PRNP and scrapie: Although its physiological function isstill largely unknown, PrP protein is unequivocally associated to the onset ofa family of diseases named transmissible spongiform encephalopathies (TSE) [3] by a mechanism involving the conversion of the cellular form,PrPC, into an insoluble (scrapie) variant, PrPSc, which is deemed to alsoretain an intrinsic infectivity [4].