Antibody Production and Th1-biased Response Induced by an Epitope Vaccine Composed of Cholera Toxin B Unit and Helicobacter pylori Lpp20 Epitopes.

BACKGROUND

The epitope vaccine is an attractive potential for prophylactic and therapeutic vaccination against Helicobacter pylori (H. pylori) infection. Lpp20 is one of major protective antigens which trigger immune response after H. pylori invades host and has been considered as an excellent vaccine candidate for the control of H. pylori infection. In our previous study, one B-cell epitope and two CD4(+) T-cell epitopes of Lpp20 were identified.

OBJECTIVE

In this study, an epitope vaccine composed of mucosal adjuvant cholera toxin B subunit (CTB) and these three identified Lpp20 epitopes were constructed to investigate the efficacy of this epitope vaccine in mice.

METHODS

The epitope vaccine including CTB, one B-cell, and two CD4(+) T-cell epitopes of Lpp20 was constructed and named CTB-Lpp20, which was then expressed in Escherichia coli and used for intraperitoneal immunization in BALB/c mice. The immunogenicity, specificity, and ability to induce antibodies against Lpp20 and cytokine secretion were evaluated. After that, CTB-Lpp20 was intragastrically immunized to investigate the prophylactic and therapeutic efficacy in infected mice.

RESULTS

The results indicated that the epitope vaccine CTB-Lpp20 possessed good immunogenicity and immunoreactivity and could elicit specific high level of antibodies against Lpp20 and the cytokine of IFN-γ and IL-17. Additionally, CTB-Lpp20 significantly decreased H. pylori colonization in H. pylori challenging mice, and the protection was correlated with IgG, IgA, and sIgA antibody and Th1-type cytokines.

CONCLUSION

This study will be better for understanding the protective immunity of epitope vaccine, and CTB-Lpp20 may be an alternative strategy for combating H. pylori invasion.