Expression, Purification and Evaluation of Antigenicity of CagA Antigenic Fragment of Helicobacter pylori

Helicobacter pylori is a human pathogen that causes chronic gastritis, which playsrole in gastric and duodenal ulcers, is also involved in gastric carcinogenesis and may be regarded as a possible important factor in at least a subset of patients with functional dyspepsia.. This study was aimed to construct a recombinant protein containing H. pylori antigenic CagA region and determine its antigenicity as a vaccine candidate against H. pylori.. The antigenic region of CagA gene was detected by bioinformatics techniques. In this study, the H. pylori antigenic CagA region was amplified by PCR and sub-cloned to prokaryotic expression vector pET32a. Escherichia coli BL21 (DE3) pLysS was transformed with pET32a- CagA and gene expression was induced by IPTG. The expressed protein was purified by affinity chromatography using Ni-NTA resin. The integrity of the product was confirmed by western-blot analysis using Sera of infected individual. Finally antigenicity was studied by western-blot analysis using human sera infected with H. pylori.. Enzyme digestion analysis, PCR and sequencing showed that the target gene (1245 bp) was correctly inserted into the recombinant vector. The expressed protein was purified using affinity chromatography by Ni-NTA resin. The data also indicated that CagA protein from H. pylori detected from patients'' sera.. Results indicates that antigenic region of recombinant CagA protein were recognized as an antigen, so it might be a candidate for the development of H. pylori vaccine, ELISA kit designs and serological diagnosis of H. pylori infections..