Cloning and Expression of Recombinant Helicobacter pylori Urease A and B Subunits as a Putative Vaccine

Helicobacter pylori infection is among the most prevalent infections in the world involving more than half the adult population. H. pylori infection results in active chronic gastritis, peptic ulcers and enhances the risk of gastric malignancies. It is of utmost importance to prevent H. pylori infection particularly in highly prevalent countries including Iran. The urease holoenzyme produced by the entire Helicobacter species is essential for their virulence such that urease-negative mutant strains are unable to colonize the gastric lumen of various animal models. Furthermore, urease has shown to be an effective immunogen. Despite the fact that urease is considered among the very conserved genes of this pathogen, our molecular studies have shown that H. pylori strains obtained from Iranian patients vary considerably from those of other populations particularly the Western strains. Therefore, in order to develop a putative vaccine against H. pylori infection for the Iranian population, we have PCR-amplified and cloned the A and B subunits of this gene from a local H. pylori strain. Following identity confirmation, it was subcloned into a pET expression vector under the control of T7 promoter. The resulting plasmid was transformed into E. coli BL21-DE3 strain. Laboratory scale culture of the resulting transformants was analyzed by SDS-PAGE and Western blotting techniques. This analysis confirmed the expression of the A and B subunit of H. pylori urease protein up to 25% of the total cellular protein.