IMMUNIZATION WITH PORPHYROMONAS-GINGIVALIS CYSTEINE PROTEASE - EFFECTS ON EXPERIMENTAL GINGIVITIS AND LIGATURE-INDUCED PERIODONTITIS IN MACACA-FASCICULARIS

TARGETING BACTERIAL VIRULENCE FACTORS such as proteases for immunizati on may hold the key to limiting or preventing loss of attachment and a lveolar bone in periodontal disease. This study examined the clinical, microbiological, and immunological responses following active immuniz ation with a purified Porphyromonas gingivalis cysteine protease (porp hypain-2) in the nonhuman primate (Nhp) Macaca fascicularis. One group of Nhp was immunized with porphypain-2 antigen while control Nhp rece ived placebo injections. All Nhp were subjected to experimental gingiv itis followed by ligature-induced periodontitis in a split-mouth desig n. An enzyme-linked immunosorbent assay demonstrated that immunization elicited a significantly elevated and specific IgG antibody response to both whole cell P, gingivalis (36-fold) and to porphypain-2 (194-fo ld). Checkerboard hybridization DNA analysis of subgingival plaque fro m Ligated sextants demonstrated that 25% more Gram-negative anaerobic species became significantly elevated from baseline and at earlier tim epoints in the control group than in the immunized group. Immunization with this protease did not suppress the emergence of P, gingivalis. C linical indices showed few changes related to immunization. Alveolar b one density changes demonstrated a highly significant loss in ligated sextants compared to non-ligated sextants within the control group (P < 0.001), and a smaller but significant difference within the immunize d group (P = 0.043). Comparison of ligated sextants only demonstrated more bone loss in the control group versus the immunized group (-13.07 +/- 9.51 versus -9.41 +/- 6.18; computer-assisted densitometric image analysis units +/- SD); the difference approached, but did not reach, significance. The results suggest that porphypain-2 may contribute to the pathogenic potential of the subgingival plaque microbiota in the Nhp model of ligature-induced periodontitis, and that active immunizat ion with porphypain-2 appeared capable of altering this pathogenic res ponse.