FIG. 8.

Semiquantitative TNF-α and β-actin RT-PCRs were performed on RNA isolated from colons of uninfected mice or mice orally challenged with wild-type or ΔnleH C. rodentium. Median TNF-α levels (measured as a ratio of TNF-α to β-actin) in C. rodentium-infected mice were considered the basal level of activation by wild-type bacteria in each experiment and taken as 100%. All TNF-α/β-actin ratios were compared to this and expressed as a percentage of the median TNF-α level during wild-type infection. GeneTools (Syngene) was used for densitometric analysis. Two repetitions, each using four or five mice per group, were conducted and graphed. The one-way ANOVA Bonferroni multiple-comparison test was used to determine significance, as the three groups had normal distributions. ***, P < 0.001.