THIS IS A SHANNON AWARD PROVIDING PARTIAL SUPPORT FOR THE RESEARCH PROJECTS THAT FALL SHORT OF THE ASSIGNED INSTITUTE'S FUNDING RANGE BUT ARE IN THE MARGIN OF EXCELLENCE. THE SHANNON AWARD IS INTENDED TO PROVIDE SUPPORT TO TEST THE FEASIBILITY OF THE APPROACH; DEVELOP FURTHER TESTS AND REFINE RESEARCH TECHNIQUES; PERFORM SECONDARY ANALYSIS OF AVAILABLE DATA SETS; OR CONDUCT DISCRETE PROJECTS THAT CAN DEMONSTRATE THE PI'S RESEARCH CAPABILITIES OR LEAD ADDITIONAL WEIGHT TO AN ALREADY MERITORIOUS APPLICATION. THE APPLICATION BELOW IS TAKEN FROM THE ORIGINAL DOCUMENT SUBMITTED BY THE PRINCIPAL INVESTIGATOR. A prerequisite for the successful colonization of many bacteria within the oral cavity is their ability to adhere to hard and soft tissue surfaces of the host, as well as to other species of bacteria. One of the factors that may allow Prevotella intermedia, a Gram-negative black- pigmenting anaerobic bacterium which is thought to be associated with certain types of periodontal disease, to colonize and emerge as a pathogen is its capability for specific attachment to other subgingival bacteria. Studies of the surface molecules of P. intermedia mediating these adherent interactions are few. Consequently there is a need to elucidate the mechanisms by which this bacterium binds to other microorganisms at the molecular level. From the results of our previous work we were able to demonstrate that one strain, P. intermedia 27, was capable of specific coaggregation with selected strains of Actinomyces naesundii by an apparent lectin-like carbohydrate type mechanism with the Prevotella strain possessing the proteinaceous adhesin(s) molecules on its surface. Recently, isolation of coaggregation-defective mutants of P. intermedia 27 that are specific for two of the seven P. intermedia-A. naeslundii coaggregation reactions that were examined, suggested that more than one type of adhesin-receptor interaction may be involved in the interaction of this P. intermedia strain with A. naeslundii. Isolated outer membrane preparations from the parent, but not from the mutants were capable of inhibiting these two coaggregation reactions. The long-term goals are: (1) to determine the co-adherence mechanism(s) of P. intermedia to A. naeslundii strains and (2) to confirm the function of the adhesive component(s) by generating and testing isogeneic mutants lacking the adhesive component(s) for virulence in an appropriate animal model. The specific aims will be: (l) to isolate and characterize the P. intermedia outer membrane-associated adhesive component(s) which mediates its interaction with Actinomyces; determine the biochemical and physical characteristics of the adhesin; (2) determine the functional domain(s) and characterize the adherent properties of the adhesin using monoclonal antibodies; and (3) to clone the gene(s) which code for the adhesin; characterize the gene(s) and recombinant adhesin. The biochemical and molecular information obtained from these studies should contribute to a more complete understanding of the virulence factors which allow P. intermedia to colonize the oral cavity.