TABLE 3.
Animal challenge experiment
| Groupa | No. of injections | Inoculation typeb | Challenge strainc | No. of duck deaths | Protection rate (%)d |
|---|---|---|---|---|---|
| 1 | 1 | Yb2ΔpncA | Yb2 | 2 | 80 |
| 2 | 1 | Saline | Yb2 | 10 | 0 |
| 3 | 2 | Yb2ΔpncA | Yb2 | 1 | 90 |
| 4 | 2 | Saline | Yb2 | 10 | 0 |
a
Each group contained 10 ducks.
b
Seven-day-old ducks were immunized once or twice. Ducks that received two immunizations were immunized 7 days apart.
c
The challenge dose was 10 times the LD50.
d
The protection rate was calculated as follows: [1 − (no. of dead ducklings per group/total no. of ducklings per group)] × 100.