TABLE 3.
Neutralization titersa of Stx1 in sera from mice injected with E. coli O157 O-SP conjugated with Stx1B
| Immunogen | Serum | Titerb |
|---|---|---|
| OSP-AH-Stx1B | 2a | 10,000 |
| 2b | 12,000 | |
| 2c | 6,400 | |
| 2d | 12,000 | |
| 2e | 15,000 | |
| 2f | 16,000 | |
| 2g | 1,000 | |
| 2h | 6,400 | |
| 2i | 4,000 | |
| 2j | >20,000 | |
| Geometric mean | 8,040* | |
| OSP-Stx1B | 5a | 15,000 |
| 5b | 18,000 | |
| 5c | >20,000 | |
| 5d | 12,000 | |
| 5e | 18,000 | |
| 5f | 16,000 | |
| 5g | >20,000 | |
| 5h | 16,000 | |
| 5i | 16,000 | |
| 5j | 4,000 | |
| Geometric mean | 14,400** |
a
Neutralization of Stx1 or Stx2 was measured by using HeLa cell monolayers incubated with dilutions of 100 pg of toxin/ml of serum. Sera from mice immunized with saline or LPS alone showed titers of <10. None of the sera showed neutralization of Stx2 (titers were <10). The titers are the highest serum dilutions to yield 50% neutralization.
b
∗∗ versus ∗, P < 0.03.