title: An immune response directed to proteinase and adhesin functional epitopes protects against Porphyromonas gingivalis-induced periodontal bone loss.
abstract: Porphyromonas gingivalis, a pathogen associated with periodontitis, bound to fibrinogen, fibronectin, hemoglobin, and collagen type V with a similar profile to that of its major virulence factor, the cell surface RgpA-Kgp proteinase-adhesin complex. Using peptide-specific, purified Abs in competitive inhibition ELISAs and epitope mapping assays, we have identified potential adhesin binding motifs (ABMs) of the RgpA-Kgp complex responsible for binding to host proteins. The RgpA-Kgp complex and synthetic ABM and proteinase active site peptides conjugated to diphtheria toxoid, when used as vaccines, protected against P. gingivalis-induced periodontal bone loss in the murine periodontitis model. The most efficacious peptide and protein vaccines were found to induce a high-titer IgG1 Ab response. Furthermore, mice protected in the lesion and periodontitis models had a predominant P. gingivalis-specific IL-4 response, whereas mice with disease had a predominant IFN-gamma response. The peptide-specific Abs directed to the ABM2 sequence (EGLATATTFEEDGVA) protected against periodontal bone loss and inhibited binding of the RgpA-Kgp complex to fibrinogen, fibronectin, and collagen type V. Furthermore, the peptide-specific Abs directed to the ABM3 sequence (GTPNPNPNPNPNPNPGT) protected against periodontal bone loss and inhibited binding to hemoglobin. However, the most protective Abs were those directed to the active sites of the RgpA and Kgp proteinases. The results suggest that when the RgpA-Kgp complex, or functional binding motif or active site peptides are used as a vaccine, they induce a Th2 response that blocks function of the RgpA-Kgp complex and protects against periodontal bone loss.
authors.affiliation: Cooperative Research Centre for Oral Health Science, School of Dental Science, University of Melbourne, Victoria, Australia.
authors.forename: Neil M
authors.initials: NM
authors.lastname: O'Brien-Simpson
authors.forename: Rishi D
authors.initials: RD
authors.lastname: Pathirana
authors.forename: Rita A
authors.initials: RA
authors.lastname: Paolini
authors.forename: Yu-Yen
authors.initials: YY
authors.lastname: Chen
authors.forename: Paul D
authors.initials: PD
authors.lastname: Veith
authors.forename: Vivian
authors.initials: V
authors.lastname: Tam
authors.forename: Nafisa
authors.initials: N
authors.lastname: Ally
authors.forename: Robert N
authors.initials: RN
authors.lastname: Pike
authors.forename: Eric C
authors.initials: EC
authors.lastname: Reynolds
mesh_terms: D018829:Adhesins, Bacterial / Q000276:immunology* / Q000378:metabolism / Q000627:therapeutic use; D016301:Alveolar Bone Loss / Q000382:microbiology / Q000517:prevention & control*; D000818:Animals; D001422:Bacterial Adhesion; D001665:Binding Sites; D003546:Cysteine Endopeptidases / Q000378:metabolism / Q000627:therapeutic use; D000939:Epitopes / Q000276:immunology; D000080867:Gingipain Cysteine Endopeptidases; D007114:Immunization / Q000379:methods*; D051379:Mice; D008807:Mice, Inbred BALB C; D010447:Peptide Hydrolases / Q000276:immunology*; D010455:Peptides / Q000276:immunology / Q000627:therapeutic use; D010518:Periodontitis / Q000628:therapy*; D016966:Porphyromonas gingivalis / Q000276:immunology* / Q000472:pathogenicity; D025941:Protein Interaction Mapping; D018418:Th2 Cells / Q000276:immunology; D014612:Vaccines
chemical_list: D018829:Adhesins, Bacterial; D000939:Epitopes; D000080867:Gingipain Cysteine Endopeptidases; D010455:Peptides; D014612:Vaccines; D010447:Peptide Hydrolases; D003546:Cysteine Endopeptidases