These immunofluorescence-based antiviral assays rely on identification of infected cells through immunostaining the NP (influenza virus), N (SARS-CoV-2) proteins, or any relevant viral antigen at 488nM and counterstaining with DAPI. Infected cells (488nM) and total cells (DAPI) are identified andquantified by a plate cytometer (Biotek Cytation 1). Compounds are tested in a triplicate 8-pointdose-response with concurrent cytotoxicity assays (MTT Roche/MTS Promega) in uninfectedcells. These assays can be run on any adherent cell type, such as standard cell lines and iPSC-derived cell types. DMSO infection controls (negative) and uninfected cell controls (positive) should be included on every plate. The DMSO controls will establish 100% infection and the uninfected wells 0% infection for each plate. Relevant control compounds should be included as controls for every run. The effect p-gp inhibitors on known p-gp subtrates should be explored in all new cell types used. These assays accurately reflect the antiviral activity of compounds in medium-to-high throughput, depending on the level of automation.
McGovern et al. (Wed,) studied this question.