Table 1.
Amino acid polymorphisms of the BXA binding domain in PA from human and avian influenza A viruses.
| Influenza virus strain | Subtype | PA amino acid positiona | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 20 | 23 | 24 | 34 | 37 | 38 | 41 | 80 | 108 | 119 | 130 | 134 | 199 | ||
| A/Anhui/1/2013 | H7N9 | A | E | Y | K | S | I | H | E | D | E | Y | K | E |
| A/duck/Japan/AQ-HE28-3/2016 | H7N9 | A | E | Y | K | S | I | H | E | D | E | Y | K | E |
| A/duck/Japan/AQ-HE29-22/2017b | H7N9 | T | E | Y | K | S | I | H | E | D | E | Y | K | E |
| A/duck/Japan/AQ-HE30-1/2018b | H7N3 | A | E | Y | K | A | I | H | E | D | E | Y | K | E |
| Human influenza viruses isolated (As of October 24, 2018)c | H7N9 | A (91.5) |
E (100) |
Y (100) |
K (100) |
S
(99.9) |
I (100) |
H (100) |
E (100) |
D (100) |
E (100) |
Y (100) |
K (100) |
E (99.8) |
| H1N1 | A (99.3) |
E (100) |
Y (99.9) |
K (100) |
A (100) |
I (99.9) |
H (100) |
E (100) |
D (100) |
E (100) |
Y (100) |
K (100) |
E (100) |
|
| H3N2 | A (98.3) |
E (100) |
Y (100) |
K (100) |
A (100) |
I (100) |
H (100) |
E (100) |
D (100) |
E (100) |
Y (100) |
K (100) |
E (100) |
|
| H5N1 | A (85.2) |
E (100) |
Y (100) |
K (100) |
A (100) |
I (100) |
H (100) |
E (100) |
D (100) |
E (100) |
Y (100) |
K (100) |
E (100) |
|
aThe indicated amino acids have been previously shown to be involved in BXA binding to the active center of the endonuclease domain in the PA subunit (residues 20, 24, 34, 37, 38, 41, 80, 108, 119, 130, and 134) and associated with reduced susceptibility to BXA (residues 23, 37, 38 and 199) as reported previously32. The amino acids different from the consensus sequence of human influenza A viruses are highlighted in boldface and underlined. bHighly pathogenic avian influenza viruses. cThe consensus sequences were determined by alignment analysis with the full-length PA sequences obtained from the National Center for Biotechnology Information (NCBI) and Global Initiative on Sharing All Influenza Data (GISAID) on October 24, 2018. Each number shown in parentheses represents frequency (%) of the most frequent variants among 1,094, 10,312, 13,185 and 196 of PA sequences from H7N9, H1N1, H3N2 and H5N1, respectively.