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AIM: To evaluate whether attenuated Salmonellatyphimurium producing Helicobacter pylori ( H pylori) urease subunit B (UreB) could induce systemic immune responses against H pylori infection.METHODS: Attenuated S. typhimurium SL3261 was used as a live carrier of plasmid pTC01-UreB, which encodes recombinant H pylori UreB protein. Balb/c mice were given oral immunization with two doses of SL3261/pTC01-UreBat a 3-wk interval. Twelve weeks after oral immunization of mice, serum IgG antibodies were evaluated by ELISA assay. Gamma interferon (IFN-γ) and interleukin 10 (IL-10)in the supatant of spleen cell culture were also assessed by ELISA.RESULTS: After oral immunization of mice, serum specific IgG antibodies against UreB in vaccine group were much higher than that in PBS and native Salmonella SL3261control groups (A450, 0.373±0.100 vs 0.053±0.022, 0.142±0.039, respectively, P＜0.01). Moreover, IFN-γ in vaccine group was on average 167.53±29.93 pg/mL, which showed a significant increase vs that of PBS control group (35.68±3.55 pg/mL, P＜0.01). There was also a tremendous increase of IL-L0 in vaccine group compared to PBS and SL3261 control groups (275.13±27.65 pg/mL vs 56.00±7.15 pg/mL, 68.02±15.03 pg/mL, respectively, P＜0.01). In addition, no obvious side effects in mice and no change in gastric inflammation were observed. CONCLUSION: The multiple oral immunizations with the attenuated S. typhimurium expressing H pylori UreB could induce significant systemic immune responses, suggesting it may be used as oral vaccine against H pylori infection.