Identification of Pathogenicity Island Genes Associated with Loss of Type IV Secretion Function during Murine Infection with Helicobacter pylori.

Chronic colonization in animal models often leads to downregulation of the type IV secretion system (T4SS), typically by recombination in , which is an essential T4SS gene. However, 17 other pathogenicity island (PAI) genes, as well as some non-PAI genes, are also essential for T4SS function. To get a more complete picture of how regulates the T4SS during animal colonization, we examined in 534 mouse-passaged isolates that lost T4SS function, defined as a normalized interleukin-8 (IL-8) value of <0.