A Fusion Protein of the Hemagglutinin A Antigenic Region of Porphyromonas gingivalis and Maltose-Binding Protein Induces Antibody Responses in the Oral Cavity

Abstract

Maltose-binding protein (MBP) produced by Escherichia coli acts as an adjuvant when fused to various antigens. In this study, the antigenic region of hemagglutinin A of Porphyromonas gingivalis with a molecular mass of 25 kDa (25k-hagA) was fused to MBP (25k-hagA-MBP) and the efficacy of the resulting fusion protein as a nasal vaccine was assessed. While nasal immunization with 25k-hagA induced no antibody responses, 25k-hagA-MBP elicited high serum IgG, IgA, and secretory IgA anti-25k-hagA antibodies in the saliva. When 25k-hagA-MBP was co-administered with an established mucosal adjuvant, cholera toxin, 25k-hagA-specific serum IgG and salivary IgA antibody responses were not further elevated. Interestingly, 25k-hagA mixed with MBP failed to induce 25k-hagA-specific antibody responses. These findings suggest that MBP must be fused to the target antigen for induction of antigen-specific antibody responses and that nasal administration of 25k-hagA-MBP may be an effective mucosal vaccine for the prevention of P. gingivalis infection.