Fig. 3.

SARS-CoV-2 was inactivated by PLE. (A) The virus stock was pre-treated with increasing concentrations of PLE, and the remaining viral titers were subsequently determined using a plaque assay carried out in Vero E6 cells. The number of plaques for PLE-treated viruses was normalized to that of the virus control (arbitrarily set to 1). Data are expressed as means ± standard error of the mean from at least three independent experiments. (B–C) Confocal immunofluorescence microscopy revealed that PLE treatment reduced viral protein synthesis in Calu-3 cells. Cells treated with or without remdesivir and PLE were infected with SARS-CoV-2 at a MOI of 0.01. Cells were harvested at 48 h p.i. for confocal microscopy using the anti-S antibodies as indicated. Fluorescence images of S protein subcellular distribution in SARS-CoV-2-infected Calu-3 cells obtained either in absence (B) or presence (C) of inhibitors. Magnifications of objective lenses: 100 × (B) and 20 × (C). Nuclei were stained with a Hoechst dye. The transmitted light in the bright field revealed the overall morphology of Calu-3 cells. The bar chart in the right panel illustrates the ratios of infected cells under different experimental conditions (magnification of objective lens: 20 × ). For each condition, the ratio of spike-positive cells was calculated in two independent experiments from >200 cells in randomly selected fields. ∗p < 0.05, ∗∗p < 0.01, and ∗∗∗p < 0.005.