Helicobacter pylori urease significantly reduces opsonization by human complement.
The role of Helicobacter pylori urease in opsonization by human complement was investigated. H. pylori wild type strain N6 and isogenic mutants lacking either the large urease subunit (UreB) or an accessory urease protein (UreG) were incubated with different sera. C3b bound to the bacteria was measured by specific staining and flow cytometry. As compared with opsonization of N6 and the UreG-lacking mutant, opsonization of the UreB-lacking mutant was significantly increased after incubation with sera from both H. pylori uninfected (P<.001) or infected (P<.05) persons. However, when sera from uninfected persons were used, effective opsonization of this mutant proved to be dependent mainly on the classical pathway of complement activation. Irrespective of the serum used, opsonization values were very low after selective inactivation of the classical or the alternative pathway. Reduced opsonization of the urease-expressing strains could, to some extent, result from degradation of bound C3b.
Department of Clinical Microbiology, Hygiene-Institute of the University of Vienna, Austria.
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Rokita
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Makristathis
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Presterl
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ML
Rotter
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AM
Hirschl
D001426:Bacterial Proteins / Q000502:physiology; D002352:Carrier Proteins / Q000502:physiology; D002469:Cell Separation; D003176:Complement C3 / Q000276:immunology*; D003179:Complement C3b / Q000276:immunology; D015932:Complement C3c / Q000276:immunology; D015933:Complement C3d / Q000276:immunology; D005434:Flow Cytometry; D016480:Helicobacter pylori / Q000201:enzymology*; D006801:Humans; D066298:In Vitro Techniques; D009895:Opsonin Proteins / Q000378:metabolism*; D028044:Phosphate-Binding Proteins; D014510:Urease / Q000378:metabolism*
D001426:Bacterial Proteins; D002352:Carrier Proteins; D003176:Complement C3; D009895:Opsonin Proteins; D028044:Phosphate-Binding Proteins; C082270:ureG protein, Bacteria; D003179:Complement C3b; D015932:Complement C3c; D015933:Complement C3d; D014510:Urease