Immune response variations and intestinal flora changes in mastitis induced by three Streptococcus uberis strains.

Streptococcus uberis is a common cause of mastitis. The pathogenicity among different strains of S. uberis and the resultant host immune responses remain to be elucidated. Herein, we document immune responses among 3 strains of S. uberis, and preliminary explore whether and how intestinal immunity play a role in host anti-infection processes. Mice have been proved to be effective experimental animals for bovine mastitis, so utilizing a mouse intramammary infection model, we assay immune responses and gut flora changes of 3 S. uberis strains by histopathologic examination, RT-PCR, Western blot and 16s rDNA sequencing. We find that the immune responses among the 3 sequence type (ST) S. uberis strains may be linked to the hasA/B and lbp virulence genes, and the beta diversity of the intestinal may be independent of the ST type of S. uberis. Twenty phyla and 30 genera of intestinal flora are identified, Verrucomicrobia and Akkermansia being the most prominent phylum and genus respectively. These bacteria have strong anti-inflammatory and protective effects against S. uberis challenge. These datas provide a foundation for further studies to elucidate gut flora function and exploration of therapeutic targets for mastitis. This article is protected by copyright. All rights reserved.