Immunological Response to Parenteral Vaccination with Recombinant Hepatitis B Virus Surface Antigen Virus-Like Particles Expressing Helicobacter pylori KatA Epitopes in a Murine H. pylori Challenge Model

Abstract

Virus-like particles (VLPs) based on the small envelope protein of hepatitis B virus (HBsAg-S) are immunogenic at the B- and T-cell level. In this study, we inserted overlapping sequences encoding the carboxy terminus of the Helicobacter pylori katA gene product into HBsAg-S. The HBsAg-S-KatA fusion proteins were able to assemble into secretion-competent VLPs (VLP-KatA). The VLP-KatA proteins were able to induce KatA-specific antibodies in immunized mice. The mean total IgG antibody titers 41 days post-primary immunization with VLP-KatA (2.3 נ103) were significantly greater (P < 0.05) than those observed for vaccination with VLP alone (5.2 נ102). Measurement of IgG isotypes revealed responses to both IgG1 and IgG2a (mean titers, 9.0 נ104 and 2.6 נ104, respectively), with the IgG2a response to vaccination with VLP-KatA being significantly higher than that for mice immunized with KatA alone (P < 0.05). Following challenge of mice with H. pylori, a significantly reduced bacterial load in the gastric mucosa was observed (P < 0.05). This is the first report describing the use of VLPs as a delivery vehicle for H. pylori antigens.