The ability of fresh isolates of B. gingivalis to establish abscesses in the mouse model was studied by comparing them with established laboratory strains of B. gingivalis. Eight fresh isolates obtained from plaque associated with periodontal disease and grown under similar conditions as established strains were injected subcutaneously on the back of the mouse. All of these strains produced secondary lesions on the abdomen. Septicemia was associated with seven of the strains. Two commonly used laboratory strains, W50 and W83, also produced secondary lesions and septicemia. Five other laboratory strains produced only localized abscesses. On histologic examination, the strains that produced disseminated disease showed invasion of connective disease by individual bacteria that were not in clumps. The strains that produced localized abscesses were characterized by growing in colonies or clumps in the abscess cavity. Four synthetic enzyme substrates were examined to determine whether the differences between invasive and non-invasive strains were due to differences in proteolytic enzyme production. No differences in enzyme production could be demonstrated with the selected substrates.

Protease and peptidase enzymes are thought to play a role in the virulence of many oral organisms, especially those associated with periodontal diseases. In order to evaluate the peptidases of periodontopathogens, we compared the arylaminopeptidase activities of Bacteroides gingivalis with those of other oral and non-oral bacteria. Sixty-three bacterial strains representing the prominent cultivable organisms in human periodontal pockets were tested, including representatives of the black-pigmented Bacteroides, Actinobacillus, Actinomyces, Campylobacter, Capnocytophaga, Eikenella, Fusobacterium, Haemophilus, Lactobacillus, Streptococcus, and Veillonella species. Each micro-organism was examined for its ability to hydrolyze 18 synthetic substrates of beta-naphthylamide derivatives of amino acids, dipeptides, and tripeptides. Quantitation of the enzyme activity was accomplished by colorimetric measurement of the amounts of released beta-naphthylamines. N-CBz-glycyl-glycyl-L-arginine-beta-naphthylamide was readily cleaved by B. gingivalis, but slightly or not at all by the other oral strains tested. L-arginine-beta-naphthylamide was cleaved by B. gingivalis, Capnocytophaga species, and Streptococcus species, but not readily by the other Bacteroides strains. Some dipeptide substrates tested, such as glycyl-L-arginine- and glycyl-L-proline-beta-naphthylamide, were strongly cleaved by B. gingivalis and weakly cleaved by other Bacteroides strains. Since high levels of N-CBz-glycyl-glycyl-L-arginyl-aminopeptidase activity are characteristic of B. gingivalis, its measurement may be valuable in the identification of this organism in clinical samples as an aid in diagnosis and monitoring of periodontal infections. Furthermore, this and other aminopeptidases produced by B. gingivalis and other oral organisms may play a role in the tissue destruction seen in periodontal disease.

We identify a novel, orally active antihypertensive peptide, LRA from the digest of rice bran protein.

Bacteroides gingivalis produces large amounts of proteolytic enzymes which may play a role in its virulence. These enzymes may participate in the tissue destruction of the inflammatory process. In this study, the characteristics of two such enzymes, N‐CBz‐glycyl‐glycyl‐arginyl peptidase (N‐CBz‐Gly‐Gly‐Arg peptidase) and glycyl‐prolyl peptidase (Gly‐Pro peptidase) were investigated. The enzymes eluted in different peaks from an anion exchange column. N‐CBz‐Gly‐Gly‐Arg peptidase was associated with cells up to 48 h in culture. If cultured longer, it also released in the supernatant. It exhibited optimal activity between pH of 7.0 and 7.5 and was readily inactivated by heat treatment (45°C for 15 min). The enzyme activity was inhibited by p‐chloromercuribenzoic acid (PCMB), leupeptin and antipain, suggesting that it is a thiol protease. The B. gingivalis N‐CBz‐Gly‐Gly‐Arg peptidase was different from the serum enzyme that digests the same substrate. The serum enzyme was more resistant to heat treatment and was inhibited by diisopro‐pylfluorophosphate (DFP). B. gingivalis also produced Gly‐Pro peptidase that is released in the supernatant. The enzyme has an optimal pH range between 7.5 and 8.0. The B. gingivalis Gly‐Pro peptidase was inhibited by DFP, suggesting that it represents a serine protease. The serum Gly‐Pro peptidase did not differ from the bacterial enzyme with respect to its sensitivity to inhibitors; however, they were markedly different in heat sensitivity. The bacterial enzyme was completely inactivated at 60°C for 30 min, whereas the serum enzyme was not inactivated even at 1 h at 60°C.

Human oral spirochetes are prominent inhabitants of subgingival plaque in patients with periodontal disease. By immunoelectron microscopy using protein A-gold complexes and either polyclonal mouse antiserum against the 53-kDa antigen or 53-kDa-antigen-specific monoclonal antibody, a major polypeptide antigen, with a molecular weight of 53,000 (molecular size, 53 kilodaltons [kDa]), of a human oral spirochete, Treponema denticola ATCC 33520, was found to localize on the surface of the outer envelope.