FIG. 1.

Protection of mice against intranasal challenge with B. pertussis. (A) Mice were immunized intraperitoneally on days 0 and 28 with ACV alone, a CyaA form alone (25 μg/mouse), or ACV plus a CyaA form at 25 μg/mouse. Mice injected with PBS served as negative controls. Mice were challenged intranasally with B. pertussis 18.323 on day 42. Five mice from the PBS control group were sampled at 2 h postchallenge for enumeration of bacteria in lungs and tracheas (gray bar). All remaining mice immunized with the different CyaA forms alone (black bars) or with ACV plus the different CyaA forms (white bars) and mice from the PBS control group (white bars) were sampled at 7 days postchallenge. (B) Mice were immunized intraperitoneally on days 0 and 28 with ACV alone or with ACV plus graded doses (6.25, 12.5, and 25 μg per mouse) of CyaA*. Mice injected with PBS served as negative controls. Mice were challenged intranasally with B. pertussis 18.323 on day 42. Five mice from the PBS control group were sampled at 2 h postchallenge for enumeration of bacteria in lungs and tracheas (gray bar). All remaining mice immunized with ACV plus graded doses of CyaA* and mice from the PBS control group were sampled at 7 days postchallenge. Results represent the means of bacterial counts for five mice per group plus the standard errors of the means (SEM). †, P < 0.05 (group versus ACV-only group [ANOVA]).