Detection of CNS and PrPSc in meat products

Several methods for the detection of tissues of the central nervous system (CNS) in meat products have been developed and partly validated for use in official food control as pertaining to human BSE-exposure risk. So far, however, methods for the detection of abnormal prion protein (PrPSc) were not evaluated for their potential applicability to the matrix of heat treated meat products. We developed a micro technological procedure for the preparation of meat products suitable for high security laboratories as masses were 6 to 8 orders of magnitude lower than in conventional meat technology. Thus it was possible to produce standard micro sausages containing defined amounts of bovine BSE-positive brain. This material showed all characteristics of normal meat products and a homogeneous distribution of brain as indicated by NSE and GFAP western immunoblotting and GFAP immunometric analyses. Using a commercially available and certified immunometric assay for detection of PrPSc in untreated brain it was possible to detect BSE-positive CNS down to a content of 0.25% in heat treated meat products. We found a high correlation between PrPSc OD-values and CNS content and linearity up to 10% CNS. In 30 samples of retail meat products no sample transgressed the official cut off value for untreated bovine brain. Further studies are needed to show whether an increase of sensitivity in PrPSc detection from the meat product matrix is possible, in particular by optimisation of the extraction procedure.