Endpoint dilution of prion-infected brain homogenates by RT-QuIC.

Representative RT-QuIC experiments testing a ten-fold dilution series of (A) reference BSE-infected sheep brain tissue and brain tissue from mock-infected negative control sheep (NBH), and (B) reference vCJD-infected human brain tissue 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 50 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). A total of 14 negative control reactions were tested per RT-QuIC plate (as indicated by arrows). SD₅₀ values ± standard error of the mean (SEM) shown in boxes. Horizontal dashed lines indicate threshold fluorescence.