Plasma proteomic profiles of healthy and mastitic cows – host responses to bovine mastitis

Abstract. Mastitis is the most common disease in dairy cows and has resulted in a tremendous economic loss in dairy industry. In the present study, differentially expressed proteins (DEP) were identified among healthy, moderate and severe mastitic cows by proteomic profiling. The health status of cows was closely determined by the somatic cell count (SCC). Differentially expressed proteins were resolved using the two-dimensional gel electrophoresis (2-DE) with the pH 4–7 non-linear DryStrips. Subsequently, 8 protein spots, which altered more than 3-fold, were isolated and identified with the matrix-assisted laser desorption/ionisation-time of flight mass spectrometry (MALDI TOF/TOF MS). The identified spots were split into four proteins: α-2-HS-glycoprotein, serum albumin, transthyretin (TTR) and haptoglobin, respectively. Compared with the healthy cows, the expression of haptoglobin was up-regulated in mastitic cows, and the others were down-regulated. Moreover, the proteomic data were consistent with the results of Western blot. All of the identified DEPs were acute phase proteins, which acted together and represented the consequence of serial cascades after mastitic infection. More importantly, the α-2-HS-glycoprotein was novel identified corresponding to the bovine mastitis in Chinese Holstein dairy cows. Taken together, our results indicate that the host responses may play an important role in the pathogenesis of mastitis and provide the potential diagnostic indicator of the underlying mastitis in dairy cows.