Table 2. Serological comparison in the antibody responses reacted with the pH1N1 isolates with various amino acid substitutions at different antigenic sites by hemagglutination inhibition (HI) tests.
| Virus antigen | Amino acid changes | HI Serotiters of Anti-pH1N1 | ||||||
| Six human serum samples | pH1N1 immune sheep serum2 | |||||||
| 0101 | 020 | 030 | 035 | 053 | 063 | |||
| A/California/07/2009 (NYMC X-179A) | S203S D222D E374E N125N K142K G170G | 6404 | 1280 | 640 | 1280 | 1280 | 640 | 2560 |
| A/Taiwan/NTU4223/2009 (7/1/2009) | S203T D222G E374E | 640 | 640 | 320 | 1280 | 640 | 320 | 2560 |
| A/Taiwan/NTU6118/2009 (9/8/2009) | S203T E374E G170R | 320 | 640 | 320 | 640 | 640 | 320 | 5120 |
| A/Taiwan/NTU025/2010 (1/6/2010) | S203T E374K | 640 | 1280 | 640 | 1280 | 640 | 640 | 5120 |
| A/Taiwan/NTUD252/2010 (6/7/2010) | S203T E374K G170R N125D | 640 | 640 | 320 | 1280 | 640 | 320 | 5120 |
| A/Taiwan/NTUA1281/2010 (6/12/2010) | S203T E374K G170R | 640 | 640 | 320 | 1280 | 640 | 320 | 2560 |
| A/Taiwan/NTUT105/2010 (8/2/2010) | S203T E374K N125D K142R | 640 | 640 | 320 | 640 | 640 | 320 | 5120 |
| Pandemic A/H1N1 control antigen 3 | 5120 | |||||||
1
ID numbers of the tested human serum samples.
2
ATCC IRR FR188 and.
3
ATCC IRR FR-187 in the 2010–2011 WHO Influenza Regent kit for diagnosis of influenza virus from the WHO Collaborating Centers for Surveillance, Epidemiology and control of Influenza at the U.S. Centers for Disease Control and Prevention.
4
HI serotiters: The highest dilution of human serum samples showed complete inhibition of 4 HA units of pH1N1 viruses.