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Dernière mise à jour : Mai 2018

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Internet de l'unité STLO Science et Technologie du Lait et de l'Oeuf

STLO Research Unit

Exfoliative toxin E, a new Staphylococcus aureus virulence factor with host-specific activity

Microbio-R24
Staphylococcus aureus is a major pathogen which represents a worldwide concern in both human- and animal- health. Human nose and skin are its primary ecological niches, but some S. aureus clones have evolved and adapted to other hosts, such as bovine, ovine or caprine ruminants. Here, we investigated the host-specific activity of a new type toxin, the exfoliative toxin ETE.

S. aureus produces numerous virulence factors, some of which are secreted toxins with potent deleterious activity on the host tissues, including the Exfoliative toxins (ET). These ETs specifically recognize and hydrolyze the desmoglein 1 protein (Dsg1), causing a dissociation of keratinocytes in human and animal skin, which results in the “staphylococcal scalded skin” syndrome. To date, three different ET serotypes (ETA, ETB and ETD) are described. We discovered a new type of Exfoliative toxin (ETE), which is specifically associated to S. aureus strains isolated from ovine host.

In this work, we characterized ETE activity and specificity:

  • ETE amino acid sequence is different from those of the already described ETs,
  • ETE caused exfoliation in vivo on neonate mice,
  • ETE is active in vitro on the human, murine, swine, ovine and caprine desmoglein proteins Dsg,
  • ETE is not active on canine or bovine desmoglein proteins Dsg1.

 

Effect of exfoliative toxin on epithelial cells
image ETE

The new  exfoliative toxin ETE produced by Staphylococcus aureus
causes microscopic blisters (indicated by the arrow)in neonatal mice

Molecular modelling revealed a correlation between
the preferred orientation of ETE docking on its Dsg1
cleavage site and species-specific cleavage activity

 
 
ETE is thus a new S. aureus virulence factor frequently associated with ovine S. aureus isolates. It is also a new example of host specialization in S. aureus. The ete gene is found in S. aureus strains associated with mild mastitis in ewes. It may therefore be a marker of S. aureus virulence in ewe mastitis. Whether and how it provides selective advantages for S. aureus colonization and persistence in the udder still needs to be clarified.

 

FiletGris

 

Collaborations

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Imanishi I., A. Nicolas, A.-C. Barbosa Caetano, T. L. de Paula Castro, N. Rocha Tartaglia, R. Mariutti, E. Guédon, S. Even, N. Berkova, R. K. Arni, N. Seyffert, V. Azevedo, K. Nishifuji and Y. Le Loir. 2019. Exfoliative toxin E, a new Staphylococcus aureus virulence factor with host-specific activity. Scientific Reports 9:16336. DOI: 10.1038/s41598-019-52777-3 

Contacts

Yves Le Loir • yves.Le-loir@inrae.fr

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