FIG. 4.

Kinetics of infection with the Y. pseudotuberculosis Δhfq strain. Mice were inoculated intragastrically with wild-type or Δhfq Y. pseudotuberculosis (10⁷ CFU), and after 2, 4, 6, and 9 days, CFU per gram of tissue in the spleen, visible Peyer's patches, mesenteric lymph nodes, and small intestine were determined. Graphs show bacterial counts from 3 combined experiments. Each point represents CFU/g recovered from a single animal (○, wild-type strain; □, Δhfq strain). A dashed line indicates the limit of detection. A solid line indicates the median of CFU recovered. Symbols below the limit of detection represent mice that survived but did not have detectable numbers of bacteria. Statistical significance was calculated by the Mann-Whitney U test.