TABLE 1.
Effect of PA dose on anti-PA Ab generation after primary and secondary immune responsea
| PA dose (μg) | Response on day of booster (GMT ± SD no. of [responders/total])
|
Response 14 days after booster (GMT ± SD [no. of responders/total])
|
||||||
|---|---|---|---|---|---|---|---|---|
| All sera
|
Positive sera
|
All sera
|
Positive sera
|
|||||
| Anti-PA Ab | Neutralizing Ab | Anti-PA Ab | Neutralizing Ab | Anti-PA Ab | Neutralizing Ab | Anti-PA Ab | Neutralizing Ab | |
| 25 | 10,908 ± 1.47 (13/13) | 4,525 ± 0.61 (13/13) | 10,908 ± 1.47 | 4,525 ± 0.61 | 38,000 ± 0.22 (10/10) | 15,222 ± 0.21 (10/10) | 38,000 ± 0.22 | 15,222 ± 0.21 |
| 2.5 | 60 ± 1.76 (4/40) | <50 (0/40) | 257 ± 1.13 | 936 ± 11.33 (7/11) | 621 ± 9.51 (7/11) | 4,997 ± 2.48 | 2,625 ± 3.42 | |
| 1 | <50 (0/32) | <50 (0/32) | 381 ± 6.48 (8/10) | 331 ± 4.26 (7/10) | 975 ± 4.22 | 673 ± 2.05 | ||
| 0.5 | <50 (0/32) | <50 (0/32) | 100 ± 2.53 (5/11) | 56 ± 1.32 (2/11) | 230 ± 2.14 | 100 ± 1 | ||
| 0.25 | <50 (0/32) | <50 (0/32) | <50 (0/12) | <50 (0/12) | ||||
a
Two weeks after the primary immunization, animals were boosted with the same dose of the PA-based vaccine. Ab titers to PA (ELISA) and neutralizing Abs were determined 14 days after the first immunization (at the day of boosting) and 14 days after the booster as described in Materials and Methods.