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24, chemin de Borde Rouge –Auzeville – CS52627
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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

Role of Staphylococcus aureus extracellular vesicles in bovine mastitis: Tiny but mighty !

Staphylococcus aureus is a major pathogen responsible for bovine mastitis, the most common disease affecting dairy cattle. The economic impact of staphylococcal infection on dairy farms is mainly incurred by losses in milk production. We investigated the role of the extracellular vesicles (EVs) produced by S. aureus in the infectious process.

S. aureus naturally releases extracellular vesicles (EVs) during its growth. These EVs play an important role in the interactions between the producing bacteria and its host (mammal cells for example). They are also considered as nanocarriers that deliver virulence factors to the host tissues. Our objective was to investigate the role of EVs secreted by the strain S. aureus N305, which was isolated in a case of bovine mastitis and is now used as a model strain able to induce chronic mastitis in cows.

We found:

  • S. aureus strain N305 secretes nano-sized EVs in laboratory conditions
  • These EVS carry many virulence factors (10% of the vesicular proteome)
  • These EVs are not cytotoxic against bovine mammary epithelial cells in vitro
  • These EVs induce an immunostimulatory response in bovine mammary epithelial cells in vitro
  • These EVs induce inflammatory and a local host innate immune response in vivo in a S. aureus-induced mouse mastitis model



TEM monograph (left panel) and cryo-EM tomogram (right panel) of purified Staphylococcus aureus N305-secreted extracellular vesicles

Our study demonstrated that EVs produced by the mastitis strain S. aureus N305 induce an immunostimulatory response, both in bovine mammary epithelial cells in vitro and in a preclinical model of bovine mastitis. These findings provide both novel insights in S. aureus mastitis pathogenesis and innovative avenues to control mastitis in which EVs are proposed as potential candidates for the development of vaccines.





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Rocha Tartaglia N., Breyne K., Meyer E., Cauty C., Jardin J., Chrétien D., Dupont A., Demeyere K., Berkova N., Azevedo V., Guedon E., and Le Loir Y. 2018. Staphylococcus aureus Extracellular Vesicles Elicit an Immunostimulatory Response in vivo on the Murine Mammary Gland. Frontiers in Cellular and Infection Microbiology, 8 (article 277). DOI: 10.3389/fcimb.2018.00277


Éric Guédon •

Yves Le Loir •

>>> To Research Team