FIG 8.

Immunoblot analysis of cagM, cagV, and cag3 mutants and requirement of these proteins for T4SS-dependent induction of IL-8 secretion. Marked cagM, cagV, and cag3 mutant strains (containing antibiotic cassettes inserted into these genes), unmarked mutants, and complemented mutants were generated as described in Materials and Methods. (A) Production of CagM, CagV, Cag3, and a control protein (HspB) was assessed by immunoblot analysis. Arrow designates CagV. (B) AGS cells were infected with the indicated strains, and IL-8 secretion was quantified by ELISA of cell culture supernatants. *, P < 0.01 in comparison to results for the parental strain (Student's t test).