Proteomic Analysis of Milk Whey from Buffaloes Diagnosed with Subclinical Mastitis

To understand the mechanisms and effects of mastitis on the mammary gland, proteomic approaches have been applied to examine the composition of milk from affected animals. The aim of this study was to investigate the changes in the whey protein (or milk serum protein) profile from buffaloes with subclinical mastitis relative to unaffected animals. A total of 16 milk samples were collected from Murrah buffaloes, which comprised eight animals with and eight animals without subclinical mastitis. To determine which animals were or were not with subclinical mastitis we used an indirect method (California Mastitis Test: (+) weakly positive, (++) positive, (+++) strongly positive, and (-) negative) and a direct method (Somatic Cell Count: ≤ 101 × 10³ cells/mL (without mastitis) and ≥ 2310 × 10³ cells/mL (mastitis). Two technical replicates of milk whey samples were analyzed for each animal using an LTQ Orbitrap ELITE mass spectrometer coupled to a nano-flow chromatography system (LC-MS/MS). Data obtained were processed using the Computational Proteomics Analysis System (CPAS). The annotated protein database for Bubalus bubalis available on NCBI was used in the analysis. Spectral counts were used to quantify the relative abundance of individual proteins. Our preliminary results suggest that 1044 proteins were identified in the 32 analyzed samples, of which, 493 were found only in the samples from cows with mastitis. The identification of differentially expressed proteins will help in the development of biomarkers for the early detection of this economically important disease in dairy buffaloes.

Acknowledgments: São Paulo Research Foundation (FAPESP) #2016/10526-8, #2014/19321-4 and #2014/25309-7.