The overall goal of this research project is to determine the role of salivary glycoproteins in the attachment of oral bacteria to the mucosal surfaces of the oral cavity. To pursue these studies logically, the experiments proposed in this application are focused on the mechanisms of adhesion of Actinomyces naeslundii to the buccal epithelial cells, and the role of salivary macromolecules play in mediating these ligand-receptor interactions. Towards that goal specific efforts will be directed toward: (1) isolating and characterizing the salivary components that adsorb to the surface of A. naeslundii from human saliva (actinomyces agglutinin) and mediates and adherence of this bacterial to buccal epithelial cells, (2) studying the specific binding characteristics of the actinomyces-bound salivary macromolecule(s) to cells of A. naeslundii and to surfaces of buccal epithelial cells, (3) examining the buccal cells for content and distribution of the agglutinin bound to their surfaces naturally and after experimental treatment, and (4) determining the major functional domain of actinomyces-agglutinin that mediates the binding of the intact molecule to A. naeslundii and to buccal epithelial cells. To achieve these goals, lactose-sensitive-fimbriae mediated attachment of A. naeslundii to buccal epithelial cells will be employed as a parameter of bacteria-epithelial cell interactions. The salivary macromolecules that were adsorbed to the surfaces of A. naeslundii will be eluted and purified to homogeneity. The actinomyces-agglutinin will be investigated for their role in mediating adherence of A. naeslundii to epithelial cells. Radiolabeled agglutinin will be examined in assays of the binding of the agglutinin to bacteria and epithelial cells. Binding studies will be performed to determine the specificity, affinity and number of agglutinin binding sites on bacteria and epithelial cells. Several different chemical and enzymatic treatments will be used to measure agglutinin levels in saliva and on epithelial cells. The proposed studies should provide valuable information necessary to understand the role of salivary components in bacterial adhesion. It may also prove useful in the development of a receptor-vaccine to prevent bacterial colonization of susceptible mucosal surfaces.