Molecular analysis of ovine prion protein identifies similarities between BSE and an experimental isolate of natural scrapie, CH1641

New variant Creutzfeldt-Jakob disease (vCJD) and bovine spongiform encephal opathy (BSE) are caused by the same strain of pathogen and, as sheep can de velop experimental BSE, this has raised concern that humans may be at risk from eating mutton if BSE has naturally transmitted to sheep. Biochemical t yping of abnormal prion proteins (PrPSc) has been suggested to detect BSE i n sheep. Although this approach is ingenuous, we can now report biochemical evidence of strain variation in contemporary and archival brain tissue fro m cases of experimental BSE or experimental and natural scrapie in sheep. I nterestingly, we found at least one isolate of natural scrapie (CH1641)with a very similar, but not identical, PrPSc profile to BSE but which differs from BSE in its transmission characteristics to mice.