Location of Staphylococcus aureus Within the Experimentally Infected Bovine Udder and the Expression of Capsular Polysaccharide Type 5 in Situ

Hensen, Selma; Pavičić, M. J. A. M. P.; Lohuis, J.A.C.M.; Hoog, J.A.M. de; Poutrel, B.

doi:10.3168/jds.s0022-0302(00)75073-9

Cited by 76 publications

(76 citation statements)

References 32 publications

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“…S. aureus capsule production might be different in vivo and in vitro and is possibly enhanced by growth in milk (18). CP expression has been demonstrated in situ in experimental bovine mastitis (10), and further studies are needed in order to examine the effects of variations in capsule production on host defense mechanisms.…”

Section: Discussionmentioning

confidence: 99%

Staphylococcus aureus Capsular Polysaccharide Types 5 and 8 Reduce Killing by Bovine Neutrophils In Vitro

2005

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Isogenic variants of Staphylococcus aureus strain Reynolds expressing either no capsule or capsular polysaccharide (CP) type 5 (CP5) or type 8 (CP8) were used to assess the effect of CP on bacterial killing and the respiratory burst of bovine neutrophils. The effects of antisera specific for CP5 and CP8 were also evaluated. The killing of live bacteria by isolated neutrophils was quantified in a bactericidal assay, while the respiratory burst after stimulation with live bacteria in whole blood was measured by flow cytometry. The expression of a CP5 or CP8 capsule protected the bacteria from being killed by bovine neutrophils in vitro (P < 0.001), and the capsule-expressing variants did not stimulate respiratory burst activity in calf whole blood. The addition of serotype-specific antisera increased the killing of the capsule-expressing bacteria and enhanced their stimulating effect in the respiratory burst assay (P < 0.01). When the S. aureus variants were grown under conditions known not to promote capsule expression, there were no significant differences between them. The present study demonstrates that the expression of S. aureus CP5 or CP8 confers resistance to opsonophagocytic killing and prevents the bacteria from inducing respiratory burst of bovine neutrophils in vitro and that these effects can be reversed by the addition of serotype-specific antisera.Many bacterial species have well-characterized capsules which are important virulence factors that potentiate infections (20). In addition to being a major human pathogen, Staphylococcus aureus is the cause of a variety of infections in animals. Most important is mastitis of dairy cows, which compromises animal welfare and causes large economic losses for the dairy industry. S. aureus produces various surface polysaccharides (18,19,22,40), and most strains express capsular polysaccharides (CPs) in vivo or under defined culture conditions (24). Although at least 11 serotypes based on CPs have been proposed, only four CPs (CP1, CP2, CP5, and CP8) have been chemically characterized (15).Phagocytosis and killing by neutrophil granulocytes play a key role in defense against S. aureus infections. CP1 and CP2 have been shown to have antiphagocytic properties (9,17,25,41), but such heavily capsulated strains are rarely isolated clinically (2,31,43). Most clinical isolates from both human and bovine infections produce either CP5 or CP8, although considerable geographic variations exist in the prevalence of these types in bovine isolates (26,32,37).The relatively small amount of CP produced by serotype 5 and 8 strains has made it difficult to define the role of these capsules in virulence. However, the antiphagocytic properties of the S. aureus CP5 capsule, as measured in in vitro opsonophagocytic killing assays, have been shown to play an important role in the pathogenesis of S. aureus infections, most likely by allowing the organism to resist uptake and killing by phagocytes (21, 35).Opsonization is of major importance for effective phagocytosis of most bacterial ...

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Section: Discussionmentioning

confidence: 99%

Staphylococcus aureus Capsular Polysaccharide Types 5 and 8 Reduce Killing by Bovine Neutrophils In Vitro

2005

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“…The bovine strain RF122 was isolated from clinical mastitis and corresponds to a predominant and widespread clone associated with bovine mastitis that has been completely sequenced. The three other bovine strains studied were isolated from subclinical mastitis and were chosen because they reproducibly induced subclinical mastitis in experimental udder infections in cows (3,17,36, and F. Gilbert, IASP-INRA Tours, personal communication). Ovine and caprine strains were isolated from clinical mastitis, the predominant form of the disease in those animals.…”

Section: Methodsmentioning

confidence: 99%

Genome-Wide Analysis of Ruminant Staphylococcus aureus Reveals Diversification of the Core Genome

et al. 2008

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Staphylococcus aureus causes disease in humans and a wide array of animals. Of note, S. aureus mastitis of ruminants, including cows, sheep, and goats, results in major economic losses worldwide. Extensive variation in genome content exists among S. aureus pathogenic clones. However, the genomic variation among S. aureus strains infecting different animal species has not been well examined. To investigate variation in the genome content of human and ruminant S. aureus, we carried out whole-genome PCR scanning (WGPS), comparative genomic hybridizations (CGH), and the directed DNA sequence analysis of strains of human, bovine, ovine, and caprine origin. Extensive variation in genome content was discovered, including host-and ruminantspecific genetic loci. Ovine and caprine strains were genetically allied, whereas bovine strains were heterogeneous in gene content. As expected, mobile genetic elements such as pathogenicity islands and bacteriophages contributed to the variation in genome content between strains. However, differences specific for ruminant strains were restricted to regions of the conserved core genome, which contained allelic variation in genes encoding proteins of known and unknown function. Many of these proteins are predicted to be exported and could play a role in host-pathogen interactions. The genomic regions of difference identified by the wholegenome approaches adopted in the current study represent excellent targets for studies of the molecular basis of S. aureus host adaptation.

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“…Distribution of genotypes among isolates originated in different geographical areas is shown in Table 1 (4,7); however associations in these latter cases were established with patterns including several rather than individual genes (4).…”

Section: Capsular Polysaccharides In Vitro Expression Does Notmentioning

confidence: 99%

Genotypic and phenotypic detection of capsular polysaccharides in Staphylococcus aureus isolated from bovine intramammary infections in Argentina

Camussone¹,

Rejf²,

Pujato³

et al. 2012

Braz. J. Microbiol.

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Location of Staphylococcus aureus Within the Experimentally Infected Bovine Udder and the Expression of Capsular Polysaccharide Type 5 in Situ

Cited by 76 publications

References 32 publications

Staphylococcus aureus Capsular Polysaccharide Types 5 and 8 Reduce Killing by Bovine Neutrophils In Vitro

Staphylococcus aureus Capsular Polysaccharide Types 5 and 8 Reduce Killing by Bovine Neutrophils In Vitro

Genome-Wide Analysis of Ruminant Staphylococcus aureus Reveals Diversification of the Core Genome

Genotypic and phenotypic detection of capsular polysaccharides in Staphylococcus aureus isolated from bovine intramammary infections in Argentina

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