FIG 7.

De novo synthesis of viral RNA is not required for IFN expression. (A) L929 cells were infected with 10 PFU/cell of T3D. Levels of IFN-β mRNA were assessed at the indicated time intervals by using RT-qPCR. The IFN-β/GAPDH ratio at 0 h postinfection was set to a value of 1. *, P < 0.05 compared to cells infected for 0 h. (B) L929 cells treated with AC (20 mM), ribavirin (200 μM), or GuHCl (15 mM) were infected with 10 PFU/cell of T3D. Levels of IFN-β mRNA were assessed by RT-qPCR at 24 h postinfection. The IFN-β/GAPDH ratio for untreated, T3D-infected cells was set to a value of 1. *, P < 0.05 compared to control treated, infected cells. (C and D) L929 cells were infected with 10 PFU/cell of T3D and equivalent numbers of particles of UV-treated T3D. (C) Levels of reovirus plus-strand RNA corresponding to the viral S1 gene segment were measured by RT-qPCR at 24 h postinfection. The ratio of the reovirus T3D S1 plus strand to GAPDH in cells infected for 0 h was considered to have a value of 1. UD, undetectable (value below that detected at 0 h). (D) Levels of the corresponding reovirus IFN-β RNA were measured by RT-qPCR at 24 h postinfection. The IFN-β/GAPDH ratio in cells infected with infectious T3D was considered to have a value of 1. (E) L929 cells were transfected with nontargeting siRNAs or siRNAs specific for MAVS. Levels of IFN-β mRNA in cells infected with 10 PFU/cell of T3D in the presence or absence of ribavirin (200 μM) were assessed by RT-qPCR. The IFN-β/GAPDH ratio for untreated, T3D-infected, nontargeting siRNA-treated cells was set to a value of 1. *, P < 0.05 compared to untreated, T3D-infected, nontargeting siRNA-treated cells.