Fig. 4: Viral quantification using Cas12 and Cas13 in combination.
a, Schematic of the procedure for the use of both Cas12 and Cas13 for quantification of viral copy number in samples. Fluorescence was plotted over time to determine the time at which fluorescence signal reaches 50% calculated as the IC50 value at each concentration using a sigmoidal 4PL fit. The IC50 values were then plotted by concentration to generate a semilog line with an R2 > 0.8 for Cas12 and Cas13 individually. After line generation, the IC50 value of each patient sample was plotted onto these lines to determine viral copies μl−1. b, Normalized fluorescence ratio of Cas13 crRNA (top) and Cas12 crRNA (bottom) signal over time at varying concentrations of synthetic SARS-CoV-2 Orf1ab RNA. c, Plots showing the semilog lines generated by IC50 values from the Cas12 and Cas13 crRNA signals and the Ct values from RT–qPCR for more than four target concentrations of SARS-CoV-2 (left) and FLUAV (right) synthetic RNA. Blue: Cas13; orange: Cas12; gray: Ct from RT–qPCR. d, Comparison of mCARMEN IC50 values to RT–qPCR Ct values using linear regression, with the best line fit shown as a dashed line. Black: SARS-CoV-2; gray: FLUAV.
