Figure 1

CiaD and Erk 1/2 are required for maximal C. jejuni invasion. A. The C. jejuni ciaD mutant is deficient in maximal invasion of INT 407 cells. Invasion of INT 407 cells was assessed using a gentamicin protection assay as outlined in Methods. B. Maximal activation of Erk 1/2 requires CiaD. INT 407 cells were infected with the various isolates of C. jejuni for 45 min and cell lysates were evaluated via immunoblot. Blots were probed with phospho-specific antibodies to Erk 1/2. All blots were stripped and re-probed with an α-Erk 1/2 antibody. Molecular mass size standards, in kilodaltons (kDa), are indicated on the left. Densitometry of pErk 1/2 is shown as the ratio of p-Erk 1/2 to t-Erk 1/2 for each sample. C. Erk 1/2 kinase activation is required for maximal bacterial invasion. PD98059, an inhibitor of Erk 1/2 activation, was added to INT 407 cells for 30 min prior to inoculation with a C. jejuni wild-type strain, and bacterial invasion was assessed. The asterisk indicates a significant reduction compared to the value obtained for the C. jejuni wild-type strain, as judged by one-way ANOVA followed by post-hoc Dunnett’s analysis (P < 0.01). N.S. indicates no significant difference. Results are shown as means ± SEM.