Molecular basis of virulence in Staphylococcus aureus mastitis

Caroline Le Maréchal (1, 2) , Nubia Seyffert (1, 3) , Julien Jardin (1) , David Hernandez (4) , Gwénaël Jan (1) , Lucie Rault (1) , Vasco Azevedo (3) , Patrice François (4) , Jacques Schrenzel (4) , Maarten van de Guchte (5) , Sergine Even (1) , Nadia Berkova (1) , Richard Thiéry (6) , J.R. Fitzgerald (7) , Eric Vautor (6) , Yves Le Loir (1)

1 STLO - Science et Technologie du Lait et de l'Oeuf
2 Laboratoire de Sophia-Antipolis, Unité pathologie des ruminants
3 ICB - Instituto de Ciencias Biologicas [Minas Gerais]
4 Genomic Research Laboratory, Service of infectious diseases
5 MICALIS - MICrobiologie de l'ALImentation au Service de la Santé
6 Laboratoire de Sophia-Antipolis, Unité pathologique des ruminants
7 The Roslin Institute and Centre for Infectious Diseases, Royal dick school of veterinary studies

Background: S. aureus is one of the main pathogens involved in ruminant mastitis worldwide. The severity of staphylococcal infection is highly variable, ranging from subclinical to gangrenous mastitis. This work represents an in-depth characterization of S. aureus mastitis isolates to identify bacterial factors involved in severity of mastitis infection. Methodology/Principal Findings: We employed genomic, transcriptomic and proteomic approaches to comprehensively compare two clonally related S. aureus strains that reproducibly induce severe (strain O11) and milder (strain O46) mastitis in ewes. Variation in the content of mobile genetic elements, iron acquisition and metabolism, transcriptional regulation and exoprotein production was observed. In particular, O11 produced relatively high levels of exoproteins, including toxins and proteases known to be important in virulence. A characteristic we observed in other S. aureus strains isolated from clinical mastitis cases. Conclusions/Significance: Our data are consistent with a dose-dependant role of some staphylococcal factors in the hypervirulence of strains isolated from severemastitis. Mobile genetic elements, transcriptional regulators, exoproteins and iron acquisition pathways constitute good targets for further research to define the underlying mechanisms of mastitis severity.

Mots clés: staphylococcus aureus; mammite; inflammation; mastitis; mamary gland; multidisciplinary sciences; science and technology

Domaines: Biologie cellulaire

Caroline Le Maréchal, Nubia Seyffert, Julien Jardin, David Hernandez, Gwénaël Jan, et al.. Molecular basis of virulence in Staphylococcus aureus mastitis. PLoS ONE, 2011, 6 (11), ⟨10.1371/journal.pone.0027354⟩. ⟨hal-01189501⟩