FIG. 5.
Naïve serum survival of B. bronchiseptica (RB50) and B. parapertussis (CN2591) wild-type strains and O antigen mutants (RB50Δwbm and CN2591Δwbm, respectively) compared to survival of BP536 B. pertussis. All five strains were grown to the mid-log phase in SS broth (liquid culture). Groups of four C57BL/6 mice were infected intranasally with 5 × 105 CFU of BP536, RB50Δwbm, or CN2591Δwbm and recovered from the lungs at 5 days postinoculation (Day 5 Lung). The bacteria were diluted to a concentration of 1 × 104 CFU/ml and treated with 90% naïve rabbit serum for 1 h at 37°C. Serum resistance is expressed as the percentage of bacteria that survived; the error bars indicate standard deviations. All samples were run in triplicate. The data are representative of the results of three separate experiments. Two asterisks indicate that the P value was <0.001 when the data were compared to the data for the corresponding in vitro-grown controls.