Table 1.
Selected characteristic amino acids of H7N1 subtype AIVs isolated from wild birds.
| Gene | Key residues | Comments | The isolates | ||
|---|---|---|---|---|---|
| CP/XH/420/10 (H7N1) | BP/HuN/414/10 (H7N1) | A/Shanghai/13/2013 (H7N9) | |||
| HA (H3 numbering) | Cleavage sites | Characteristic of low-pathogenic in chickens (Steinhauer, 1999) | PELPKGR↓GLFGAI | PELPKGR↓GLFGAI | PEIPKGR↓GLFGAI |
| Ser138Ala(S-A) | Favor mammalian adaptation (Fan et al., 2015) | A | A | A | |
| Thr160Ala(T-A) | Increased affinity toward α-2,6-linked sialic acid receptor (Fan et al., 2015) | A | A | A | |
| Gln226Leu(Q-L) | Increased affinity toward α-2,6-linked sialic acid receptor (Yamada et al., 2006) | Q | Q | I | |
| Gly228Ser(G-S) | Increased affinity toward α-2,6-linked sialic acid receptor (Yamada et al., 2006) | G | G | G | |
| PB2 | Glu627Lys(E-K) | Mammalian adaptation (Li et al., 2005) | E | E | K |
| Asp701Asn(D-N) | Mammalian adaptation (Li et al., 2005) | D | D | D | |
| M2 | Ser31Asn(S-N) | Amantadine resistance (Lee et al., 2008) | S | S | N |
| NS1 | Pro42Ser(P-S) | Increased virulence in mice (Jiao et al., 2008) | S | S | S |