Serum antibody reactivity against recombinant PrtC of Porphyromonas gingivalis following periodontal therapy

Objectives: In 34 patients with chronic periodontitis, the presence of IgA, IgG, and IgG subclass serum antibodies against recombinant PrtC (rPrtC) of Porphyromonas gingivalis was assessed by immunoblot analysis 24 months after therapy. Methods: rPrtC was produced from P. gingivalis ATTC 33277 using the plasmid pGEX-2T. In addition. intraoral colonization with P. gingivalis was detected by PCR in subgingival plaque and swab samples from buccal mucosae, tonsils and tongue at baseline. 10 d. and 3, 6, 9, 11 18, and 24 months. Results: All patients were found to harbor P. gingivalis in the oral cavity at least once during the observation period. The identified antibody responses against the rPrtC of P. gingivalis were IgA (970, i.e. 3334 patients) and IgG (100%, i.e. 34, 34). with an IgG subclass distribution of IgG2 (65%, r.e. 22/34 patients) > IgG3 (47%. i.e. 16 34) > IgG1 (38% i.e. 13 34) > IgG4 (29%,. i.e. 10 34). Anti-rPrtC IgA and IgG antibody reactivity was found in all but one patients (anti-rPrtC IgA negative). who tested negative for P. gingivalis at all of the assessed intraoral sites for at least 6 months before sera collection. There was no association between IgG subclass reactivity against the rPrtC of P. gingivalis and progression of periodontal attachment loss. Conclusion: The results indicated that anti-rPrtC IgA and IgG antibodies may serve as an indicator for past or present intraoral colonization with P. gingivalis.