Heterologous Prime-Boost Oral Immunization with GK-1 Peptide from Taenia crassiceps Cysticerci Induces Protective Immunity

Abstract

ABSTRACTOral immunization is a goal in vaccine development, particularly for pathogens that enter the host through the mucosal system. This study was designed to explore the immunogenic properties of theTaenia crassicepsprotective peptide GK-1 administered orally. Mice were orally immunized with the synthetic GK-1 peptide in its linear form with or without theBrucellalumazine synthase (BLS) protein adjuvant or as a chimera recombinantly bound to BLS (BLS-GK-1). Mice were boosted twice with GK-1 only at 15-day intervals. A significant rate of protection of 64.7% was achieved in GK-1-immunized mice, and that rate significantly increased to 91.8 and 96% when mice were primed with GK-1 coadministered with BLS as an adjuvant and BLS as a carrier, respectively. Specific antibodies and T cell activation and proliferation accompanied the protection induced, revealing the potent immunogenicity of GK-1. Through immunohistochemical studies, GK-1 was detected in T and B cell zones of the Peyer's patches (PP) and mesenteric lymph nodes. In the latter, abundant proliferating cells were detected by 5′-bromo-2′-deoxyuridine incorporation. No proliferation was detected in PP. Altogether, these results portray the potent immunogenic properties of GK-1 administered orally and reinforce the usefulness of BLS as an adjuvant and adequate vaccine delivery system for oral vaccines.