Background:Helicobacter pylori,a gram-negative bacterial pathogen that expresses a strong urease activity,is associated with the development of gastroduodenal disease.Urease B subunit,one of the two structural subunits of urease,was expressed in E coll BL21(DE3) strain.The objective of this study was to evaluate the effects of Helicobacter pylori urease B subunit on the immune responses in mice by subcutaneous immunization.Methods:The mice were immunized and boosted with Helicobacter pylori urease B subunit antigen subcutaneously three times with 2-wk intervals between the immunizations and boosters.The mice in the control group were immunized with PBS.The adjuvant group received PBS containing complete/incomplete freund’s adjuvant identical to antigen group without Helicobacter pylori urease B subunit antigen.Four weeks after the final booster,all the mice were sacrificed.Blood was collected on d 0,14,28 and 56 before immunization,booster and sacrifice,respectively.Immediately after sacrifice,gastric liquid and spleen were collected for antibody and cytokine analyses.Results:Urease B subunit increased the concentrations of serum and gastric anti-urease B antigen specific IgG,and the levels of interleukin-4 and interferon-γ in splenocytes of the mice(P< 0.05).Conclusions:This study demonstrated that recombinant urease B subunit can induce systemic and local immune responses in mice by subcutaneous immunization,which might be used as the effective component of vaccine aaainst Helicobacter ovlori. Background: Helicobacter pylori, a gram-negative bacterial pathogen that expresses a strong urease activity, is associated with the development of gastroduodenal disease. Urease B subunit, one of the two structural subunits of urease, was expressed in E coll BL21 (DE3) strain The objective of this study was to evaluate the effects of Helicobacter pylori urease B subunit on the immune responses in mice by subcutaneous immunization. Methods: The mice were immunized and boosted with Helicobacter pylori urease B subunit antigen subcutaneously three times with 2-wk intervals between the immunizations and boosters.The mice in the control group were immunized with PBS. The adjuvant group received PBS containing complete / incomplete freund’s adjuvant identical to antigen group without Helicobacter pylori urease B subunit antigen. Four weeks after the final booster, all the mice were sacrificed. Blood was collected on d 0,14,28 and 56 before immunization, booster and sacrifice, respectively. Immediately after s acrifice, gastric liquid and spleen were collected for antibody and cytokine analyzes. Results: Urease B subunit increased the concentrations of serum and gastric anti-urease B antigen specific IgG, and the levels of interleukin-4 and interferon-γ in splenocytes of the mice (P <0.05) .Conclusions: This study demonstrated that recombinant urease B subunit can induce systemic and local immune responses in mice by subcutaneous immunization, which might be used as the effective component of vaccine aaerobic Helicobacter ovlori.