Understanding transmission of the prion diseases

The transmissible spongiform encephalopathies (TSEs) or prion diseases are a group of fatal neurodegenerative diseases that are also infectious. It has been proposed that the infectious agent is a form of the PrP protein (PrP super(Sc)) that is conformationally different from the normal cellular form, PrP super(C). Conversion of PrP super(C) to the protease-resistant PrP super(Sc) during the infectious process results in a change in protein structure from predominantly alpha -helical to a beta -sheet form. The prion hypothesis predicts PrP super(Sc) can propagate its own conversion by acting as a template or seed that allows further conversion of PrP super(C) to PrP super(Sc). Alternative hypotheses view the conversion of PrP super(C) to PrP super(Sc) as a consequence of a disease process in which PrP super(C) might act as a receptor for the infectious agent.