Abstract： Objective To construct a recombinant live attenuated Salmonella typhimurium vaccine strain expressing Helicobacter pylori urease subunit B (ureB).Methods ureB gene was amplified by PCR and cloned into a prokaryotic expression plasmid pTrc99a, and the identified recombinant plasmid was then used to transform an attenuated Salmonella typhimurium vaccine strain SL3261. The ureB expressed in the recombinant vaccine strain was analyzed by SDS-PAGE and optical density scanning. Two and 10 days after recombinant strain intragastric immunization, the C57BL/6 mice were sacrificed, and the spleens and terminal ileums were cultured.Results The ureB gene could be amplified from the recombinant prokaryotic expression plasmid pTrc99A-ureB and the plasmids extracted from transformed SL3261 strain. SDS-PAGE and optical density scanning indicated that ureB was expressed in the recombinant vaccine strain SL3261 (pTrc99A-ureB) as a protein with 66*!kD of molecular weight. Recombinant strain was found in both spleen an terminal ileum of each mouse two and ten days after intragastric immunization.Conclusions A recombinant liver attenuated Salmonella typhimurium vaccine strain expressing Helicobacter pylori ureB was constructed and identified, and this study will help to develop an oral recombinant live vaccine against Helicobacter pylori infection.