Fig. 4.

PKR suppresses replication of ΔE3L-SPPV34L and ΔE3L-YMTV34L. (A) HeLa cells were mock transfected or transfected with control or PKR siRNA at 100 nM for 48 h. Western blotting was used to determine the expression of PKR and actin. (B) HeLa cells were treated as in panel A and then infected at an MOI of 1 with the indicated virus. Cells were collected at 24 hpi, and virus yields were determined by plaque assays in BHK21 cells. (C) eGFP expression was analyzed by fluorescence microscopy at 24 hpi in the siRNA-treated, virus-infected cells evaluated in panel B. Microscope settings were kept consistent for all images taken. (D) HeLa cells were mock transfected or transfected with control, RNase L, or PKR siRNA at 100 nM for 48 h. Cells were also transfected with both RNase L (50 nM) and PKR siRNA (50 nM) for 48 h. The expression of GAPDH and RNase L was analyzed by RT-PCR. (E) HeLa cells were transfected as in panel D and then infected at an MOI of 1 with the indicated virus. The cells were collected at 24 hpi, and virus yields were determined by plaque assays in BHK21 cells. The results are representative of three independent experiments. Error bars represent the standard errors of the mean. The “*” symbol signifies statistically significant differences (P < 0.05) in virus yield in comparison to control siRNA-treated cells infected with the same virus.