PRNP and infection: The most widely accepted hypothesis holds that the disease-causing event for naturally acquired TSEs is a peripheral infection with an "infectious" protease-resistant isoform of the prion protein (PrP) that initiates the conversion of the host's cellular PrP into a pathologically misfolded and/or aggregated form, referred to as PrPSc [2-4] or PrPTSE [5].