Table 2. HI reactions of H1N1 virus variants with ferret antisera.
| HI titer with ferret antisera
|
||||||||
|---|---|---|---|---|---|---|---|---|
| Virus | 1918 HA | Sw/la/30 | WS/33 | PR/8/34 | USSR/77 | Chili/83 | Tx/91 | New Cal/99 |
| 1918 HA | 2,560 | 1,280 | 320 | 40 | <10 | 10 | 80 | 20 |
| Sw/la/30 | 1,280 | 2,560 | 20 | 320 | 80 | 10 | 80 | 20 |
| WS/33 | <10 | <10 | 640 | 40 | <10 | <10 | <10 | 40 |
| PR/8/34 | 20 | <10 | 160 | 2,560 | 10 | <10 | 10 | 10 |
| USSR/77 | <10 | <10 | 10 | <10 | 1,280 | 20 | <10 | <10 |
| Chili/83 | <10 | <10 | 10 | <10 | 40 | 320 | 20 | 10 |
| Tx/91 | <10 | <10 | 20 | <10 | <10 | <10 | 2,560 | 40 |
| New Cal/99 | 10 | <10 | 10 | 20 | <10 | <10 | 40 | 1,280 |
Serum samples were from ferrets infected with indicated H1N1 viruses. HI titers represent reciprocal of highest dilution of sera inhibiting agglutination of 0.5% chicken erythrocytes by 4 hemagglutination units of virus.