title: Evidence for a LOS and a capsular polysaccharide in Capnocytophaga canimorsus.
abstract: Capnocytophaga canimorsus is a dog's and cat's oral commensal which can cause fatal human infections upon bites or scratches. Infections mainly start with flu-like symptoms but can rapidly evolve in fatal septicaemia with a mortality as high as 40%. Here we present the discovery of a polysaccharide capsule (CPS) at the surface of C. canimorsus 5 (Cc5), a strain isolated from a fulminant septicaemia. We provide genetic and chemical data showing that this capsule is related to the lipooligosaccharide (LOS) and probably composed of the same polysaccharide units. A CPS was also found in nine out of nine other strains of C. canimorsus. In addition, the genomes of three of these strains, sequenced previously, contain genes similar to those encoding CPS biosynthesis in Cc5. Thus, the presence of a CPS is likely to be a common property of C. canimorsus. The CPS and not the LOS confers protection against the bactericidal effect of human serum and phagocytosis by macrophages. An antiserum raised against the capsule increased the killing of C. canimorsus by human serum thus showing that anti-capsule antibodies have a protective role. These findings provide a new major element in the understanding of the pathogenesis of C. canimorsus.
authors.affiliation: Université de Namur, URBM, 5000 Namur, Belgium.
authors.forename: Francesco
authors.initials: F
authors.lastname: Renzi
authors.affiliation: Infection Biology, Biozentrum der Universität Basel, CH4056 Basel, Switzerland.
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Ittig
authors.affiliation: Université du Littoral-Côte d'Opale, Institut Charles Violette, EA7394, 62327 Boulogne-sur-mer, France.
authors.forename: Irina
authors.initials: I
authors.lastname: Sadovskaya
authors.affiliation: Université de Namur, URBM, 5000 Namur, Belgium.
authors.forename: Estelle
authors.initials: E
authors.lastname: Hess
authors.affiliation: Université de Namur, URBM, 5000 Namur, Belgium.
authors.forename: Frederic
authors.initials: F
authors.lastname: Lauber
authors.affiliation: Université de Namur, URBM, 5000 Namur, Belgium.
authors.forename: Melanie
authors.initials: M
authors.lastname: Dol
authors.affiliation: Infection Biology, Biozentrum der Universität Basel, CH4056 Basel, Switzerland.
authors.forename: Hwain
authors.initials: H
authors.lastname: Shin
authors.affiliation: Infection Biology, Biozentrum der Universität Basel, CH4056 Basel, Switzerland.
authors.forename: Manuela
authors.initials: M
authors.lastname: Mally
authors.affiliation: Infection Biology, Biozentrum der Universität Basel, CH4056 Basel, Switzerland.
authors.forename: Chantal
authors.initials: C
authors.lastname: Fiechter
authors.affiliation: BioEM lab, Biozentrum der Universität Basel, CH4056 Basel, Switzerland.
authors.forename: Ursula
authors.initials: U
authors.lastname: Sauder
authors.affiliation: BioEM lab, Biozentrum der Universität Basel, CH4056 Basel, Switzerland.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Chami
authors.affiliation: Université de Namur, URBM, 5000 Namur, Belgium.
authors.forename: Guy R
authors.initials: GR
authors.lastname: Cornelis
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology; D016667:Bacterial Capsules / Q000737:chemistry* / Q000276:immunology; D002206:Capnocytophaga / Q000737:chemistry* / Q000276:immunology / Q000472:pathogenicity; D002415:Cats; D004285:Dogs; D016905:Gram-Negative Bacterial Infections / Q000276:immunology; D006801:Humans; D008070:Lipopolysaccharides / Q000737:chemistry* / Q000276:immunology; D011135:Polysaccharides, Bacterial / Q000737:chemistry* / Q000276:immunology
chemical_list: D000907:Antibodies, Bacterial; D008070:Lipopolysaccharides; D011135:Polysaccharides, Bacterial; C023023:lipid-linked oligosaccharides