Lung pathology. Tlr4-deficient and control mice were sc injected with 1/5 HD wP, aP, or adjuvant (C), twice before intranasal B. pertussis infection. Three days after infection the left lung lobes were excised. H&E staining. Histological lesions were semi-quantitatively scored as absent (0), minimal (1), slight (2), moderate (3), strong (4), or severe (5), respectively. Each symbol represents an individual mouse; horizontal lines represent the group average. Non-boxed P-values: compared to the indicated group (same strain). Boxed P-values: compared to the wild-type strain (same treatment). Mann-Whitney U test. A single representative experiment of 2 is shown.