PRNP and scrapie: When mice with PrPC-ablated FDC (Prnpflox/-→CD21-Cre Prnpflox/- mice) were injected intracerebrally (i.c.)with the ME7 scrapie agent strain directly into the CNS all mice succumbed to clinical signs of scrapie approximately 300 days after exposure with incubation periods indistinguishable from those of Prnp+/- control mice [43] (Prnpflox/-→CD21-Cre Prnpflox/-, 297±4 days, n = 4; Prnp+/-, 290±4 days, n = 5; P = 0.386).