A transgenic mouse line expressing human PrP with four amino acid substitutions (M166V, E168Q, S170N, and N174T) that resulted in the expression of a human PrP with a cervine rigid loop structure showed prolonged incubation periods when challenged with human sporadic CJD but were susceptible to CWD infection [75]. Here, PRNP is linked to sporadic Creutzfeldt-Jakob disease.