Fig. 5.

Inhibition of the mTOR signalling pathway promotes type I IFN production and signalling. MARC-145 cells were treated with mTOR inhibitors (rapamycin and PP242) and activator (MHY1485) for 24 h, and then infected with DsRed-labelled PRRSV (m.o.i. of 1) for another 24 h. Cell culture supernatants were collected and PRRSV was inactivated with UV illumination. Supernatants were used to measure IFNs with an ELISA for detection of IFN-α subtypes (a), or a bioassay in MARC-145 cells stably transformed with an IRF3-, IRF7- or Mx1-promoter driven luciferase reporter system (b–d); n=3; a, b and c indicate p<0.001, 0.01 and 0.05, respectively, relative to the control.