Figure 2.

Clone reporter systems for SARS-CoV-2. (a,b) Representative images of SARS-CoV-2 Spike, SARS-CoV-2 Nucleocapsid, and GFP channels, together with an overlay of all channels including the nucleus, from a time-course infection experiment (MOI 0.01) of (a) wild-type clone (WT) and (b) GFP-reporter viruses, taken with a 40× objective. (c) Titration of nLuc and Fluc reporter activity of SARS-CoV-2 reporter viruses with initial infectivity titers of 5.5 and 5.3 Log TCID₅₀/mL, respectively. The values of relative light units (RLU) measured at 24 h were subtracted from negative control wells and normalized to the values obtained from the 10⁻¹ virus dilution. The data points represent mean of quadruplicates; error bars represent standard error of the mean. For some data points the differences are too small to plot error bars.