Genome-Wide Transcriptional and Post-transcriptional Regulation of Innate Immune and Defense Responses of Bovine Mammary Gland to .

() is problematic for lactating mammals and public health. Understanding of mechanisms by which the hosts respond to severe invasion of remains elusive. In this study, the genome-wide expression of mRNAs and miRNAs in bovine mammary gland cells were interrogated at 24 h after intra-mammary infection (IMI) with high or low concentrations of . Compared to the negative control quarters, 194 highly-confident responsive genes were identified in the quarters with high concentration (10 cfu/mL) of , which were predominantly implicated in pathways and biological processes pertaining to innate immune system, such as cytokine-cytokine receptor interaction and inflammatory response. In contrast, only 21 highly-confident genes were significantly differentially expressed in face of low concentration (10 cfu/mL) of , which slightly perturbed the cell signaling and invoked corresponding responses like vasoconstriction, indicating limited perturbations and immunological evading. Additionally, the significant up-regulations of bta-mir-223 and bta-mir-21-3p were observed in the quarters infected by high concentration of . Network analysis suggested that the two miRNAs' pivotal roles in defending hosts against bacterial infection probably through inhibiting and . The significant down-regulation of was also observed in bovine mammary epithelial cells at 24 h post-infection of (10 cfu/mL) . Integrated analysis with QTL database further suggested 28 genes (e.g., , and ) as candidates of bovine mastitis. This study first systematically revealed transcriptional and post-transcriptional responses of bovine mammary gland cells to invading in a dosage-dependent pattern, and highlighted a complicated responsive mechanism in a network of miRNA-gene-pathway interplay.