Characterization of anti-Porphyromonas gingivalis heat shock protein 60 monoclonal antibody

Objectives: Porphyromonas gingivalis (P. gingivalis) heat shock protein (HSP)60 may play a role in the immunopathogenesis of periodontitis as well as atherosclerosis by modulating autoimmune reaction due to its high level of sequence homology between bacteria and human counterpart. Hence, identifying immunodomiant epitope of P. gingivalis HSP60 that is reactive exclusively to the homologous bacteria without reacting with human HSP may comprise a critical strategy for development of a periodontal vaccine. The present study was performed to identify the peptide specifically recognized by anti-P. gingivalis HSP60 mono-reactive to P. gingivalis HSP60.

Methods: Four different hybridomas were cloned producing monoclonal IgG antibodies exclusively to P. gingivalis HSP60. 37 synthetic peptde (20-mer with 5-amino acid overlapping) were synthesized. All of these peptide were subject to SDS-PAGE for immunblot analysis.

Results: Peptide #29 and #19 were recognized by one of the four monoclonal antibodies that reacted soley with P. gingivalis HSP60. Immunohistochemsitry to identify the localization of the antibody in the diseased gingival tissues revealed that the P. gingivalis HSP60 peptide (TVPGGGTTYIRAIAALEGLK) were positively involved in the immunopathologic process of periodontal disease.

Conclusions: The peptide may potentially be developed as vaccine candidates. Further investigations are under way to identify more clones producing monoclonal antibodies reactive to P. gingivalis HSP and to other periodontopathogenic bacteria as well, while maintaining specificities to human counterpart.