HPIV3 triggers SG formation in a PKR-dependent manner.

(A and B) HeLa cells with or without PKR knockdown were infected with HPIV3 (MOI = 1) for 24 h. (A) Cells were immunostained for HPIV3 (green) and G3BP (red). Nuclei were stained with DAPI (blue). The white scale bar corresponds to 10 μm. (B) The percentage of cells containing SGs was quantified in three independent experiments. (C and D) HeLa cells with or without PKR knockdown were transfected with RNA from HPIV3-infected MK2 cells for 12 h. (C) Cells were immunostained for TIA-1 (green) and G3BP (red). Nuclei were stained with DAPI (blue). The white scale bar corresponds to 10 μm. (D) The percentage of cells containing SGs was quantified in three independent experiments. (E and F) HeLa cells with or without PKR knockdown were mock-infected or infected with HPIV3 (MOI = 1) for 24 h. (E) Cell lysates were analyzed via western blot using anti-HN, anti-phosphorylated PKR, anti-PKR, anti-phosphorylated eIF2α, anti-eIF2α, and anti-GAPDH antibodies. (F) The supernatants were collected for a plaque assay to determine the viral titer. Data are represented as means ±SD. Student’s t test: * P<0.05, ** P<0.01, *** P<0.001, ns = not significant.