The present report reviews data implicating Actinobacillus actinomycetemcomitans in the etiology of human periodontal disease. Recent data are also presented relative to: (1) serological studies of this microorganism using monoclonal antibodies and the serodiagnosis of A. actinomycetemcomitans infections; (2) characterization of the serotype antigens; (3) studies of the serotype distribution of A. actinomycetemcomitans in extra-oral infections; and (4) examination of the correlation between A. actinomycetemcomitans colony morphology and fimbriae.

A new Treponema species, for which we propose the name Treponema medium, was isolated from subgingival plaque from an adult with periodontal disease. The morphological characteristics, differential biochemical characteristics, and protein profiles on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels of this organism are described. The guanine-plus-cytosine content of the DNA of T. medium is 51 mol%. The levels of DNA-DNA relatedness of the new species to other Treponema species, including Treponema denticola, Treponema vincentii, Treponema socranskii, Treponema pallidum, and Treponema phagedenis, are less than 30%. A phylogenetic analysis based on 16s rRNA sequences distinguished the new Treponema strain from strains belonging to previously described Treponema species. The type strain of T. medium is strain G7201.The incidence and numbers of treponemes in the human gingival flora become greater as gingivitis becomes more severe (27). The number of treponemes increases to approximately more than 50% of all bacterial morphotypes in subgingival samples from periodontitis patients (10,12,13,27). Some oral treponemal species have been associated with soft-tissue damage due to proteolytic enzymes or with inflammatory reactions due to antibodies against their specific antigens, and eventually this leads to periodontal tissue destruction in certain types of periodontal disease (12,18,21,36). Simonson et al., for instance, have reported that Treponema denticola is linked to the severity of periodontal disease (25). All of the human oral spirochetes mentioned above belong to the genus Treponema in the family Spirochaetaceae; these bacteria characteristically are tightly coiled organisms that consist of a protoplasmic cylinder (length, approximately 6 to 20 pm; width, 0.1 to 0.5 pm) covered by an envelope (an outer sheath) and periplasmic flagella (axial flagella) which originate subterminally at the ends of the protoplasmic cylinder (26). Choi et al. used a 16s rRNA gene cloning technique to document the qualitative nature of human oral spirochetes and demonstrated that there is great genetic diversity in oral spirochetes, even in a single periodontitis patient (2). Human oral spirochetes, however, have been conventionally grouped into the following three morphotypes: (i) small spirochetes, including T. denticola, Treponema socranskii, and Treponema pectinovorum; (ii) medium-sized spirochetes, such as Treponema vincentii; and (iii) large spirochetes which have not been isolated in pure culture (3, 11). related spirochete with different periodontal status and reported that human oral spirochetes were not uniformly distributed within the dentition or around individual teeth T. denticola, T. socranskii, T. pectinovorum, T. vincentii,We isolated Treponema sp. strain G7201T (T = type strain), which could not be classified in any previously described species. We examined the phenotypic, serologic, and genetic characteristics of this organism and compared the results with data for reference species.In this paper we ...

The polypeptides of seven strains of human treponemes were investigated by immunoblot analysis for their binding to the human placental collagens and laminin. Of the treponemal polypeptides, eleven polypeptides, 45‐kDa, 49‐kDa, and 62‐kDa polypeptides from T. pallidum ATCC 27087, a 48‐kDa polypeptide from T. phagedenis biotype Reiter, 51‐kDa and 53‐kDa polypeptides from T. vincentii ATCC 35580, 30‐kDa, 53‐kDa and 63‐kDa polypeptides from T. socranskii subsp. buccale ATCC 35534, a 52‐kDa polypeptide from T. denticola ATCC 35405, and a 53‐kDa polypeptide from T. denticola ATCC 33520 possessed an ability to bind to the laminin, type I, III, IV, or V collagen. An intermediate‐sized human oral isolate strain G7201 did not possess any laminin‐ or collagen‐binding polypeptides. Immunoelectron microscopy using intact treponemal cells with a single collagen‐binding polypeptide and the corresponding antisera demonstrated that the 51‐kDa and 53‐kDa polypeptides from T. vincentii, the 53‐kDa polypeptide from T. socranskii subsp. buccale ATCC 35534 and the 52‐kDa polypeptide from T. denticola ATCC 35405, were outer envelope proteins.

Major polypeptides from a human oral spirochete Treponema denticola ATCC 33520 were examined to demonstrate their ability to bind to human plasma fibronectin by immunoblot analysis. Of three main polypeptides separated on sodium dodecyl sulfate polyacrylamide gels 53,000-daltons (53-kDa) and 72-kDa surface antigenic proteins and a 38-kDa axial flagellar protein showed the ability to bind to fibronectin, suggesting that fibronectin on host cells can mediate cytoadherence of T. denticola by its binding to the surface proteins or the exposed 38-kDa axial flageller protein.

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.