Table 3. The anti-RTB-ATB IgG antibody titers of sera after each immunization and challenge trial.
| Immunization time interval | Dose of RTB-ATB | i.p. injection | s.c. injection | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Vaccination 1 |
Vaccination 2 |
Vaccination 3 |
Vaccination 4 |
7 d after challenge |
Vaccination 1 |
Vaccination 2 |
Vaccination 3 |
Vaccination 4 |
7 d after challenge |
||
| І | 15 μg | 102 | 104 | 105 | 106 | 107 | 102 | 103 | 104 | 106 | 107 |
| 25 μg | 102 | 104 | 106 | 107 | 108 | 102 | 104 | 105 | 106 | 107 | |
| Π | 15 μg | 102 | 104 | 105 | 106 | 107 | 102 | 103 | 104 | 106 | 107 |
| 25 μg | 102 | 105 | 106 | 107 | 108 | 103 | 103 | 105 | 107 | 108 | |
10 mice per group. Vaccination 1–4: The antibody titers were measured 7 d after each vaccination. Seven days after challenge: The antibody titers were measured 7 d after challenge with native toxins. Titer was considered as positive when the values of OD450 were greater than 2.1-fold negative control. P > 0.05 indicated no significant titer difference among test groups, while P < 0.05 indicated obvious differences between test groups and negative control groups.