The Experimental Study On Bivalence Genetic Engineering Fusion Vaccine Of Helicobacter Pylori Outer Membrane Protein

Objective:Helicobacter pylori is a gram-negative bacterium that resides in the mucosa of the human stomach.It has been generally accepted that colonization of the stomach by H.pylori is associated with the risk of different gastroduodenal diseases including chronic gastritis,peptic ulcer,gastric cancer,and mucosas asociatied lymphoid tissue lymphoma. Although the current recommended treatment regimens(bismuth salts or proton pump inhibitor in combination with two antibiotics) are effective, the high cost of medication and increasing occurrence of antibiotic-resistant strains hamper the efficacy of chemotherapeutic agents. An alternative approach is to develop a vaccine which would not only clear the organism, but also protect man against reinfection. In fact, the research workers in the medicine field throughout the world have put their research focus on H. pylori vaccine development.One of the key work of vaccine developing is to screen for the effective vaccine candidate proteins. At present, various approaches have been followed in the development of vaccines against H. pylori, most of which based on the use of selected antigens known to be involved in the pathogenesis of the infection, such as urease, the vacuolating cytotoxin(VacA), heat shock proteins(Hsp), the cytotoxin-associated antigen(CagA), neutrophil-activating protein(Nap). Outer membrane proteins of gram-negative bacteria had been proved to be of high immunocompetence to induce strong specific immunoreaction. As the targets for attacking of the immunocytes and antibodies, they can mediate immunoreaction to kill the bacteria more directly, and play an important role in immune protection. Lpp20 and AhpC are outer membrane protein of H.pylori, The encoding gene show highly conservative. But none of the antigens was capable of inducing protective immune response as strong as expected.