Synthetic scrapie infectivity: interaction between recombinant PrP and scrapie brain-derived RNA.

The key molecular event in human cerebral proteinopathies, which include Alzheimer's, Parkinson's and Huntington's diseases, is the structural conversion of a specific host protein into a β-sheet-rich conformer. With regards to this common mechanism, it appears difficult to explain the outstanding infectious properties attributed to PrPSc, the hallmark of another intriguing family of cerebral proteinopathies known as transmissible spongiform encephalopathies (TSE) or prion diseases. The infectious PrPSc or "prion" is thought to be composed solely of a misfolded form of the otherwise harmless cellular prion protein (PrPc). To gain insight into this unique situation, we used the 263K scrapie hamster model to search for a putative PrPSc-associated factor that contributes to the infectivity of PrPSc amyloid. In a rigorously controlled set of experiments that included several bioassays, we showed that originally innocuous recombinant prion protein (recPrP) equivalent to PrPc is capable of initiating prion dise...