FIG. 1.
B. pertussis colonization of naive and immunized mice. C57BL/6 mice were inoculated with 5 × 105 CFU of B. pertussis (Bp) or B. parapertussis (Bpp). Immunized and naive mice were challenged 28 days later with 5 × 105 CFU of a nalidixic acid-resistant strain of B. pertussis and sacrificed 3 days after secondary inoculation for the quantification of bacterial numbers in the nasal cavities (A), tracheae (B), and lungs (C). Values are expressed as the log10 means ± standard deviations (SD). For day 3 colonization levels, the difference between each individual value and the mean log10 CFU approximately 10 min after inoculation in the nasal cavities (D), tracheae (E), and lungs (F) was calculated. These data are represented as the mean changes in log10 CFU ± SD. *, P < 0.05; **, P < 0.01 (compared to naive mice).