AIM:To clone flagellin genes A(flaA)and B(flaB)from aclinical strain of Helicobacter pylori(H pylori)and to constructprokaryotic expression systems of the genes and identifyimmunity of the fusion proteins.METHODS:The flaA and flaB genes from a clinical H pyloriisolate Y06 were amplified by high fidelity PCR.Thenucleotide sequences of target DNA amplification fragmentsfrom the two genes were sequenced after T-A cloning.Therecombinant expression vector pET32a inserted with flaAand flaB genes was constructed,respectively.Theexpressions of FlaA and FlaB fusion proteins in E.coliBL21DE3 induced by isopropylthio-β-D-galactoside(IPTG)at different concentrations were examined by SDS-PAGE.Western blot using commercial antibodies against whole cellof H pylori and immunodiffusion assay using self-preparedrabbit antiserum against FlaA(rFlaA)or FlaB(rFlaB)recombinant proteins were applied to the determination ofthe fusion proteins immunity.ELISA was used to detect theantibodies against rFlaA and rFlaB in sera of 125 H pyloriinfected patients and to examine rFlaA and rFlaB expressionin 98 clinical isolates of H pylori,respectively.RESULTS:In comparison with the reported correspondingsequences,the nucleotide sequence homologies of thecloned flaA and flaB genes were from 96.28-97.13 % and96.31-97.73 %,and their putative amino acid sequencehomologies were 99.61-99.80 % and 99.41-100 % for thetwo genes,respectively.The output of rFlaA and rFlaBexpressed by pET32a-flaA-BL21DE3 and pET32a-flaB-BL21DE3 systems was as high as 40-50 % of the totalbacterial proteins.Both rFlaA and rFlaB were able tocombine with the commercial antibodies against whole cellof H pylori and to induce rabbits to produce specificantibodies with the same 1:2 immunodiffusion titers afterthe animals were immunized with the two recombinant proteins.Ninety-eight and zero point 4 and 92.80 % of theserum samples from 125 patients infected with H pyloriwere positive for rFlaA and rFlaB antibodies,respectively.One hundred percent and 98.98 % of the 98 tested isolatesof H pylori were detectable for rFlaA and rFlaB epitopes,respectively.CONCLUSION:Two prokaryotic expression systems withhigh efficiency of H pylori flaA and flaB genes weresuccessfully established.The expressed rFlaA and rFlaBshowed satisfactory immunoreactivity and antigenicity.Highfrequencies of FlaA and FlaB expression in different H pyloriclinical strains and the general existence of specific antibodiesagainst FlaA and FlaB in H pylori infected patients stronglyindicate that FlaA and FlaB are excellent antigen candidatesfor developing H pylori vaccine. AIM: To clone flagellin genes A (flaA) and B (flaB) from aclinical strain of Helicobacter pylori (H pylori) and to construct prokaryotic expression systems of the genes and identify immunity of the fusion proteins. METHODS: The flaA and flaB genes from a clinical H pylori isolate Y06 were amplified by high fidelity PCR. The nucleotide sequences of the target DNA amplification fragments from the two genes were sequenced after TA cloning. Both recombinant expression vectors pET32a inserted with flaA and flaB genes were constructed, respectively. Theexpressions of FlaA and FlaB fusion proteins in E. coli BL21DE3 induced by isopropylthio-β-D-galactoside (IPTG) at different concentrations were examined by SDS-PAGE. Western blot using commercial antibodies against whole cell of H pylori and immunodiffusion assay using self-preparedrabbit antiserum against FlaA (rFlaA) or FlaB ) recombinant proteins were applied to the determination of the fusion proteins immunity. ELISA was used to detect the antibodies against rFlaA and r FlaB in sera of 125 H pylori infected patients and to examine rFlaA and rFlaB expression in 98 clinical isolates of H pylori, respectively .RESULTS: In comparison with the corresponding sequences published, the nucleotide sequence homologies of the cloned flaA and flaB genes were from 96.28-97.13% and96 .31-97.73%, and their putative amino acid sequenceologies were 99.61-99.80% and 99.41-100% for thetwo genes, respectively. The output of rFlaA and rFlaBexpressed by pET32a-flaA-BL21DE3 and pET32a-flaB-BL21DE3 systems was as high as 40-50% of the total bacterial material. Bt rFlaA and rFlaB were able tocombine with the commercial antibodies against whole cell of H pylori and to induce rabbits to produce specific antibodies with the same 1: 2 immunodiffusion titers afterthe animals were immunized with the two recombinant proteins . Ninety-eight and zero point 4 and 92.80% of the samples from 125 patients infected with H pyloriwere positive for rFlaA and rFlaB antibodies, respectively. One Hundred percent and 98.98% of the 98 tested isolates of H pylori were detectable for rFlaA and rFlaB epitopes, respectively.CONCLUSION: Two prokaryotic expression systems with high efficiency of H pylori flaA and flaB genes weresuccessfully established.The expression rFlaA and rFlaBshowed satisfactory immunoreactivity and antigenicity. High Frequencies of FlaA and FlaB expression in different H pyloriclinical strains and the general existence of specific antibodies against FlaA and FlaB in H pylori infected patients stronglyindicate that FlaA and FlaB are excellent antigen candidates for developing H pylori vaccine.