FIG 3.
Furin inhibitor blocks trypsin-independent entry and formation of syncytia by PEDV-SFCS in human hepatoma (Huh-7) cells. (a) Cells were inoculated with PEDV-SWT or PEDV-SFCS at an MOI of 0.5 (the MOI was based on virus infectivity on Vero cells in the presence of trypsin). The furin inhibitor decanoyl-Arg-Val-Lys-Arg-chloromethylketone (FI; 40 μM) was present in the cell culture supernatant from −1 h to 2 h p.i. or from 2 h to 12 h p.i. To prevent trypsin-mediated entry, soybean trypsin inhibitor (SBTI; 40 μg/ml) was present in the culture supernatant throughout the experiment. Cells were fixed at 12 h p.i. Nuclei were stained with DAPI (blue), and images of PEDV-infected cells (GFP positive; green) were acquired. Experiments were repeated two times, and representative images are shown. (b) Huh-7 cells were infected with PEDV-SWT and PEDV-SFCS in the presence of trypsin inhibitor for 2 h and further cultured in the absence or presence of furin inhibitor, as described for panel a. At 12 h p.i., the numbers of nuclei per focus of infection were counted.