Construction of an attenuated Salmonella typhimurium vaccine carrying the Helicobacter pylori hpaA gene

Abstract

OBJECTIVE: Helicobacter pylori is documented to have infected more than half of the world’s population. It colonizes the human stomach and is associated with the development of chronic active gastritis, peptic ulcer disease, gastric adenocarcinoma and gastric mucosa-associated lymphoid tissue (MALT) lymphoma. Immunization against this bacterium represents a cost-effective strategy to reduce global gastric cancer rates and would have a major impact on H. pylori-related peptic ulcer disease. HpaA, a subunit protein of H. pylori adhesin, is known to be the pathogenic factor and attenuated Salmonella typhimurium is a live vaccine vector. The present study aimed at constructing and identifying a live attenuated S. typhimurium vaccine carrying the hpaA gene of H. pylori. METHODS: The hpaA gene was amplified from H. pylori genomic DNA by polymerase chain reaction (PCR) and cloned into the NcoI-SalI site of the prokaryotic expression plasmid pTrc99A. After sequence analysis of the hpaA gene, the identified recombinant plasmid was then used to transform a live attenuated S. typhimurium, namely SL3261, and positive clones were screened by PCR and restriction enzyme digestion. RESULTS: Confirmed by PCR, restriction enzyme digestion and sequence analysis, a recombinant prokaryotic expression plasmid, namely pTrc99A-hpaA, harboring approximately 560 bp hpaA was constructed and the recombinant plasmid was then successfully introduced into a live attenuated S. typhimurium SL3261. CONCLUSION: A recombinant live attenuated S. typhimurium vaccine harboring the H. pylori hpaA gene was constructed and identified. This work will help develop an oral recombinant live vaccine against H. pylori infection.