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Resistance of Capnocytophaga canimorsus to killing by human complement and polymorphonuclear leukocytes.

ABSTRACT: Capnocytophaga canimorsus is a bacterium of the canine oral flora known since 1976 to cause rare but severe septicemia and peripheral gangrene in patients that have been in contact with a dog. It was recently shown that these bacteria do not elicit an inflammatory response (H. Shin, M. Mally, M. Kuhn, C. Paroz, and G. R. Cornelis, J. Infect. Dis. 195:375-386, 2007). Here, we analyze their sensitivity to the innate immune system. Bacteria from the archetype strain Cc5 were highly resistant to killing by complement. There was little membrane attack complex (MAC) deposition in spite of C3b deposition. Cc5 bacteria were as resistant to phagocytosis by human polymorphonuclear leukocytes (PMNs) as Yersinia enterocolitica MRS40, endowed with an antiphagocytic type III secretion system. We isolated Y1C12, a transposon mutant that is hypersensitive to killing by complement via the antibody-dependent classical pathway. The mutation inactivated a putative glycosyltransferase gene, suggesting that the Y1C12 mutant was affected at the level of a capsular polysaccharide or lipopolysaccharide (LPS) structure. Cc5 appeared to have several polysaccharidic structures, one being altered in Y1C12. The structure missing in Y1C12 could be purified by classical LPS purification procedures and labeled by tritiated palmitate, indicating that it is more likely to be an LPS structure than a capsule. Y1C12 bacteria were also more sensitive to phagocytosis by PMNs than wild-type bacteria. In conclusion, a polysaccharide structure, likely an LPS, protects C. canimorsus from deposition of the complement MAC and from efficient phagocytosis by PMNs.

SUBMITTER: Shin H

PROVIDER: S-EPMC2687352 | biostudies-literature | 2009 Jun

REPOSITORIES: biostudies-literature

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Resistance of Capnocytophaga canimorsus to killing by human complement and polymorphonuclear leukocytes.

Shin Hwain H Mally Manuela M Meyer Salome S Fiechter Chantal C Paroz Cécile C Zaehringer Ulrich U Cornelis Guy R GR

Infection and immunity 20090323 6

Capnocytophaga canimorsus is a bacterium of the canine oral flora known since 1976 to cause rare but severe septicemia and peripheral gangrene in patients that have been in contact with a dog. It was recently shown that these bacteria do not elicit an inflammatory response (H. Shin, M. Mally, M. Kuhn, C. Paroz, and G. R. Cornelis, J. Infect. Dis. 195:375-386, 2007). Here, we analyze their sensitivity to the innate immune system. Bacteria from the archetype strain Cc5 were highly resistant to kil ...[more]

PMID: 19307219

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Project description:Capnocytophaga canimorsus and Capnocytophaga cynodegmi are commensal bacteria in the oral cavities of dogs. Both are zoonotic pathogens that could infect humans via dog bites. C. canimorsus may cause life-threatening infections in humans, whereas C. cynodegmi infections tend to be milder and more localized. Capsular serovars A-C of C. canimorsus seem to be virulence-associated. Some of the C. canimorsus serovars described to date can also be detected in other Capnocytophaga species, including C. cynodegmi. The objective of this pilot study was to investigate the emergence of C. canimorsus and C. cynodegmi after birth in oral cavities of puppies and to evaluate the impact of the dam's Capnocytophaga spp. carrier status on the emergence. Ten litters, altogether 59 puppies, were included in the study. The puppies and their dams were sampled at five time points over seven weeks after whelping. Oral swab samples taken were investigated for the presence of C. canimorsus and C. cynodegmi by species-specific polymerase chain reaction (PCR), the specificity of which was verified by sequencing a selection of the PCR products. Samples that were positive in Capnocytophaga PCR reactions were also capsular-typed by PCR to gain more knowledge about the Capnocytophaga spp. present in the samples. Altogether 10.2% and 11.9% of puppies, or 20.0% and 30.0% of litters tested PCR-positive for C. canimorsus and C. cynodegmi, respectively. Capnocytophaga PCR-positive puppy samples were always positive for only C. cynodegmi or C. canimorsus, not both. Most Capnocytophaga PCR-positive puppies became positive at the age of 5 to 7 weeks. Only a minority (5/16) of the C. cynodegmi PCR-positive dog samples were positive in capsular typing PCR, whereas all C. canimorsus PCR-positive dog samples were negative in capsular typing PCR. For all Capnocytophaga PCR-positive puppies, their dam was positive for the same Capnocytophaga species. These results suggest that puppies become colonized by C. cynodegmi or C. canimorsus from their dams at the time of deciduous teeth eruption.

Dataset Information

Resistance of Capnocytophaga canimorsus to killing by human complement and polymorphonuclear leukocytes.

Publications

Resistance of Capnocytophaga canimorsus to killing by human complement and polymorphonuclear leukocytes.

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