Immune response of Staphylococcus aureus strains in a mouse mastitis model is linked to adaptive capacity and genotypic profiles

PEREYRA, ELIZABET A.L.; SACCO, SOFIA CLARA; DURÉ ANDREA BELÉN; BARAVALLE, CELINA; RENNA, MARÍA SOL; ANDREOTTI, CAROLINA S.; MONECKE, STEFAN; CALVINHO, LUIS F.; DALLARD, BIBIANA E.

VETERINARY MICROBIOLOGY

ELSEVIER SCIENCE BV

Año: 2017

0378-1135

Staphylococcus aureus is one of the most frequently isolated major pathogens from intramammary infections (IMI) worldwide. The mechanisms by which S. aureus IMI are established and maintained in dairy cows involve both bacterial escape strategies and modulation of the host immune response. Moreover, it was shown that different S. aureusstrains have varying effects on the immune response. The aim of this study was to investigatethe immune response in a mouse mastitis model of two S. aureus strains isolated from bovineIMI with different clinical manifestation (persistent-P or non-persistent-NP), phenotypic andgenotypic profile. Both strains were capable of establishing an IMI after 264 h post inoculation(pi). Strain A (NP) showed a more aggressive behaviour than strain B (P) at early stages of IMI,while strain B multiplied initially at a lower rate but increased its replication capacity from 120h pi to the end of the study (264 h pi). Strain A triggered a stronger initial inflammatoryresponse compared with strain B inducing higher gene and protein expression of TLR2, NF-©§Bactivation and higher gene expression of IL-1¥á at initial stage of IMI (6 to 12 h pi) but inducingextensive mammary tissue damage. Immune cells response was different for each S. aureusstrain throughout the course of infection, showing mammary glands inoculated with strain Agreater initial immune cells stimulation compared with strain B and then a second immune cellsstimulation (from 120 to 264 h pi) represented by monocytes-macrophages, T and Blymphocytes, mainly stimulated by strain B, consistent with inflammatory process becomingchronic. Strain-specific pathogenicity observed underscores the importance of pathogen factors in the progression of the infectious process. These results contribute to increase the availableinformation on host-pathogen interaction and point out for the need of further research toexpand the knowledge about these interactions for developing new strategies to intervene in theIMI progress.