FIG. 3.

Time course of respiratory tract colonization by wild-type and mutant B. pertussis strains. (A) Schematic of strains used in this experiment. Bvg⁺ phase bacteria normally express adhesins (solid bars) and toxins (solid circles), while Bvg⁻ phase bacteria express vrg6 (open bars) and other BvgR-regulated factors (open circles) and possibly other, non-BvgR-regulated vrg genes (not shown). wt, wild type. (B) Respiratory tract colonization. Mice were inoculated intranasally with 50 μl of PBS containing 5 × 10⁴ CFU of the indicated strains, and the numbers of CFU present in the nasal cavity, trachea, and lungs were determined at the indicated times postinoculation. Each symbol represents the mean number of CFU recovered from three animals. Error bars represent ±1 standard error. Dashed lines indicate the lower limit of detection. ∗, P < 0.05.