TABLE 1.
Key molecular features and threshold pH of fusion of A(H9N2) viruses used in this study
| Virus name | Abbreviation | Lineage | HAa |
NA | PB2 |
PB1 | PA | pH of fusion | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 183 (173) | 190 (180) | 226 (216) | 227 (217) | 228 (218) | del62-64 | 627 | 701 | 368 | 185 | ||||
| A/Hong Kong/1073/1999 | HK/1073 | G1 | H | E | L | Q | G | no | E | D | I | K | 5.8 |
| A/Hong Kong/33982/2009 | HK/33982 | G1 | H | D | Q | Q | G | no | E | N | I | K | 5.5–5.8 |
| A/Bangladesh/0994/2011 | Bang/0994 | G1 | H | A | L | I | G | no | E | D | I | K | 5.6–5.7 |
| A/Hong Kong/308/2014 | HK/308 | B Y280 | N | T | L | M | G | yes | E | D | V | R | 5.4–5.5 |
| A/Anhui-Lujiang/39/2018 | A-L/39 | B Y280 | N | T | L | M | G | yes | V | D | V | R | 5.4 |
| A/ck/Vietnam/NCVD-18-70-12/2018 | ck/VN/70 | B Y280 | N | T | L | M | G | no | E | D | V | R | 5.5 |
| A/ck/Vietnam/NCVD-NA4V3S5/2018 | ck/VN/NA4 | B Y280 | N | T | L | M | G | yes | E | D | V | R | 5.3–5.4 |
| A/ck/Vietnam/NCVD-18-119-18/2018 | ck/VN/119 | A Y280 | N | A | L | M | G | no | E | D | V | R | 5.3–5.4 |
| A/ck/Vietnam/NCVD-18-167-18/2018 | ck/VN/167 | A Y280 | N | A | L | M | G | no | E | D | V | R | 5.4–5.5 |
a
For HA, H3 numbering is shown, with H9 numbering provided in parentheses.