TABLE 4.
Effects of different immunizations routes with dLOS-CRM conjugate on LOS antibody responses and bacterial clearance in mice
| Routea | Antibody class | GMb titers of antibody against LOS of strain 25238 as determined by ELISA
|
Mean CFU of bacteria recovered/mouseb (range) | Bacterial reductionc (%) | ||||
|---|---|---|---|---|---|---|---|---|
| Nasal wash | Lung lavage fluid | Saliva | Fecal extract | Serum | ||||
| i.n. | IgA | 140 (77-225)**d | 111 (23-530)** | 14 (4-55) | 15 (5-42) | 37 (15-94)* | 4,192 (2,360-7,447)¶¶e | 80 |
| IgG | 37 (23-61) | 73 (13-396)* | 3 | 3 | 47 (17-124)** | |||
| IgM | 3 | 3 | 3 | 3 | 12 (8-20)** | |||
| s.c. | IgA | 3 | 3 | 3 | 3 | 10 | 9,095 (5,403-15,311)¶ | 58 |
| IgG | 12 (4-42) | 217 (36-1,318) | 3 | 6 (2-17) | 5,851 (962-35,587) | |||
| IgM | 3 | 3 | 3 | 3 | 522 (149-1,810) | |||
| Naïve control | IgA | 3 | 3 | 3 | 3 | 10 | 21,437 (16,000-28,723) | 0 |
| IgG | 3 | 3 | 3 | 3 | 10 | |||
| IgM | 3 | 3 | 3 | 3 | 10 | |||
Mice, 16 per group, were i.n. immunized four times at 1-week intervals with 10 μl of PBS containing a mixture of 5 μg of dLOS-CRM and 1 μg of CT or received s.c. injections three times at 2-week intervals with 200 μl of PBS containing 5 μg of dLOS-CRM mixed with Ribi adjuvant or were kept as naïve mouse controls. One week after the last immunization, eight mice from each group were used to collect samples for antibody measurement and ELISPOT assay. The remaining eight mice from each group were challenged with 5.0 × 108 CFU of the M. catarrhalis strain 25238 per ml in a nebulizer. Mouse lungs were collected 6 h postchallenge.
Geometric mean (± SD range) of data from eight mice.
Compared with naïve group.
Statistical significance for comparison with s.c. group: *, P < 0.05; **, P < 0.01.
Statistical significance for comparison with naïve mice: ¶, P < 0.05; ¶¶, P < 0.01.