Suitability of Antigens PGP 9.5 and Neurofilament Light as Marker Proteins for Detection of Neuronal Tissue in Processed Meat Products

The enforcement of rules for food labeling and quantitative ingredient declaration presupposes appropriate test systems. Additionally, central nervous system (CNS) tissue of ruminants is classified as specified risk material for the transmission of prion diseases, and its detection is needed to support the specified risk material ban. Existing antibody-based test systems are hampered by relatively high limits of detection and susceptibility to food processing conditions. For that reason we tested a broad panel of commercially available monoclonal antibodies to identify marker antigens appropriate for the development of a sensitive test system. Western blot analysis using organ-specific samples from cow, pig, and chicken and differently processed meat products containing defined amounts of CNS tissue revealed neurofilament light (NF-L) and protein gene product 9.5 (PGP 9.5) as suitable antigens for the organ-specific and sensitive detection of porcine and bovine CNS tissue. None of the tested PGP 9.5 antibodies displayed cross-reactivity to chicken tissues. Both antigens could be detected in moderately (F10(121.1) = 0.84) and strongly (F10(121.1) = 4.01) heated processed meat products containing 5% (NF-L) or 0.2% (PGP 9.5) CNS tissue, respectively. Further, two monoclonal antibodies (clones 13C4 and 31A3) directed against PGP 9.5 were used for the development of a sandwich enzyme-linked immunosorbent assay. The limits of detection of the enzyme-linked immunosorbent assay were approximately 2% added CNS tissue in fresh processed meat products and approximately 0.5% for strongly heated processed meat products (F10(121.1) = 4.01). In conclusion this test system constitutes a valuable supplementation to existing procedures, which could improve enforcement of food safety regulations.