FIG 1.

N protein significantly inhibits SEV-induced expression of IFN-β and ISGs. HEK-293T cells grown in 24-well plates were transfected with 1 μg of a plasmid encoding PEDV N protein (pCAGGS-HA-N) or an empty vector, and 24 h later, the cells were infected with SEV (10 hemagglutinating activity units/well). Twelve hours after infection, the cells and supernatants were collected separately. (A and C to E) Total RNA was extracted from cells, and the expression levels of the IFN-β (A), ISG56 (C), ISG54 (D), ISG20 (E), and GAPDH genes were evaluated by quantitative real-time RT-PCR. The results are expressed as increases in mRNA levels relative to those in cells transfected without SEV infection and were normalized to the expression level of the GAPDH housekeeping gene. (B) The harvested supernatants were used to detect IFN-β by an ELISA. Anti-HA antibody was used to confirm the expression of PEDV N protein, and anti-β-actin antibody was used to detect β-actin, which served as a protein loading control. The results are representative of data from three independent experiments. WB, Western blot.