Figure 2.

Optimization of cell-seeding density. In this 1536-well format, a range of seeding concentrations were tested to determine the lowest concentration of cells per well that yielded an acceptable Z’. Comparison of papain-like protease (PLpro) firefly luciferase (FLuc) (shown in red) versus enterovirus (EV) FLuc (black) allowed us to select the cell number that afforded the best condition for the high-throughput screening (HTS) effort (see text). The medium-only control (gray) was used to demonstrate no activity would be found when cells aren’t present (i.e., background).