High sensitivity detection of the glial fibrillary acidic protein as indicator for TSE risk material in meat products using an immuno-PCR

The emergence of prion diseases in cattle during the bovine spongiform encephalopathy (BSE) epidemic and the transmission to humans causing variant Creutzfeldt-Jakob disease by consume of BSE-contaminated meat has focused attention on the use of tissues from the central nervous system (CNS) in food. To avoid food contamination, it is regulated by law that specified risk material has to be removed from food chains. Detection of well-expressed CNS indicator proteins such as the glial fibrillary acidic protein (GFAP) assumes ail important role in detection of food contamination; however, the sensitivity of detection performed on basis of ELISAs is limited. Consequently, there is an urgent need for high-sensitivity detection methods. We describe the development of an immuno-PCR assay with enhancement of the immunoreaction by amplification of a DNA fragment linked to the antigen-antibody complex. This immuno-PCR assay shows enhanced sensitivity in GFAP detection of at least two orders of magnitude compared to the ELISA technique carried out under identical conditions. The immuno-PCR proves to be a suitable tool for the high-sensitivity detection of marker proteins in food imported by food chain processes. It is applicable for use by food and veterinary facilities, and institutes involved in food monitoring.