Proteomic profiling of ovine serum by SELDI-TOF MS: optimisation, reproducibility and feasibility of biomarker...

The diagnosis of infectious diseases in animals may be enhanced by study of the serum proteome in which myriad components are influenced by physiological and pathological processes. Surface-enhanced laser desorption/ionisation time-of-flight mass spectrometry (SELDI-TOF MS) has the capacity to detect known and unknown immunologically relevant molecules in the serum proteome. Optimum combinations of ProteinChip array surfaces, energy absorbing molecules, sample dilutions and instrument settings were determined for spectral generation from whole ovine sera. The coefficient of variation for within and between chip mass/charge and peak intensity were <0.03% and <23%, respectively. There were minor alterations in spectra associated with storage of chips or machine drift. Clotting times of 30 min to 3h did not greatly alter protein spectra although storage of sera at -20 degrees C led to alterations. However, routinely collected serum samples stored at -20 degrees C were useful for identification of biomarkers associated with vaccination with a bacterial antigen. This information will inform future studies on serum proteome profiling in livestock, but independent assessments are recommended for each species.