Functional characteristics of antibodies induced by Arg‐gingipain (HRgpA) and Lys‐gingipain (Kgp) from Porphyromonas gingivalis

Abstract

Arginine-specific gingipain (HRgpA) and lysine-specific gingipain (Kgp), enzymes produced by Porphyromonas gingivalis, may be candidates for an anti-P. gingivalis vaccine. The purpose of our study was to determine whether HRgpA and Kgp have opsonic target sites and whether these sites are available and accessible on intact P. gingivalis cells. Rabbits were used to generate polyclonal antibodies to both proteins. Animals were immunized and immunoglobulin G (IgG) fractions were isolated from preimmune and immune sera. Functional characteristics of the antibodies were assessed by determining antibody titers by enzyme-linked immunosorbent assay (ELISA), generating Western immunoblots, and measuring antibody enhancement of P. gingivalis opsonization, phagocytosis and killing by polymorphonuclear leukocytes (PMN) of intact cells of strains of P. gingivalis representative of the four serotypes. Strains studied included 33277 (serotype A), A7A1-28 (serotype B), W50 (serotype C) and 381 (serotype D). Both HRgpA and Kgp induced high titers of IgG antibody. Anti-HRgpA and anti-Kgp bound to both HRgpA and Kgp demonstrating a large proportion of shared antigenic epitopes. The two antibodies bound equally well to all four P. gingivalis serotypes with titers ranging from 77 to 205 ELISA units when compared to preimmune IgG set at 1 ELISA unit. The immunoblot patterns of binding of the two antibodies to HRgpA and Kgp and to sonicates of the four P. gingivalis serotypes were virtually identical. Both antibodies detected components in HRgpA at 27, 35 and 45 kDa and in Kgp at 27, 32, 35, 40 and 55 kDa. The antibodies also detected components at or near these same positions in addition to multiple high molecular mass components in the cell sonicates of P. gingivalis. Both proteins induced antibodies that significantly enhanced opsonization as assessed by chemiluminescence, with values ranging from 130 mV to 375 mV for anti-HRgpA IgG and from 240 mV to 475 mV for anti-Kgp IgG. Both antibodies significantly enhanced PMN-mediated bacterial killing of the four P. gingivalis serotypes, although the percentage of killing varied among the serotypes (24-81% for anti-HRgpA and 37-89% for anti-Kgp). Thus, both HRgpA and Kgp express opsonic target sites and induce high titers of antibodies that opsonize and enhance killing of all four serotypes of P. gingivalis. These two proteins appear to be potential candidate antigens for an anti-P. gingivalis vaccine.

Arg-gingipain A DNA Vaccine Prevents Alveolar Bone Loss in Mice

“…Mice immunized with RgpA polypeptides were protected from P. gingivalis-elicited oral bone loss, with this antigen also eliciting a potent IgG response (Gibson et al, 2001). In addition, IgG against purified RgpA also showed a protective effect, enhancing PMN-mediated bacterial killing of P. gingivalis strains (Nakagawa et al, 2001). When these findings are considered together with the present results, it seems clear that IgG can exert a preventive effect against components of P. gingivalis.…”

Effects of egg yolk antibody against Porphyromonas gingivalis gingipains in periodontitis patients

“…Passive immunization with antibodies from several different species has been used as immunotherapy against dental caries (25,26) and periodontitis (27)(28)(29)(30)(31)(32). Previous studies have shown that antibodies are actively transported to the egg yolk of immunized hens (33).…”

Surface protease of Treponema denticola hydrolyzes C3 and influences function of polymorphonuclear leukocytes

“…Our previous results have indicated that the protease mutant forms significantly smaller lesions in mice than does the wild type [24]. Further study is needed to elucidate the role of the activation of PMNs by dentilisin in colonization by T. denticola and inflammation of periodontal tissue.…”