mTORC1 activation promotes viral infection.

<p>(<b>A</b>) A549 cells were infected with WSN at MOI of 2 PFU/cell for 1 h and then treated with 250 nM Torin1 or DMSO for an additional 9 h followed by immunoblot analysis. (<b>B</b>) A549 cells were infected at MOI of 0.01 PFU/cell with WSN for 16 h in the presence of the depicted concentrations of Torin1 or DMSO. Viral titers were measured by plaque assay to yield plaque-forming units per mL (PFU/ml, plotted as % infection relative to DMSO control). Cell survival was also assessed at the depicted concentrations using the MTT assay. The following parameters were calculated: CC₅₀>500 nM; IC₅₀ = 0.46nM; and SI>1087. (<b>C</b>) Experiment was performed as in <b>B</b> except that cells were treated with 13.7 μM rapamycin or DMSO as control. Mean and standard error of the mean (SEM) are shown. <i>n</i> = 3, **p<0.01. (<b>D</b>) <i>Rictor</i>^<i>+/+</i> or <i>Rictor</i>^<i>-/-</i> MEFs were infected with WSN at MOI of 2 PFU/cell for 6 h and treated with 250 nM Torin1 or DMSO at 1 h post-infection. Immunoblot analyses were performed to detect viral proteins (HA, NP, PA, PB1, PB2, NS1, M1, M2 and NA) and host proteins (β-actin, Rictor, total and phosphorylated S6K and 4E-BP1). β-actin and S6K serve as loading controls. The upper band in the S6K/p-S6K blots is p85 S6K whereas the lower band is p70 S6K. (<b>E</b>) <i>Rictor</i>^<i>+/+</i> or <i>Rictor</i>^<i>-/-</i> MEFs were infected with WSN at MOI of 0.01 for 24 h and 48 h. Viral titers were measured by plaque assay to yield plaque-forming units per ml (PFU/ml). Mean and standard deviation (SD) are shown, <i>n</i> = 3, **p<0.01, *p<0.05.