mTOR activator MHY1485 reverses the repression of PRRSV replication by PP242. (a–d) Cells were pretreated with 2 µM PP242 for 12, 24, 36 or 48 h, then infected with DsRed-labelled PRRSV along with MHY1485 or rapamycin at different concentrations, and quantified with a SpectraMax i3 at 36 h p.i.; n=3; a, b and c indicate p<0.001, 0.01, and 0.05, respectively, relative to the control. Rapa, Rapamycin; MHY, MHY1485.