Fig. 1.

Detection of antiviral activity in cell culture supernatant from A2MC2-infected MARC-145 cells. (A) Inhibition of NDV-GFP replication in Vero cells. Vero cells were treated with dilutions of cell culture supernatant of A2MC2-infected MARC-145 cells. The Vero cells were inoculated with NDV-GFP 12 h after the treatment, and observed under fluorescence microscopy at 24 h post-infection. Treatment of the cells with IFN-α at a final concentration of 1000 U/ml was included as a positive control. (B) Elevation of STAT2 and ISG56 proteins in Vero cells after treatment with the supernatant from A2MC2-infected MARC-145 cells detected by Western blot analysis. Vero cells treated with IFN-α and mock-treated were included as positive and negative controls, respectively. Blotting with β-tubulin antibody was done to normalize protein loading. (C) Inhibition of A2MC2 replication in MARC-145 cells by PRRSV-specific peptide-conjugated phosphorodiamidate morpholino oligomer (PPMO) 5UP1. A scrambled control PPMO CP1 was included as a negative control. An indirect immunofluorescence assay with PRRSV N-specific monoclonal antibody was conducted. The bottom panel of images shows the nuclear DNA stained with 4′,6-19 diamidino-2-phenylindole (DAPI). (D) Detection of PRRSV proteins in whole cell lysate of A2MC2-infected cells (A2 lane) by Western blotting with pig antiserum. Cell lysate samples from PRRSV VR-2385-infected (VR lane) or MLV-infected cells were included as positive controls. Molecular weight markers are illustrated on the left.