The purpose of this proposal is to develop a rapid, sensitive and reproducible spectrophotometric technique for the quantitation of antibody in serum and saliva directed against cell surface antigens of Actinomyces naeslundii and Actinomyces viscosus. In light of the possible importance of cell surface components in the pathogenesis of periodontal disease and in the taxonomic classification of Actinomyces, the cell surface antigens to which antibody is directed will be analyzed. To carry out these objectives rabbits will be immunized with formalin-killed whole cells. Antibody will be isolated from immune serum and saliva using whole cells as an immunoadsorbant. Antibody will be reacted with whole cells and the reaction followed in a spectrophotometer. The relationship between antibody concentration and change in optical density will be determined for quantitation of antibody in solution. The cell surface antigens which take part in the observed reactions will be extracted from whole cells, isolated and purified by gel filtration and ion-exchange chromatography and immunochemically analyzed.