Gastric Th1 cytokine mRNA expression levels. For 6 to 11 months, gastric tissues (n = 13 to 15 per group) from mice infected with H. pylori, H. muridarum, or H. hepaticus or from HmHp or HhHp mice were evaluated by Q-PCR for expression levels of mRNA for proinflammatory cytokines, all normalized to the expression of the housekeeping gene Gapdh. The y axes represent the mean fold changes (± standard deviations) of the mRNA levels in reference to uninfected controls. HmHp or HhHp mice expressed lower levels of proinflammatory mediators Ifn-γ, Il1-β, and Tnf-α at 6 MPI. Numbers on the y axes represent fold changes of gastric mRNA levels compared to those of sham controls. P values compared to those of the sham controls: *, P < 0.05; **, P < 0.01; ***, P < 0.001.