FIG. 1.
Immunization with BcfA protects mice against B. bronchiseptica challenge. Mice were immunized intraperitoneally at 0 and 3 weeks with either 10 or 30 μg of BcfA adsorbed to alum or alum only. One week after the second immunization, mice were intranasally challenged with 5 × 105 CFU of RB50 in a 25-μl volume. Mice were sacrificed at 1 day (A) and 6 days (B) postchallenge, and the number of CFU was determined in the nasal septums, tracheas, and lungs. Individual symbols represent a single mouse. The dashed line represents the lower limits of CFU detection. Black bars represent mean colonization of respective groups. A statistical analysis was carried out using the unpaired two-tailed Student t test to compare the CFU obtained from the respective groups of BcfA-immunized mice to that of mice receiving alum. The asterisks indicate the range of the different P values (one asterisk, ≤0.05; two asterisks, ≤0.005; and three asterisks, ≤0.0005).