Figure 4

Pantethine treatment reduced SARS-CoV-2 infection in Calu-3 cell cultures. Full-time treatment with pantethine reduced the infection of Calu-3 cells by SARS-CoV-2 (MOI 0.05) significantly and in a dose-dependent manner. (A) Forty-eight hours post-infection, cells were collected and stained to determine viability and infection rates through the detection of the viral spike (S) protein in cells by flow cytometry analysis. Data represent the percentage of mortality and (B) the percentage of infection observed with the flow cytometry analysis experiments and are shown as the mean + SEM of results obtained from 3 independent experiments with 3 independent points per condition. (C) Forty-eight hours post-infection, cells were lysed with RIPA buffer, and western blot analyses were performed to detect the expression of the viral spike (S), the full length and S1 domain, and the nucleocapsid (N) proteins. GAPDH was used as a loading control. The numbers below the blots represent relative expression levels. For each viral protein, the levels of the uninfected cells were set at 1. Virus yields in infected cells (D) and in their supernatants (E) were quantified by qRT-PCR for the viral N gene. Calculated Ct values were converted to the fold-reduction of samples compared to the housekeeping gene GAPDH (for cells) or to noninfected cells (for supernatants) using the ΔΔCt method (fold change in viral RNA = 2^−ΔΔCt). In (D) and (E), the results represent the mean + SEM. (F) An inhibitory dose–response curve based on viral N gene expression in supernatants was used to determine the IC50 using GraphPad Prism software. The results represent the mean ± SEM. In all experiments, the results were obtained from 3 independent experiments. ****p < 0.0001 compared to the control group (infected-untreated cells) by one-way ANOVA followed by Dunnett's post hoc test.