FIG 7.

The ability of the dpr mutant to colonize the nasopharynx is severely impaired. (A) Groups of 5 or 10 mice were challenged intranasally with either the RT or KO strain, and their nasal colonization densities were determined at different time points. Colonization densities of the RT and KO strains at each time point were compared by the Mann-Whitney U test. (B) Competition between RT and KO strain in mice. Mice were intranasally challenged with 10⁷ CFU of a 1:1 ratio of RT and KO strains, and samples were taken at days 1, 3, and 7. Total numbers of CFU were determined by growth on BAP. The absolute quantity of strain-specific genomic DNA in a sample was determined using strain-specific primer sets and then used to calculate the ratio of the two strains in the NP. No KO strain was detected at any time point.