Validation of a Western immunoblotting procedure for bovine PrPSc detection and its use as a rapid surveillance method for the diagnosis of bovine spongiform encephalopathy (BSE)

In this report we document the results of several independent studies testi ng the sensitivity, specificity and reliability of the Prionics Western blo tting (PWB) procedure to detect bovine and ovine disease-specific, protease -resistant prion protein (PrPSc). Validation of the technique was obtained by blind analysis of samples from cattle affected with bovine spongiform en cephalopathy (BSE), clinically normal animals or cattle with neurological d iseases unrelated to BSE. Overall, very high sensitivity, specificity and r eliability was observed. It became clear that sampling of the correct brain region and the method used for protein extraction are important factors fo r correct diagnosis. Furthermore, we tested the usefulness of the PWB techn ique as an instrument for surveillance purposes. We analyzed animals from a culling scheme as well as older animals from abattoirs to determine the nu mber of subclinical BSE cases detectable by histopathological examination, immunohistochemistry for PrPSc and PWB. In both studies, BSE-affected anima ls with no overt clinical symptoms were detected. These results demonstrate the usefulness of the PWB procedure in surveillance systems serving as a r apid diagnostic tool to identify animals subclinically infected with BSE.