title: Mechanism of YadA-mediated serum resistance of Yersinia enterocolitica serotype O3.
abstract: Complement activation via the alternative pathway was analyzed with isogenic strains of Yersinia enterocolitica serotype O3 differing in plasmid content (p- or p+ strains) or selective lack of YadA expression (YadA- strain). The p+ strain was serum resistant, even after antibody-enhanced complement activation. Serum sensitivity was observed with the p- and YadA- strains but was more pronounced in the p- strain. The p+ strain deposited less C5b-9(m) complexes on its surface than the p- and YadA- strains. No size difference, however, was detected with solubilized C5b-9(m) complexes obtained from resistant and sensitive strains. At the C3 level, it became evident that surface-bound C3b was degraded faster into iC3b on the p+ strain than on the p- and YadA- strains. Our results demonstrate that YadA inhibits complement activation at the C3 and C9 level. As a result, reduced amounts of C5b-9(m) are generated on the surface of YadA-bearing bacteria. In addition, YadA seems to protect against the lytic action of those C5b-9(m) complexes whose deposition could not be prevented.
authors.affiliation: Institut für Klinische Mikrobiologie, Universität Erlangen-Nürnberg, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Pilz
authors.forename: T
authors.initials: T
authors.lastname: Vocke
authors.forename: J
authors.initials: J
authors.lastname: Heesemann
authors.forename: V
authors.initials: V
authors.lastname: Brade
mesh_terms: D018829:Adhesins, Bacterial; D001345:Autoradiography; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology*; D002499:Centrifugation, Density Gradient; D003176:Complement C3 / Q000378:metabolism; D003186:Complement C9 / Q000378:metabolism; D003170:Complement Pathway, Alternative / Q000276:immunology; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D066298:In Vitro Techniques; D010957:Plasmids / Q000276:immunology; D015008:Yersinia enterocolitica / Q000472:pathogenicity*
chemical_list: D018829:Adhesins, Bacterial; D001425:Bacterial Outer Membrane Proteins; D003176:Complement C3; D003186:Complement C9; C064832:YadA protein, Yersinia