The ELISA system for measuring antibody reactive to Fusobacterium nucleatum in the sera of patients with chronic periodontitis.

Humoral IgG, IgA and IgM responses to three typed oral strains of F. nucleatum were examined in patients with chronic periodontitis and in individuals with clinically healthy gingiva. Attempts were made to isolate F. nucleatum from either the pathologic gingival crevices or healthy sulci in this study. Higher levels of IgG and IgA reactive to all three strains were observed in the chronic periodontitis patients; however, there were no differences between the IgM levels in the diseased and healthy individuals. Immunodiffusion studies with rabbit antiserum and adsorption studies of the human sera demonstrated a sharing of antigenic determinants by the F. nucleatum strains. F. nucleatum strains were isolated from 14 of the 15 individuals in the study.