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Colonization of C57BL/6J and BALB/c Wild-Type and Knockout Mice with Helicobacter pylori: Effect of Vaccination and Implications for Innate and Acquired Immunity

ABSTRACT The gram-negative bacterial pathogen Helicobacter pylori is a major cause of peptic ulcer disease and a risk factor for gastric cancer in humans. Adapted H. pylori strains, such as strain SS1, are able to infect mice and are a useful model for gastric colonization and vaccination studies. In this study we used a streptomycin-resistant derivative of H. pylori SS1 to analyze the colonization behavior and the success of vaccination in wild-type (wt) and various knockout mice of the BALB/c and C57BL/6J genetic backgrounds. We here report that BALB/c interleukin-4 knockout (IL-4−/−) mice are weakly overcolonized compared to the wt strain but that the IL-12−/− knockout results in a strong overcolonization (500%). Unexpectedly, in the C57BL/6J background the same knockouts behaved in diametrically opposed manners. The IL-4−/− mutation caused a 50% reduction and the IL-12−/− knockout caused a 95% reduction compared to the wt colonization rate. For C57BL/6J mice we further analyzed the IL-18−/− and Toll-like receptor 2 knockout mutations, which showed reductions to 66 and 57%, respectively, whereas mice with the IL-10−/− phenotype were hardly infected at all (5%). In contrast, the tumor necrosis factor receptor knockout (p55−/− and p55/75−/−) mice showed an overcolonization compared to the C57BL/6J wt strain. With exception of the low-level infected C57BL/6J IL-10−/− and IL-12−/− knockout mice, all knockout mutants were accessible to a prophylactic vaccination and their vaccination behavior was comparable to that of the wt strains.