Figure 4. IL-8 induction capacity of selected site-directed double motif deletion mutants and single amino acid substitutions in CagL in comparison to the parental strain H. pylori SU2.

AGS cells were infected for 22 h (MOI = 50) with isogenic chromosomal HP0539/cagL mutants as indicated. Culture supernatants of coincubated AGS cells were tested for IL-8 by ELISA. The level of IL-8 secretion induced by contact with the SU2 parental strain (wt) was set to 100%, and corresponding percent values of the cagL motif mutants are depicted. For each mutant, results were obtained from two independently generated and validated clones. The data shown are results (mean and SD) from triplicate measurements of at least four independent experiments. Significance of differences towards the parental strain was calculated by student’s t-test shown as black asterisks above each bar: ***p < 0.01; **p < 0.02; *p < 0.05. Plus and minus signs at the right side of the figure indicate normal to slight reduction [++], clear reduction [+], and strong reduction [−].