A truncated form of HpaA is a promising antigen for use in a vaccine against Helicobacter pylori

HpaA is a Helicobacter pylori-specific lipoprotein that has been shown to be an effective protective antigen for mucosal vaccination against H. pylori infection in mice. However, detergents are needed for the purification of full-length HpaA (HpaAfull), which might confer toxicity, thus making HpaAfull unsuitable for use in a human vaccine. We here describe a recombinantly produced truncated version of HpaA (HpaAtrunc), which is easily purified without the use of detergents. Evaluation in the murine H. pylori infection model showed that sublingual immunization with HpaAtrunc was equally immunogenic and protective as immunization with HpaAfull. Immunization with a combination of HpaAtrunc and recombinant UreB protein induced strong immune responses to both antigens and importantly had a strong synergistic effect on protection, associated with synergistically increased expression of IL-17 in the stomach. Notably, sublingual immunization with HpaAtrunc and UreB was superior to corresponding intragastric immunization with regard to the level of protection induced. In conclusion, HpaAtrunc is a promising, readily produced, non-toxic recombinant antigen for inclusion in a mucosal vaccine against H. pylori infection, which may preferably be given sublingually together with UreB.