The purpose of this project is to isolate selectively the surface components of Streptococcus sanguis cells FW213, and begin the biochemical and physical analyses of one of these components - pili. Pili were chosen to investigate first as a large body of evidence is accumulating to suggest these structures are organelles of adhesion in other bacteria. The significance of these pili in adhesion to saliva-coated hydroxyapatite will be studied using whole piliated cells and purified cells and purified pili. A survey of the percentage of piliated S. sanguis strains in dental plaque will be conducted. The feasibility of pursuing studies of a vaccine using pili will be determined on the degree of serological homogeneity or cross-reactivity of pili found on commensal S. sanguis cells. The metabolic requirements for pili outgrowth and the environmental factors that influence pili expression will be investigated.