COMPARISON OF SCRAPIE-ASSOCIATED FIBRIL DETECTION AND WESTERN IMMUNOBLOTTING FOR THE DIAGNOSIS OF NATURAL OVINE SCRAPIE

Detergent- and proteinase K-treated extracts of grey matter were prepa red from four regions of the brains of 106 sheep with scrapie, diagnos ed clinically and by the demonstration of spongiform encephalopathy. T he extracts were examined by electron microscopy for the presence of s crapie-associated fibrils and by Western immunoblotting for the diseas e-specific abnormal prion protein (PrPSc). As a diagnostic method, Wes tern immunoblotting proved to be more sensitive than electron microsco py, the detection rates in the 106 sheep being 97 and 91% respectively (medulla), 99 and 76% (cerebellum), 95 and 88% (frontal cerebral cort ex) and 93 and 61% (occipital cerebral cortex). Neither fibrils nor Pr PSc could be detected in comparable brain extracts from 25 control she ep which had shown no clinical or histopathological evidence of scrapi e. (C) British Crown copyright 1998.