Antigenicity Identification of a Novel Recombinant Multi-Epitope Antigen Based on FlaA and UreB Antigens of Helicobacter pylori

Helicobacter pylori is the main cause of stomach ulcers and gastric cancer. Hence, the diagnosis, treatment, and prevention of H. pylori infection can considerably reduce the fatality. This study aimed to construct a dual-antigen protein by combining the antigenic regions of UreB and FlaA of H. pylori and determine its antigenicity as a promising vaccine and serodiagnosis candidate. The antigenic regions of FlaA and UreB were detected by immunological bioinformatics, amplified and joined together by polymerase chain reaction (PCR) with special primers containing linker sequences. Then, it was cloned into pET-32a and after expression and purification of the recombinant multi-epitope protein (rFlaA-UreB), its antigenicity was evaluated by immunoblotting using the sera of infected patients. DNA sequencing and enzyme digestion analysis showed the rFlaA-UreB gene was successfully inserted into pET32a. The recombinant protein was produced and purified via affinity chromatography and its molecular weight was similar to what had been predicted. Moreover, data indicated that rFlaA-UreB was recognized by all patients’ sera and its sensitivity and specificity were high. Although the developed recombinant multi-epitope protein was very smaller and lighter than the natural forms of these two critical antigens, they all had close antigenic properties. Therefore, this recombinant protein can be an important antigen in the diagnosis and vaccination against H. pylori.