Changes in Serum Protein Profiles of Chickens with Tibial Dyschondroplasia

Differences in serum protein profiles were analyzed to identify possible biomarkers associated with a poultry leg problem named tibial dyschondroplasia (TD) that can lead to lameness. A bead-based affinity matrix (ProteoMiner TM ) containing a combinatorial library of hexapeptides was used to deplete high abundant proteins and enrich the less abundant ones to compare between the sera of six-week old normal and TD affected chickens. Equal amounts of proteins in ProteoMiner depleted serum from control and TD-affected birds were subject to 2D gel electrophoresis, image analysis, and compared to identify the differentially expressed protein spots. The protein spots were characterized using in-gel trypsin digestion followed by mass spectrometry (MS). Of 46 matched protein spots in the gels, 33 were identified by peptide mass finger printing (PMF) and tandem mass spectrometry (MS/MS). Eight spots corresponding to immunoglobulins (Ig) were up-regulated in birds with TD and two spots down regulated. The up-regulated Ig proteins belonged to IgM and IgY(IgG) classes indicated by the identification of ‘mu’ chain and Fc fragment associated peptides respectively. Enzyme linked immunosorbent assay corroborated an increase in serum IgM levels but not IgG. Although the significance of the increase in IgM proteins in the serum of TD-affected chickens is not understood, it is likely that IgM plays some role in the removal of apoptotic chondrocytes which abound within TD lesions.