FIG 4.

IL-6 and IL-1β can increase cell diameter but do not affect infectivity of SARS-CoV-2. (A) The changes in cell diameter with IL treatment and/or infection were measured using ImageJ. Cell diameters for two different CM lines were measured and plotted. We observe a statistically significant increase in cell size with infection but a larger increase in cell diameter with ILs only or ILs and infection with SARS-CoV-2. Statistical significance was determined by one-way ANOVA with Bonferroni multiple-comparison test: *, P < 0.05; **, P < 0.01. (B) We counted the numbers of cells stained by NP protein antibody as a measure of infectivity. Each point is representative of one well of a 96-well plate with 10,000 CM cells. The bar graph is the average of four different CM lines measuring viral NP protein-positive cells over the total number of cells. Counting was done in an automated fashion using the IN Cell Analyzer. ILs do not increase the percentage of CM cells infected by SARS-CoV-2. (C) To confirm that CMs were being productively infected and shedding SARS-CoV-2 into the culture medium, we collected supernatants from 3 different CM lines 48 and 72 h postinfection, with or without ILs, and performed a TCID₅₀ plaque assay. We observed that the CM lines were infected, and the level of infection, as assessed by virus release into culture medium, did not increase with the addition of IL-6 and IL-1β.