title: Serodiversity of opsonic antibodies against Enterococcus faecalis--glycans of the cell wall revisited.
abstract: In a typing system based on opsonic antibodies against carbohydrate antigens of the cell envelope, 60% of Enterococcus faecalis strains can be assigned to one of four serotypes (CPS-A to CPS-D). The structural basis for enterococcal serotypes, however, is still incompletely understood. Here we demonstrate that antibodies raised against lipoteichoic acid (LTA) from a CPS-A strain are opsonic to both CPS-A and CPS-B strains. LTA-specific antibodies also bind to LTA of CPS-C and CPS-D strains, but fail to opsonize them. From CPS-C and CPS-D strains resistant to opsonization by anti-LTA, we purified a novel diheteroglycan with a repeating unit of →6)-β-Galf-(1→3)- β-D-Glcp-(1→ with O-acetylation in position 5 and lactic acid substitution at position 3 of the Galf residue. The purified diheteroglycan, but not LTA absorbed opsonic antibodies from whole cell antiserum against E. faecalis type 2 (a CPS-C strain) and type 5 (CPS-D). Rabbit antiserum raised against purified diheteroglycan opsonized CPS-C and CPS-D strains and passive protection with diheteroglycan-specific antiserum reduced bacterial counts by 1.4-3.4 logs in mice infected with E. faecalis strains of the CPS-C and CPS-D serotype. Diheteroglycan-specific opsonic antibodies were absorbed by whole bacterial cells of E. faecalis FA2-2 (CPS-C) but not by its isogenic acapsular cpsI-mutant and on native PAGE purified diheteroglycan co-migrated with the gene product of the cps-locus, suggesting that it is synthesized by this locus. In summary, two polysaccharide antigens, LTA and a novel diheteroglycan, are targets of opsonic antibodies against typeable E. faecalis strains. These cell-wall associated polymers are promising candidates for active and passive vaccination and add to our armamentarium to fight this important nosocomial pathogen.
authors: University Medical Center Freiburg, Freiburg, Germany.
authors: Christian
authors: C
authors: Theilacker
authors: Zbigniew
authors: Z
authors: Kaczyński
authors: Andrea
authors: A
authors: Kropec
authors: Irina
authors: I
authors: Sava
authors: Libin
authors: L
authors: Ye
authors: Anna
authors: A
authors: Bychowska
authors: Otto
authors: O
authors: Holst
authors: Johannes
authors: J
authors: Huebner
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood* / Q000276:immunology*; D000918:Antibody Specificity / Q000276:immunology; D000942:Antigens, Bacterial / Q000276:immunology; D016470:Bacteremia / Q000276:immunology / Q000517:prevention & control; D016667:Bacterial Capsules / Q000276:immunology / Q000302:isolation & purification; D002473:Cell Wall / Q000276:immunology*; D003429:Cross Reactions / Q000276:immunology; D004195:Disease Models, Animal; D013293:Enterococcus faecalis / Q000276:immunology*; D056426:Genetic Loci / Q000235:genetics; D008070:Lipopolysaccharides / Q000276:immunology; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D009895:Opsonin Proteins / Q000276:immunology*; D010587:Phagocytosis / Q000276:immunology; D011134:Polysaccharides / Q000737:chemistry / Q000276:immunology*; D011817:Rabbits; D040681:Structural Homology, Protein; D013682:Teichoic Acids / Q000276:immunology; D014611:Vaccination
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D008070:Lipopolysaccharides; D009895:Opsonin Proteins; D011134:Polysaccharides; D013682:Teichoic Acids; C009900:lipoteichoic acid