Classic Scrapie in Sheep with the ARR/ARR Prion Genotype in Germany and France

摘要

In the past, natural scrapie and bovine spongiform en-cephalopathy (BSE) infections have essentially not been diagnosed in sheep homozygous for the A136R154R171hap-lotype of the prion protein. This genotype was therefore assumed to confer resistance to BSE and classic scrapie under natural exposure conditions. Hence, to exclude pri-ons from the human food chain, massive breeding efforts have been undertaken in the European Union to amplify this gene. We report the identifi cation of 2 natural scrapie cases in ARR/ARR sheep that have biochemical and transmission characteristics similar to cases of classic scrapie, although the abnormally folded prion protein (PrPSc) was associated with a lower proteinase-K resistance. PrPScwas clearly dis-tinct from BSE prions passaged in sheep and from atypical scrapie prions. These fi ndings strongly support the idea that scrapie prions are a mosaic of agents, which harbor differ-ent biologic properties, rather than a unique entity