antibody binding sites (in parentheses) were annotated by Wilson and Cox (30).
b
Amino acids present in the corresponding position in HA sequences of H7 influenza A viruses.
c
The virus sequences were downloaded from influenza virus resources at GenBank. The corresponding amino acids were counted, and the numbers of predominant residues are in bold.