Cloning, Expression And Immunogenicity Analysis Of NapA Of Helicobacter Pylori

Helicobacter pylori is a Gram-negative microaerophilic bacillus that infects thestomachs of more than half of the global population. It has been confirmed thatH. pylori is the main cause of chronic gastritis and peptic ulcer disease, and has a closerelation to gastric mucosa-associated lymphoid tissue(MALT) lymphoma and gastricadenocarcinoma. The World Health Organization defined it as a class 1 carcinogen.Vaccine will be an effective and economic approach to prevent infection diseases ofmass population.H. pylori neutropphil-activating protein (HP-NAP) is localized in the bacterialcytosol and is released upon autolysis. It can bind to the external surface of the outermembrane and mediate the binding of H. pylori to the cell surface. NAP has also beenshown to be chemotactic for neutrophils and monocytes, which contribute to H.pylori-induced gastritis. It is able to bind and even condense DNA at slightly acid pHvalues to protect DNA against damage. NAP is a virulence facter important for thesurvival, colonization and inflammation of H. pylori.napA was amplified by PCR from genomic DNA of H. pylori strain 26695 andrecombinant plasmids pET28a-nap was constructed. The analysis of DNA sequenceshowed that the sequence of napA was the same as that published by GenBank.Taking 40% of total protein, fusion protein was expression in E. coli. The fusionprotein was purified by Chelating Fast Flow affinity chromatograpy followed bySephcryl S-200 gel filter chromatography. The purity of fusion was above 95%.Anti-NAP IgG titers in the serum of mice were significantly greater when NAP wasadministered with CpG ODN or/and LTB than NAP was delivered alone. Oralimmunization with NAP combined adjuvants can induce effective immune response.The fusion protein NAP can be taken as a potent antigen for Helicobacter pylori oralvaccine.We have obtained fusion protein of NAP with high purity, the immunogenicity ofNAP has been evaluated. These results would be helpful for the development of genetic engineering vaccine against H. pylori.