Figure 1. Relative performances of vCJD/BSE agent amplification by Protein Misfolding Cyclic Amplification using brain from transgenic mice expressing different species PrP sequences as substrate.

PMCA reactions were seeded with ten-fold dilution series of vCJD/BSE brain material (10⁻² to 10⁻⁹) from different species (human, cynomologus macaque, bovine, ARQ sheep and porcine). PMCA substrates were prepared using brain from transgenic mice over-expressing either human (methionine 129 variant, □), bovine (▿), murine (○) or sheep (VRQ variant:▵, ARQ variant:▴) Prion protein. Unseeded reactions were included as specificity control. PMCA reactions were then submitted to 2 to 6 amplification rounds each constituted with 96 cycles (30 s sonication-30 minutes incubation at 39.5°C) in a Misonix 4000 sonicator. After each round, (i) reaction products (1 volume) were mixed with fresh substrate (9 volumes) to seed the following round while (ii) a part of the same product was analysed by Western Blot (WB) for the presence of abnormal PK resistant PrP (PrP^res -antibody Sha31 epitope YEDRYYRE). For each round, the last dilution displaying a positive signal in WB is indicated on the graph.