[Clone, expression and immunoreaction of napA gene of Helicobacter pylori].

AIM: To construct a prokaryotic expression system of Helicobacter pylori(Hp) (neutrophil-activating protein) napA gene, analyze nucleic acid sequence and study its immunity and inflammation. METHODS: napA fragment was amplified from Hp NCTC11639 chromosomal DNA by PCR. Its T-A was cloned, sequenced and compared with other Hp strains on the GenBank. Then the gene was cloned into pGEX-4T-1 fusion expression vector, expressed in E.coli and purified by GST-affinity chromatography. The purified product was used to screen 29 stains of mouse anti Hp monoclonal antibodies(mAb) and its immunity and inflammation analyzed with sera of Hp-infected patients by Western blot. RESULTS: napA fragment was composed of 435 base pairs (GenBank No.DQ341279) and the nucleotide homology with other Hp strains on the GenBank was 94%-98%. The molecular weight of the recombinant napA-pGEX-4T-1 expressed in E.coli was 44 kDa. 3 of 29 anti-Hp mAbs were against NAP. Western blot analysis proved that the recombinant NAP was specifically recognized by the sera of Hp-infected patients. CONCLUSION: The recombinant NAP has original immunoreaction. It is of great value to clinical sero-diagnosis and vaccine study of Hp.