Transcripts and protein levels of CSN1S1 and CSN3 genes in dairy cattle mammary gland secretory tissue during chronic staphylococcal infection

Abstract

Abstract Our objective was to determine the influence of chronic coagulase-positive staphylococci (CoPS) or coagulase-negative staphylococci (CoNS) infection on the mRNA and protein levels of two main milk proteins responsible for cheese curd quantity and quality, alpha-S1-casein (CSN1S1) and kappa-casein (CSN3). Measurements were made in cow mammary parenchyma with a prevalence of secretory tissue (MGST). Samples of MGST were collected from the separate quarters and divided into CoPS, CoNS and bacteria-free (H) groups according to the microbiological status of the quarter milk. No differences in CSN1S1 and CSN3 mRNA level were found between groups, however, CSN1S1 protein level was significantly higher in the H group than the CoNS group, and CSN3 protein level was significantly higher in H than CoPS group. Hence, while the CSN1S1 and CSN3 genes appear to be constitutively expressed at the mRNA level in dairy cow MGST during mastitis, CoNS infection negatively affected CSN1S1 protein level, and CoPS infection negatively affected CSN3 protein level. The lack of change at the mRNA level suggests that staphylococcal infection may affect the post-transcriptional or post-translational modifications.