Bactericidal activity of a monoclonal antibody against a recombinant 40-kDa outer membrane protein of Porphyromonas gingivalis.
BACKGROUND
We have cloned the gene for a 40-kDa outer membrane protein (40-kDa OMP) from Porphyromonas gingivalis 381. The recombinant (r)40-kDa OMP has become the subject of considerable interest because of its potential role in the development of a vaccine useful for passive immunization. To develop such a vaccine, it is essential to fully understand the functions of anti-r40-kDa OMP antibody in the host defense against P. gingivalis. To that end, we developed a panel of monoclonal antibodies by immunizing mice with purified r40-kDa OMP. The objective of this study was to determine the bactericidal activity on P. gingivalis by the IgG1 monoclonal antibody Pg-ompA2.


METHODS
Bacterial growth measurement, a complement-mediated anti-P. gingivalis assay based on [3H]thymidine uptake, and a 14C-release assay were performed to test the bactericidal activity of Pg-ompA2 to P. gingivalis.


RESULTS
In the presence of complement, Pg-ompA2 was lethal to P. gingivalis 381 as well as to the more virulent P. gingivalis strains, including ATCC 53977 and W83. Using component-deficient complement, we determined that Pg-ompA2 killed P. gingivalis by activating both the classical and alternative complement pathways.


CONCLUSIONS
Pg-ompA2 has an in vitro complement-mediated bactericidal activity to P. gingivalis. Pg-ompA2 may contribute to the development of a local immunotherapy that can be applied in the gingival crevice of a patient with P. gingivalis-related periodontitis, or be a vaccine candidate.
Katoh
M
M
Department of Biochemistry, Nihon University School of Dentistry at Matsudo, Chiba, Japan.
Saito
S
S
Takiguchi
H
H
Abiko
Y
Y
D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology* / Q000627:therapeutic use; D000911:Antibodies, Monoclonal / Q000276:immunology* / Q000627:therapeutic use; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology*; D001428:Bacterial Vaccines / Q000138:chemical synthesis; D002250:Carbon Radioisotopes; D003001:Cloning, Molecular; D003170:Complement Pathway, Alternative / Q000276:immunology; D003171:Complement Pathway, Classical / Q000276:immunology; D003165:Complement System Proteins / Q000276:immunology; D005260:Female; D006168:Guinea Pigs; D006801:Humans; D007116:Immunization, Passive; D007074:Immunoglobulin G / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D010518:Periodontitis / Q000382:microbiology / Q000517:prevention & control; D016966:Porphyromonas gingivalis / Q000254:growth & development / Q000276:immunology*; D019275:Radiopharmaceuticals; D011994:Recombinant Proteins; D013936:Thymidine / Q000378:metabolism; D014316:Tritium; D014774:Virulence
D000907:Antibodies, Bacterial; D000911:Antibodies, Monoclonal; D001425:Bacterial Outer Membrane Proteins; D001428:Bacterial Vaccines; D002250:Carbon Radioisotopes; D007074:Immunoglobulin G; D019275:Radiopharmaceuticals; D011994:Recombinant Proteins; D014316:Tritium; D003165:Complement System Proteins; D013936:Thymidine