Fig 1. Colonization in the nose and lungs of naive and vaccinated mice.

(a) Design of the study. Mice were vaccinated at day 0 (d0) and at day 21 (d21) by subcutaneous (s.c.) injection with DTaP2, DTaP3, DTwP, or mock. Three weeks after the final vaccination (d42), mice were infected intranasally (i.n.) with one of the Prn⁺ or Prn^- strains. Three (d45), seven (d49), and 14 (d56) days after challenge, bacterial load was determined in nose (b) and lung lavage (c). For each treatment group and challenge strain, the bacterial load over time is shown as the median log₁₀ CFU ± interquartile range (n = 5–18 mice per group and time point). Dashed line indicates lower limit of detection.