Immunochemical characterization of a polysaccharide antigen isolated from the oral microorganismEubacterium saburreum, strain 02/725

Immunochemical and structural characterization of the antigenic polysaccharide from Eubacterium saburreum T18

An antigenic surface polysaccharide produced by Eubacterium saburreum strain T18, isolated from human dental plaque, was purified from formamide extract of whole cells. Methylation analysis, Smith degradation, optical rotation data and nuclear magnetic resonance spectra demonstrated that the purified antigen was a homopolysaccharide composed of D-glycero-D-galacto-heptose (Hep.) residues. The structure of the repeating unit in the polysaccharide was: -[----6)-[alpha-Hep.furanosyl-(1----4)]-beta-Hep.pyranosyl- (1----6)-[alpha-Hep.furanosyl-(1----2), alpha-Hep.furanosyl-(1----4)]-beta- Hep.pyranosyl-(1-)4----6)-beta-Hep.pyranosyl-(1----. No heptose residues were acetylated. Immunodiffusion reactions in agar gel suggested that the immunodeterminant of the antigenic polysaccharide was D-glycero-D-galacto-heptofuranosyl residues as branched nonreducing terminals.

Another polysaccharide antigen of Eubacterium saburreum with heptose as the main constituent

The polysaccharide antigen of Eubacterium saburreum strains L76, reacting by precipitation and complement-fixation, has D-glycero-D-galacto-heptose as the main component, and, in addition, O-acyl groups.

Chemical composition and immunological characterization of polysaccharide antigen from Eubacterium saburreum T18

Two types of polysaccharide were obtained from the oral microorganism Eubacterium saburreum T18 by formamide extraction and subsequent gel filtration and ion-exchange chromatography. One polysaccharide, which was composed of D-glycero-D-galacto-heptose, had antigenic activity in an immunoprecipitation reaction with rabbit anti-T18 serum due to immunoglobulin M antibodies. The second polysaccharide was composed of D-glycero-D-manno-heptose and L-rhamnose, but it did not have immunoprecipitation activity. These polysaccharide antigens were not alkali labile and differed from E. saburreum L44 and T27 antigens, which were composed of D-glycero-D-galacto-heptose.

Reaction of human sera with Eubacterium brachy: isolation and characterization of an extracellular antigen

Recent studies have demonstrated an association of Eubacterium sp. with the subgingival microflora of patients with chronic periodontitis. One species, Eubacterium brachy, was evaluated to determine the possible mechanisms by which this microorganism may contribute to these diseases. Of 167 sera evaluated by double diffusion in agar, 20.8% displayed reactivity with a sonicated preparation of E. brachy. An extracellular antigen was identified in the culture supernatant fluid which reacted with antibodies in human sera. This antigen was isolated by methanol precipitation and purified by gel filtration. When tested by an enzyme-linked immunosorbent assay, all sera displayed some reactivity. Lines of identity were not shared with other species of Eubacterium, but were shared with other clinical isolates of E. brachy. The reactive antibody was identified as immunoglobulin G by immunoelectrophoresis, verified by enzyme-linked immunosorbent assay, and found to be capable of complement fixation. The monosaccharides and amino acids of the extracellular antigen were identified by high-pressure liquid chromatography. This antigen was shown to have a molecular weight of 170,000 and to share a line of identity with the sonicated preparation of E. brachy. The possible role of the organism in the immunopathology of periodontal diseases is discussed.

Eubacterium saburreum L13 antigen containing a ketohexose as a main sugar constituent

A periodate-resistant antigen (PS L13) which contained ketohexose and glucose was isolated from the oral microorganism Eubacterium saburreum L13 by trypsin digestion and subsequent gel filtration and ion-exchange chromatography. The ketohexose reacted as fructose would in colorimetric and chromatographic analyses, but not in gas-liquid chromatography. Rabbit antiserum to E. saburreum L13 agglutinated the bacteria and contained precipitins of the immunoglobulin G class specific for PS L13.