Table 3.
ELISA reactivity of conjugate-induced rabbit serum IgG evaluated with corresponding homologous LOS and the wild type O35E LOS
| Immunogena | Injection no. | Geometric mean (rabbit 1, rabbit 2) of ELISA unitsb |
|
|---|---|---|---|
| Binding to homologous LOS | Binding to O35E LOS | ||
| O35E dLOS-TT | 0 | 1 (1, 1) | 1 (1, 1) |
| 2 | 2187 (2187, 2187) | 2187 (2187, 2187) | |
| 3 | 6561 (6561, 6561) | 6561 (6561, 6561) | |
| O35Elgt5 dLOS-TT | 0 | 1 (1, 1) | 1 (1, 1) |
| 2 | 729 (729, 729) | 243 (243, 243) | |
| 3 | 2187 (2187, 2187) | 140 (243, 81) | |
| O35EgalE dLOS-TT | 0 | 1 (1, 1) | 1 (1, 1) |
| 2 | 16 (27, 9) | 16 (9, 27) | |
| 3 | 27 (27, 27) | 140 (243, 81) | |
| O35E dLOS-TT + Adjuvant | 0 | 1 (1, 1) | 1 (1, 1) |
| 2 | 6561 (6561, 6561) | 6561 (6561, 6561) | |
| 3 | 19683 (19683, 19683) | 19683 (19683, 19683) | |
| O35Elgt5 dLOS-TT + Adjuvant | 0 | 1 (1, 1) | 1 (1, 1) |
| 2 | 3788 (2187, 6561) | 729 (729, 729) | |
| 3 | 11364 (6561, 19683) | 729 (729, 729) | |
| O35EgalE dLOS-TT + Adjuvant | 0 | 1 (1, 1) | 1 (1, 1) |
| 2 | 243 (81, 729) | 243 (81, 729) | |
| 3 | 11364 (6561, 19683) | 1263 (729, 2187) | |
| dLOSs + TT + Adjuvant | 0 | 1 (1, 1) | 1 (1, 1) |
| 2 | 1 (1, 1) | 1 (1, 1) | |
| 3 | 3 (3, 3) | 3 (3, 3) | |
Two rabbits per group were injected subcutaneously (1 dose every 4 weeks, 3 doses total) with dLOS-TT (50 μg of carbohydrate each rabbit) with or without Sigma Adjuvant System. Two rabbits as controls were injected simultaneously with a mixture of dLOSs from O35E, O35Elgt5, and O35EgalE, and TT (50 μg of each for one rabbit) plus the adjuvant. The rabbits were bled before the immunization and 2 weeks after each injection.
ELISA units were based on a reference rabbit serum against the whole cells of strain O35E, O35Elgt5, or O35EgalE, respectively. Each homologous LOS was employed as a coating antigen for its corresponding dLOS-TT-elicited sera and the O35E LOS was also used as a coating antigen for O35Elgt5 or O35EgalE dLOS-TT-elicited sera.