TABLE 4.
Protection of BALB/c mice after active immunization with pneumococcal antigensa
| Antigen | Amtb | No. alive/total no.c | % Survival | P (versus MSA-immunized mice)c |
|---|---|---|---|---|
| Ctrl | NA | 1/8 | 13 | NA |
| PsaA | 250 pmol | 1/5 | 20 | 0.51 |
| PpmA | 250 pmol | 3/13 | 23 | 0.38 |
| PspA | 100 pmol | 4/5 | 80 | 0.031* |
| T3-PS | 0.5 μg | 9/9 | 100 | 0.0004* |
a
At 2 weeks after the second immunization with the indicated antigens, BALB/c mice were challenged with 500 CFU of live S. pneumoniae strain A66.1 (type 3) injected i.p.
b
Mice were immunized with the indicated antigens on days 0 and 11. T3-PS is type 3 capsular PS. Control (Ctrl) mice were immunized twice with MSA.
c
Survival of mice was monitored for 15 days after challenge with S. pneumoniae. *, Statistically significant overall survival (P < 0.05) compared to the overall survival for control mice, as calculated by using the Fisher exact test.