Cloning and expression of gene encoding Helicobacter pylori outer membrane protein with M r 26 000

Aim To construct a recombinant vector containing gene encoding Helicobacter pylori ( Hp ) outer membrane protein(OMP) with M r 26 000 and express in E.coli BL21. Methods The target gene was amplified from Hp chromosome by PCR, and then was inserted into the prokaryotic expression vector pET32a(+). The recombinant vector was used to transform and was expressed in E.coli BL21(DE3). Results Enzyme digestion analysis and sequencing showed that the target gene had been inserted into recombinant vector. Compared with sequence reported by Tomb et al , there was 1.1 % of base mutation and 1.51% of amino acid mutation in cloned OMP. SDS PAGE analysis showed that relative molecule mass ( M r) of expressed product was 46 ×10 3 , and soluble expression product accounted for 38.96% of total bacterial protein. After purification with Ni NTA agarose resin, the purity of recombinant fusion protein was about 95%. The ELISA result showed that recombinant fusion protein could be recognized by anti Hp serum, suggesting that this protein have good antigenicity. Conclusion The gene coding for Hp OMP is cloned and expressed successfully. These results lay the foundation for research on development of Hp protein vaccine and a quick diagnostic kit of Hp infection.