PRNP and Creutzfeldt Jacob disease: The production of extremely high levels of FU-CJD infectivity in SEP cells with ∼10x normal levels of PrP was unexpected because Tga20 mice with comparably high PrP levels have not shown increased titers compared to wt mice with 1x PrP; this is true for diverse agents including Chandler (RML) scrapie, FU-CJD, and kuru agents in Tga20 mice [3], [23], [30].