IMMUNIZATION OF RATS WITH SYNTHETIC PEPTIDE CONSTRUCTS FROM THE GLUCAN-BINDING OR CATALYTIC REGION OF MUTANS STREPTOCOCCAL GLUCOSYLTRANSFERASE PROTECTS AGAINST DENTAL-CARIES

Previously, we have described peptide constructs from two regions of g lucosyltransferase (GTF) of mutans streptococci. A putative catalytic site in the amino-terminal half of the molecule and a repeated glucan- binding site in the carboxyl-terminal half of GTF were the regions upo n which sequences were based. The present study explored the effects o f immunization with these peptide constructs (called CAT or GLU) and w ith streptococcal GTFs from Streptococcus sobrinus and S. mutans on im munological, microbiological, and disease parameters, Groups of immuni zed Sprague-Dawley rats were infected with either 10(8) S. sobrinus 67 15 or 10(8) S. mutans SJ32 organisms. Serum immunoglobulin G antibody levels, determined by enzyme-linked immunosorbent assay, to the respec tive peptide constructs and to the appropriate streptococcal GTP were significantly increased (after immunization) prior to infection and at the end of the experiment. Also, serum antibody from CAT-, GLU-, and S. sobrinus GTF-immunized rats inhibited S. sobrinus GTF-mediated inso luble glucan synthesis (all) and S. mutans GTF-mediated soluble glucan synthesis (all except anti-GLU) from sucrose. Immunization with the C AT or GLU peptide construct resulted in significantly reduced smooth s urface and sulcal caries after infection with S. sobrinus. Sulcal dent al caries after infection with S. mutans SJ32 were also significantly reduced in CAT- and GLU-immunized rats. Thus, immunization with peptid es whose sequences are based on putative functional domains of mutans streptococcal GTF are protective toward a cariogenic S. sobrinus or S. mutans infection.