Detection of prion seeding activity by RT-QuIC. RT-QuIC was performed using SHrPrP (90–231) as substrate. A Brain homogenate from two sheep inoculated with classical scrapie (positive control 1 and 2) and homogenate from a known scrapie-negative sheep (negative control) were used to assess the overall performance of the RT-QuIC. B Hippocampal homogenates diluted at 10 −2 or 10 −3 were analyzed as described in materials and methods. Inserted graph shows amplification of sample #536 at a slightly modified experimental protocol. Samples were analyzed in triplicates and the curves show the average fluorescence intensity at each time point.