Diepitopic construct of functionally and epitopically complementary peptides enhances immunogenicity, reactivity with glucosyltransferase, and protection from dental caries

Coimmunization with peptide constructs from catalytic (CAT) and glucan-bind ing (GLU) domains of glucosyltransferase (GTF) of mutans streptococci has r esulted in enhanced levels of antibody to the CAT construct and to GTF, We designed and synthesized a diepitopic construct (CAT-GLU) containing two co pies of both CAT (B epitope only) and GLU (B and T epitope) peptides, The i mmunogenicity of this diepitopic construct was compared with that of indivi dual CAT and GLU constructs by immunizing groups of Sprague-Dawley rats sub cutaneously in the salivary gland vicinity with the CAT-GLU, CAT, or GLU co nstruct or by treating rats by sham immunization. Levels of serum immunoglo bulin G (Igc) antibody to GTF or CAT in the CAT-GLU group were significantl y greater than in GLU- or CAT-immunized groups, Immunization with CAT-GLU w as compared to coimmunization with a mixture of CAT and GLU in a second rod ent experiment under a similar protocol, CAT-GLU immunization resulted in s erum IgG and salivary IgA responses to GTF and CAT which were greater than after coimmunization, Immunization with the diepitopic construct and commun ization with CAT and GLU constructs showed proliferation of T lymphocytes t o GTF, Immunization with either the CAT or GLU construct has been shown to elicit significant protection in a rodent dental caries model. Similarly in this study, the enhanced response to GTF after immunization with the CAT-G LU construct resulted in protective effects on dental caries. Therefore, th e CAT-GLU diepitopic construct can be a potentially important antigen for a caries vaccine, giving rise to greater immune response than after immuniza tion with CAT, GLU, or a mixture of the two.