Immuno-Detection of C3a, a C3 Complement Activated Product in Mastitis Milk, a Potential Diagnostic Marker

The sub-clinical form of mastitis is difficult to detect and causes huge economic loss to the dairy industry. It has become a threat to public health at large, thus there is a need for definite diagnosis of the disease. Therefore, this study was undertaken to identify the novel diagnostic marker for the detection of the sub-clinical form of mastitis. Two-dimensional gel analysis of the whey protein fraction of normal and mastitis milk samples revealed the presence of proteose peptone component 3 precursor, Trypsin precursor, complement component-C3, Ig heavy chain precursors and a C-type lectin domain as differentially expressed protein during the early stage of mastitis. Of these proteins identified, complement component-C3 was tested for its diagnostic potential. Western blot analysis of the milk whey of sub-clinical mastitis cases (M+, M++ & M+++) identified the accumulation of C3a, an activated product of complement component-C3. Further, the hemolytic activity of the above milk whey samples positively correlated with the somatic cell count. As C3a is already reported as an anaphylotoxic agent, it chemo tactically attracts lymphocytes at the site of inflammation, the detection of which in the milk whey can be of diagnostic importance for sub-clinical mastitis.