Table 2. Amino acid changes observed in 2009 pdm A(H1N1) virus in samples of “I” and “II”.
| Segment | Position | Samples “I” (number of samples) | Samples “II” (number of samples) |
| HA | 145 | S (46) | S (202), L (5) |
| HA | 149 | V (46) | V (183), E (24) |
| HA | 156 | A (46) | A (206), T (1) |
| HA | 185 | D (46) | D (202), N (5) |
| HA | 188 | K (46) | K (187), R (20) |
| HA | 200 | S (37), P (9) | S (207) |
| HA | 203 | A (46) | A (202), T (5) |
| HA | 214 | A (37), T (9) | A (158), T (48), V (1) |
| HA | 220 * | S (46) | T (206), S (1) |
| HA | 222 | R (46) | R (200), K (7) |
| HA | 239 | D (46) | D (204), E (3) |
| HA | 250 | L (46) | L (194), I (13) |
| HA | 291 | D (46) | D (190), N (17) |
| HA | 321 | P (46) | P (196), S (11) |
| HA | 338 | V (37), I (9) | V (206), I (1) |
| HA | 387 | N (32), K (13), R (1) | N (206), D (1) |
| HA | 391 | E (46) | E (145), K (61), G (1) |
| NA | 248 * | N (46) | D (207) |
| NA | 275 | H (46) | H (202)+Y (5) |
| NA | 295 | N (46) | N (206)+S (1) |
Total of samples “I” = 46.
Total of samples “II” = 207.
*The positions of major amino acid substitutions that clearly discriminate between the 2009 pdm influenza viruses identified in samples “I” and those found in samples “II”.