AIM:To clone ureB gene from a clinical isolate ofHelicobacter pylori and construct a prokaryotic expressionsystem of the gene and identify immunity of the expressedrecombinant protein.METHODS:ureB gene from a clinical H pylori strain Y06was amplified by the high fidelity polymerase chain reactiontechnique.The target DNA fragment amplified from ureBgene was sequenced after T-A cloning.Prokaryoticrecombinant expression vector pET32a inserted with ureBgene (pET32a-ureB) was constructed.The expression ofrecombinant UreB protein (rUreB) in E.coli BL21DE3induced by isopropylthio-β-D-galactoside (IPTG) at differentconcentrations was examined by SDS-PAGE.Western blotusing commercial antibodies against whole cell of H pyloriand an immunodiffusion assay using a self-prepared rabbitanti-rUreB antibody were applied to determine immunityof the target recombinant protein.ELISA was used to detectthe antibody against rUreB in sera of 125 H pylori infectedpatients and to examine rUreB expression in 109 H pyloriisolates.RESULTS:In comparison with the reported correspondingsequences,the nucleotide sequence homology of the clonedureB gene was from 96.88-97.82% while the homology of itsputative amino acid sequence was as high as 99.65-99.82%.The rUreB output expressed by pET32a-ureB-BL21DE3 wasapproximate 30% of the total bacterial proteins,rUreBspecifically combined with the commercial antibodiesagainst whole cell of H pylori and strongly induced rabbitsto produce antibody with a 1:8 immunodiffusion titer afterthe animals were immunized with the recombinant protein.Serum samples from all H pylori infected patients werepositive for UreB antibody and UreB expression weredetectable in all tested H pylori isolates.CONCLUSION:A prokaryotic expression system with highexpression efficiency of H pylori ureB gene was successfullyestablished.The expressed rUreB showed qualifiedimmunoreactivity and antigenicity.High frequencies of UreB expression in different Hpyloriisolates and specific antibodyagainst UreB in sera of H pylori infected patients indicatethat UreB is an excellent antigen candidate for developingH pylori vaccine. AIM: To clone ureB gene from a clinical isolate of Helicobacter pylori and construct a prokaryotic expression system of the gene and identify immunity of the expressed recombinant protein. METHODS: ureB gene from a clinical H pylori strain Y06 was amplified by the high fidelity polymerase chain reaction technique. The target DNA fragment amplified from ureB gene was sequenced after TA cloning. Prokaryotic expression vector pET32a inserted with ureB gene (pET32a-ureB) was constructed. The expression of recombinant UT protein (rUreB) in E. coli BL21DE3 induced by isopropylthio-β-D-galactoside at different protocols were was examined by SDS-PAGE. Western blotusing commercial antibodies against whole cell of H pyloriand an immunodiffusion assay using a self-prepared rabbit anti-rUreB antibody were applied to determine immunity of the target recombinant protein. ELISA was used to detect the antibody against rUreB in sera of 125 H pylori infected patients and to examine rUreB expression in 10 9 H pylori isolates .RESULTS: In comparison with the corresponding sequences sequenced, the nucleotide sequence homology of the clonedureB gene was from 96.88-97.82% while the homology of itsputative amino acid sequence was as high as 99.65-99.82%. The rUreB output expressed by pET32a -ureB-BL21DE3 wasapproximate 30% of the total bacterial proteins, rUreBspecifically combined with the commercial antibodies whole cell of H pylori and strongly induced rabbit starter produce antibodies with a 1: 8 immunodiffusion titer afterthe animals were immunized with the recombinant protein. Serum samples from all H pylori infected patients were positive for UreB antibody and UreB expression were detectable in all tested H pylori isolates. CONCLUSION: A prokaryotic expression system with highexpression efficiency of H pylori ureB gene was successfully established. The expressed rUreB showed qualified immunoreactivity and antigenicity. High frequencies of UreB expression in different Hpyloriisolates and specific antibodyagainst UreB in sera of H pylori infected patients indicate that UreB is an excellent antigen candidate for developing H pylori vaccine.