Role of HtrA in clinical symptoms and colonic histopathology in C. jejuni infected infant mice. Immediately after weaning, infant mice were perorally infected with C. jejuni NCTC11168 (WT, closed circles) or the mutant strain NCTC11168∆htrA (∆htrA, open circles). Uninfected animals (Naïve; open diamonds) served as negative controls. Seven days following C. jejuni infection (A) occurrence of blood in fecal samples and (B) histopathological changes in H&E stained colonic paraffin sections were assessed by applying standardized clinical and histophathological scoring systems, respectively. Means (black bars) and numbers of analyzed animals (in parentheses) or absolute and relative (in %) numbers of positive samples out of the total number are indicated. Data shown were pooled from three independent experiments.