Assessment and Characterization of Haptoglobin Isotype in Milk of Mastitis-Affected Cows

Haptoglobin is a major acute phase protein in bovines and reportedly increases in serum and milk
whey during mastitis, highlighting its potential as a diagnostic biomarker. Since haptoglobin is known
to undergo tissue specific glycosylation resulting in different isoforms, this study was undertaken to
characterize the isoforms of haptoglobin. Milk whey fraction and serum obtained from animals with or
without clinical mastitis in Puducherry, India, were subjected to SDS-PAGE followed by western blot
and immuno-detection of haptoglobin protein. All subunits (, α1 and α2) of haptoglobin protein were
detected in serum sample obtained from clinical cases. However, only the -subunit was detected in
milk whey fraction obtained from the respective animals. Similar results were observed with milk whey
fractions from subclinical cases indicating difference in isoform of haptoglobin detected in milk whey
from serum. This was further supported by RT-PCR (Reverse Transcription Polymerase Chain
Reaction) analysis of haptoglobin gene (Hp) confirming the tissue specific origin of haptoglobin.