Staphylococcus aureus seroproteomes discriminate ruminant isolates causing mild or severe mastitis
Résumé
Background and aims. Staphylococcus aureus is a major cause of mastitis in ruminants where symptoms range from subclinical to gangrenous mastitis. S. aureus factors or host-factors contributing to the different outcomes are not completely elucidated. This study aimed to the identification of staphylococcal immunoreactive proteins commonly or differentially produced during infections of variable severity. Methods. Experimental mastitis were induced on primiparous ewes using two S. aureus strains, isolated from gangrenous (strain O11) or subclinical (strain O46) mastitis. SERological Proteome Analysis (SERPA) was used to define core and accessory seroproteomes. Results. Strains induced drastically distinct clinical symptoms in ewe experimental mastitis. Notably, they reproduced mild (O46) or severe (O11) mastitis. SERPA allowed the identification of 89 immunoreactive proteins, of which only 52 (58.4%) were previously identified as immunogenic proteins in other staphylococcal infections. Among the 89 proteins identified, 74 appear to constitute the core seroproteome. Among the 15 remaining proteins defining the accessory seroproteome, 12 were specific for strain O11, 3 were specific for O46. Conclusion. We report here for the first time the identification of staphylococcal immunogenic proteins common or specific to S. aureus strains responsible for mild or severe mastitis. These findings open avenues in S. aureus mastitis studies as some of these proteins, expressed in vivo, are likely to account for the success of S. aureus as a pathogen of the ruminant mammary gland.