Diagnostic markers for diseases: SELDI-TOF profiling of pig sera for PRRS

Porcine reproductive and respiratory syndrome (PRRS) is a highly infectious viral disease causing severe losses to the pig industry. Most weaning piglets are likely to be exposed to the infection and show at least asymptomatic PRRS viremia strongly related to productive performance. The aims of this study were to set up experimental conditions for pig sera proteomic profiling and to identify biomarkers that differentiate weaning asymptomatic piglets positive to PRRS viremia from negative controls (PCR tested) with potential predictive value for the subsequent occurrence of clinical PRRS. Protein profiles were generated by SELDI-TOF MS using the Bio-Rad Chips WCX, IMAC30 and H50. The discovery phase revealed that a consistent number of highly significant protein peaks can be detected by the WCX and IMAC30 surfaces; however none of these peaks were statistically confirmed by the subsequent validation phase, highlighting that serum concentration of the contaminant and most abundant proteins is a crucial parameterfor SELDI-TOF MS studies. Current protocols are being furtheroptimized and adapted to pig sera to reduce the unfavourable effects of the most abundant proteins and to increase the number of potential detectable biomarkers. Furthermore, proteomic fingerprint profiling has been shown to be a promising diagnostic tool that, in the future, may be useful to provide also insights into the mechanisms of early viral infection in vivo.