TMPRSS2 inhibition assay

Calu-3 cells were seeded onto a 48-well plate 24 hours prior to treatment. Cells were incubated with 5 μM of Camostat mesylate (Sigma Aldrich, SML0057) for 30 mins prior to virus infection and throughout the 1 hour virus infection. After infection, fresh media containing Camostat mesylate was added to the cells and incubated for another 24h. Cells were then harvested 24 hpi.

In order to quantify infected cells from indirect immunofluorescent stained samples, ilastik 1.2.0 was used on DAPI images to generate a mask representing each nucleus as an individual object. These masks were used on CellProfiler 3.1.9 to measure the intensity of the conjugated secondary antibodies in each nucleus. A threshold was set based on the basal fluorescence of non infected samples, and all nuclei with a higher fluorescence were considered infected cells.