Adherence of cariogenic streptococci to the smooth surfaces of teeth has been shown to lead to plaque formation and ultimately to caries production. This adherence can be reproduced in vitro and requires sucrose in the growth media. The work reported here describes the development of an assay based on the ability of immune rabbit serum to inhibit adherence of Streptococcus mutans 6715 to glass surfaces. Rabbits were immunized with Formalin-killed whole bacteria. Sera were titered for adherence inhibition and bacterial agglutination. The former assay was found to be dependent upon immunoglobulin G (IgG) antibody, whereas the latter detected either IgG or IgM antibodies. These two assays appeared to detect different antigens. It was hypothesized that the adherence inhibition assay detects antibody directed against an enzyme, perhaps dextransucrase, responsible for dextran synthesis, since immune serum was found to inhibit incorporation of radiolabel from 14Csucrose into cell wall extract. The adherence inhibition assay has potential application for study of other cariogenic bacteria. Studies are being pursued in the hope that this assay may lead to a means of control of dental caries.

Immunization of two cynomolugus and three rhesus monkeys with purified type II collagen resulted in the development of polyarthritis. Arthritis first became clinically apparent 7 wk after primary immunization and persisted for 16 mo. Radiologic examination of the limbs demonstrated soft tissue swelling with severe joint destruction including loss of cartilage and bone. Involved joints eventually became ankylosed with permanent loss of some motion. All of the monkeys developed a response to the immunizing collagen as determined by ELISA of serum for antibodies. Arthritis was associated with weight loss and constitutional symptoms, including lethargy and refusal to eat. One monkey became so debilitated that it was necessary to euthanize it. Histologic examination of the joints showed synovial hypertrophy with pannus formation. A control monkey immunized with type I collagen suffered no apparent ill effects.

Immune sera to strains of Streptococcus mutans were found to inhibit agglutination of bacterial suspensions to which either high-molecularweight dextran or sucrose was added. This inhibitory activity was shown to be mediated by antibody of the immunoglobulin G class. A semiquantitative assay was developed which demonstrated cross-inhibition of dextran/sucrose-induced agglutination among several strains of S. mutans. Antiserum to a partially purified glucosyltransferase was found to lack agglutination inhibition activity, consistent with the hypothesis that the dextran-binding antigen detected by the assay is immunologically distinct from the glucan-synthetic enzyme. A model for glucan synthesis and binding consistent with the reported data is described.Bacterial strains of Streptococcus mutans share the ability to synthesize high-molecularweight extracellular glucan polymers from sucrose through the synthetic action of cell-bound and cell-free glucosyltransferase enzymes (6, 8). Glucan production is closely associated with the ability of these bacteria to adhere to tooth surfaces as dental plaque (6).Some glucan-producing bacteria may be detected by observing their agglutination after the addition of sucrose (9) or dextran (7) to bacterial suspensions grown in the absence of sucrose.

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