Table 1.
Comparison of amino acids in HA receptor-binding site of human, avian, and swine H2 influenza virus isolates
| Virus strains | HA receptor-binding residues |
|||||
|---|---|---|---|---|---|---|
| 138/148 | 190/200 | 194/204 | 225/235 | 226/236 | 228/238 | |
| Avian consensus | A | E | L | G | Q | G |
| Mallard/2003/H2N3 | A | E | L | G | Q | G |
| Sw/4296424 | A | E | L | G | L | G |
| Sw/2124514 | A | E | L | G | L | G |
| Human consensus | A | E | L | G | L | G/S |
| Davis/1/57 | A | E | L | G | L | G |
| Albany/7/57 | A | E | L | G | L | G |
| RI/5+/57 | A | E | L | G | L | S |
| Albany/6/58 | A | E | L | G | L | S |
| Ohio/2/59 | A | E | L | G | L | S |
| Berlin/3/64 | A | E | L | G | L | S |
Under HA receptor-binding residues, the H3 numbering system is used for numbers before the slash, and the H2 numbering system is used for numbers after the slash. The Davis/1/57 and Albany/7/57 viruses were isolated earlier in the human H2 pandemic when compared to the other H2 human viruses listed here.