PRNP and scrapie: In this study, to evaluate the role of residues 91–106 of PrPC in prion pathogenesis, Tg(PrP∆91–106)/Prnp0/0 mice expressing mouse PrP lacking residues 91–106 or PrP∆91–106, on the Prnp0/0 background were generated and intracerebrally inoculated with mouse-adapted scrapie prions of RML and 22L, mouse-adapted human prions of FK-1 and mouse-adapted BSE prions.