Table 2.
HI antigenic analysis of influenza A(H1N1)pdm09 viruses.
| Reference A(H1N1)pdm09 viruses | Genetic group | Passage history | No of isolates | Reduction in HI titre compared to homologous titre |
||
|---|---|---|---|---|---|---|
| ≤ 2-fold | 4-fold | ≥ 8-fold | ||||
| A/California/7/2009 | E3/E2 | 57 | 57 | – | – | |
| A/Bayern/69/2009 | MDCK5/MDCK1 | 57 | 52 | 5 | – | |
| A/Lviv/N6/2009 | MDCK4/SIAT1/MDCK3 | 57 | 4 | 41 | 12 | |
| A/Christchurch/16/2010 | 4 | E1/E3 | 57 | – | 2 | 55 |
| A/Astrakhan/1/2011 | 5 | MDCK1/MDCK5 | 57 | 57 | – | – |
| A/St. Petersburg/27/2011 | 6 | E1/E4 | 57 | 57 | – | – |
| A/St. Petersburg/100/2011 | 7 | E1/E4 | 57 | 57 | – | – |
| A/Hong Kong/5659/2012 | 6А | MDCK4/MDCK2 | 57 | 57 | – | – |
| A/South Africa/3626/2013 | 6B | E1/E3 | 57 | 57 | – | – |
| A/Slovenia/2903/2015 | 6B.1 | E4/E1 | 57 | 56 | 1 | – |
| A/Israel/Q-504/2015 | 6B.2 | C1/MDCK2 | 57 | 51 | 5 | – |
E — egg isolate.