Colonization of the lungs by B. pertussis. Tlr4-deficient C3H/HeJ and control C3H/HeOuJ mice were subcutaneously (sc) injected with 1/5 human dose (HD) wP, aP, or adjuvant (C), twice before intranasal B. pertussis infection. Three and seven days after challenge lungs were excised, and the number of viable B. pertussis was determined in right lung lobes. Each symbol represents the number of bacteria in the lung of an individual mouse; horizontal lines represent the group average. Non-boxed P-values: compared to the indicated treatment group (same strain and day after infection). Boxed P-values: compared to the wild-type strain (same treatment and day after infection). ANOVA followed by Bonferroni post-hoc test. A single representative experiment of 2 is shown.