ABSTRACT
AIM: To evaluate whether attenuated Salmonella typhimurium 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-UreB at a 3-wk interval. Twelve weeks after oral immunization of mice, serum IgG antibodies were evaluated by ELISA assay. Gamma interferon (IFN-gamma) and interleukin 10 (IL-10) in the supernatant 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 SL3261 control groups (A450, 0.373+/-0.100 vs 0.053+/-0.022, 0.142+/-0.039, respectively, P<0.01). Moreover, IFN-gamma 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-10 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.