Table 2. Protection test of ND vaccine alone or mixture of ND and IBD vaccines against ND virus challenge (Experiment 4).
| Group | ND vaccine |
IBD vaccine |
Dose of challenge ND virus |
Mortality | HI antibody titer (geometric mean) |
Result | |
|---|---|---|---|---|---|---|---|
| At challenge | 14 days after challenge |
||||||
| 1 | - | - | 107 | 100% (9/9) | <2 | - | Death |
| 2 | - | - | 105 | 100% (9/9) | <2 | - | Death |
| 3 | + | - | 107 | 0% (0/10) | 8 | 90.5 | Protection |
| 4 | + | - | 105 | 0% (0/10) | 12.1 | 84.4 | Protection |
| 5 | + | + | 107 | 0% (0/10) | 13.0 | 955.0 | Protection |
| 6 | + | + | 105 | 0% (0/10) | 6.5 | 181.0 | Protection |