Protein misfolding cyclic amplification (PMCA) is an assay that mimics the PrP Sc propagation process under cell-free conditions. In this method PrP Sc is amplified by converting PrP C to a PrP Sc seed during incubation with periodic sonication [15] . PrP Sc generated by PMCA is infectious in wild-type animals [16] and can be indefinitely propagated while preserving the properties of the original PrP Sc strain [16] [17] [18] . Furthermore, PMCA has been quite useful in studying the cofactors that influence PrP conversion [19] [20] [21] [22] [23] [24] [25] [26] , and in detecting PrP Sc from biological samples of humans and animals [17, [27] [28] [29] [30] [31] [32] [33] [34] .