Abstract
Prions, the agents of transmissible spongiform encephalopathies, require the expression of a cellular homologue (PrPc) to propagate disease. The last is converted into an abnormal insoluble form, PrPsc, which a possible gain of neurotoxic activity. Since clinical manifestations may occur either before or without PrPsc deposits, it has been suggested that loss-of PrPc function may concur f…