title: Binding of the capsule-like serotype-specific polysaccharide antigen and the lipopolysaccharide from Actinobacillus actinomycetemcomitans to human complement-derived opsonins.
abstract: We investigated the molecular mechanism of resistance of Actinobacillus actinomycetemcomitans to complement-dependent chemiluminescence response by human polymorphonuclear leukocytes. Whole cells of serotype b-specific polysaccharide antigen-defective mutants ST2 and ST5 were constructed by inserting transposon Tn916 into A. actinomycetemcomitans strain Y4. These strains induced strong chemiluminescence response by human polymorphonuclear leukocytes and markedly bound to human complement-derived opsonins. In contrast, strain Y4 induced weak chemiluminescence response and weakly bound to complement-derived opsonins. The biosensor analysis revealed that lipopolysaccharide from strain Y4 strongly bound to human C3b, but serotype b-specific polysaccharide antigen did not. The serotype b-specific polysaccharide antigen molecule might sterically hinder the interaction between complement-derived opsonins and lipopolysaccharide to reduce complement-dependent chemiluminescence response by human polymorphonuclear leukocytes.
authors.affiliation: Department of Preventive Dentistry, Kyushu University Faculty of Dentistry, Fukuoka, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Yamaguchi
authors.forename: H
authors.initials: H
authors.lastname: Tsuda
authors.forename: Y
authors.initials: Y
authors.lastname: Yamashita
authors.forename: T
authors.initials: T
authors.lastname: Koga
mesh_terms: D000328:Adult; D016976:Aggregatibacter actinomycetemcomitans / Q000276:immunology* / Q000378:metabolism / Q000472:pathogenicity; D000907:Antibodies, Bacterial / Q000378:metabolism; D000942:Antigens, Bacterial / Q000378:metabolism*; D016667:Bacterial Capsules / Q000276:immunology; D001667:Binding, Competitive; D003179:Complement C3b / Q000276:immunology / Q000378:metabolism; D006801:Humans; D008070:Lipopolysaccharides / Q000378:metabolism; D008163:Luminescent Measurements; D016254:Mutagenesis, Insertional; D009504:Neutrophils / Q000276:immunology; D009895:Opsonin Proteins / Q000276:immunology / Q000378:metabolism; D011135:Polysaccharides, Bacterial / Q000276:immunology / Q000378:metabolism*; D011485:Protein Binding; D012703:Serotyping; D014774:Virulence
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D008070:Lipopolysaccharides; D009895:Opsonin Proteins; D011135:Polysaccharides, Bacterial; D003179:Complement C3b