Determination of 50 h cut-off time for RT-QuIC endpoint dilution experiments.

Ten-fold dilutions of (A) a reference BSE-infected sheep brain tissue homogenate and brain tissue from mock-infected negative control sheep (NBH), or (B) a reference vCJD-infected human brain tissue homogenate and negative control human brain tissue. RT-QuIC was performed using truncated ovine recPrP (residues 94–233) as a substrate. Fluorescence measurements were plotted over 90 h. Data points represent the mean ThT fluorescence from n = 10 replicates (for prion-infected brain dilutions), or n = 2 replicates (for negative control brain dilutions). False positives start to appear in 1/2 or 2/2 replicates at given negative control brain dilutions after 50 h (as indicated by arrows).

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