To characterise in sheep the bovine spongiform encephalopathy agent (BSE) responsible for variant Creutzfeldt-Jakob disease in human beings, three ewes, presenting either a susceptible (2-ARQ/ARQ) or a resistant (1-ARR/ARR) genotype toward scrapie, were infected with a French BSE case. The research of abnormal prion protein (PrPsc) accumulating sites revealed traces of PrPsc in ARR/ARR sheep but did not distinguish BSE agent in ARQ/ARQ sheep from natural scrapie cases. The BSE agent was finally identified in these ewes by analysing protease cleavage sites of PrPsc and comparing, in mice infected with BSE, ovine-BSE and scrapie, the neuro-anatomical distribution of PrPsc deposits which was discriminant. Thus, as some properties of the BSE agent are maintained in sheep, it may be possible to identify this agent in sheep flocks using theses approaches.
