Table 2. Amino acid substitutions identified during serial passages of avian H9N2 virus in guinea pigs.
| Genes | Amino acid position | Wild virus | P3 | P6 | P9 | P12 | P15 |
|---|---|---|---|---|---|---|---|
| PB2 | 195 | D | D | D/Nc | N | N | N |
| PB1 | NCa | NDb | ND | ||||
| PA | NC | ND | ND | ||||
| HA1d | 227 | Q | P | P | P | P | P |
| HA2 | 46 | D | D | D | D | D | E |
| NP | 434 | E | K | K | K | K | K |
| NA | NC | ND | ND | ||||
| M1 | 211 | Q | Q | Q | Q | Q/R | R |
| M2 | NC | ND | ND | ||||
| NS | NC | ND | ND |
aNC, no amino acid changes detected between wild virus and P15 virus.
bND, sequencing not done.
cBold letters denotes two residues at particular amino acid position based on data of sequencing profiles.
dThe amino acid positions of HA1 were as H3 HA numbers.