Antibody Responses to Arg-gingipain of Porphyromonas gingivalis in Periodontitis Patients

Arginine-specific cysteine proteinase (Arg-gingipain: Rgp) produced by Porphyromonas gingivalis is a major virulence factor of this periodontal pathogen, which is thought to play an important role in periodontitis by interrupting host defense mechanisms and by participating in the penetration and destruction of host connective tissues. We studied the IgG response against Rgp A components in patients with early-onset periodontitis (EOP) and adult periodontitis (AP) . We cloned3 fragments of rgpA (r-Rgp CAT, r-Rgp 44, and r-Rgps 15-27, corresponding to amino acid residues 228 to 719, 720 to 1136, and 1137 to 1704) and purified recombinant RgpA components. The IgG antibody titers in sera obtained from patients with 29 EOP, 53 AP, and 22 periodontally healthy subjects (controls) were evaluated by enzyme-linked immunosorbent assay (ELISA) . IgG titers against whole cell antigens of P.gingivalis ATCC 33277, r-Rgp 44, and r-Rgps 15-27 were significantly higher in EOP and AP patients than in controls (p<0.0001) . In IgG titer against r-Rgp CAT, howevers no significant difference was seen between AP patients and controls, in dicating that antibody production against r-Rgp CAT is difficult in AP patients. Oun findings suggest that the low responsiveness of antibody products to the RgpA catalytic domain is a factor in AP development. J. Jpn. Soc. Periodontal., 43: 240-250, 2001.