TABLE 3.
Passive protection of infant rats by preincubation of serotype 3 pneumococci in sera of young rats immunized intranasally with killed Rx1AL− plus CT or in control sera
| Inoculum (CFU/intrathoracic injection) | Serum source | Bacteremia
|
Mortality
|
||
|---|---|---|---|---|---|
| No. bacteremic/total no. (%) | P vs NRS | No. dead/total no. (%) | P vs NRS | ||
| 5 | NRS | 9/10 (90) | 11/11 (100) | ||
| Rats immunized with CT alone | 10/12 (83) | 1.0 | 11/11 (100) | 1.0 | |
| Humans vaccinated with 23-valent PS vaccinea | 0/11 (0) | <0.0001 | 0/11 (0) | <0.0001 | |
| Rats immunized with Rx1/AL− + CT | 1/11 (9) | 0.0003 | 1/11 (9) | <0.0001 | |
| 50–75 | NRS | 12/12 (100) | 12/12 (100) | ||
| Rats immunized with CT alone | 18/22 (82) | 0.27 | 22/22 (100) | 1.0 | |
| Humans vaccinated with 23-valent PS vaccinea | 4/12 (33) | 0.001 | 4/12 (33) | 0.001 | |
| Rats immunized with Rx1AL− + CT | 14/24 (58) | 0.015 | 13/24 (54) | 0.006 | |
a
Human anticapsular antibody: BPIG (hyperimmune globulin obtained from healthy adult volunteers immunized with 23-valent pneumococcal polysaccharide vaccine).