SERODIAGNOSIS OF PORPHYROMONAS-GINGIVALIS INFECTION BY IMMUNOBLOT ANALYSIS WITH RECOMBINANT COLLAGENASE

The Porphyromonas gingivalis collagenase-specific serum immunoglobulin A (IgA), IgM, and IgG responses from 20 patients with early-onset per iodontitis (EOP), 20 patients with adult periodontitis (AP), and 20 ag e- and sex-matched healthy controls were examined by immunoblot analys is. A recombinant collagenase antigen used for the immunoblot analysis was produced by using the plasmid pGEX-2T, which allows the fusion be tween the collagenase and glutathione S-transferase. There was no sign ificant difference in collagenase-specific IgG antibody detection betw een samples from the EOP, AP, and control groups. In contrast, 85% of AP and EOP sera had collagenase-specific IgA antibodies, whereas only 20% of control sera showed collagenase-specific IgA reactivity. Plaque samples from all groups were assessed by PCR with primers complementa ry to the collagenase-encoding gene prtC. The results indicated that 9 0% of AP and EOP plaque samples and 10% of control samples were positi ve for P. gingivalis. All patients with collagenase-specific IgA antib odies were PCR positive. The results of the study indicate a nearly co mplete concordance (k = 0.856) between the presence of collagenase-spe cific IgA antibodies and PCR detection of P. gingivalis. By using PCR as the ''gold standard,'' the sensitivity and specificity of the IgA i mmunoblot test were 94.7 and 90.9%, respectively. Therefore, the recom binant collagenase is a potential candidate for use in the serodiagnos is of periodontitis.