Recent Advancement in 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. Within the mastitis condition, sub-clinical mastitis is of greater importance because of its
adverse effect on milk production and quality and its impact on public health. 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 subclinical
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. Therefore, use of complement component may
be considered for the diagnosis of mastitis as it was proved to be directly related to the elimination of
microorganisms that are being activated during infection and the activated products such as C3a are
detected in the milk, as demonstrated in this study.