TABLE 1.
HA-stabilizing mutations listed by amino acid position
| Mutation | Structural region | Virus plaque(s)a |
|---|---|---|
| I29 M | Stalk | L133, P193 |
| D95*G | Globular head receptor-binding domain | P33 |
| D101N | Globular head receptor-binding domain | L153 |
| A218V | Globular head receptor-binding domain | L1 |
| S221P | Globular head receptor-binding domain | P11, P32,3, P41, P52,3 P81, P92, P193, P203 |
| M230V | Globular head receptor-binding domain | L153 |
| R397 M | Stalk | L6, L18, P14, P18 |
| L418I | Stalk | L53, L17, P15 |
| L427I | Stalk | L19, P11 |
| M431L | Stalk | P193 |
| R456K | Stalk | P41 |
a
L1 to L20, plaques derived from virus library; P1 to P20, plaques derived from parental sample. Superscript numbers: 1, sequencing revealed reversion from L226 to Q226; 2, sequencing revealed both L226 and Q226; 3, sequencing revealed both the wild-type amino acid and the amino acid identified after heat treatment (for example, sequence analysis of plaque P19 revealed both isoleucine and methionine at position 29).