FIG 3.

Evaluating the interferon responses to icPEDV infection in PK1 cells. PK1 cells were mock infected or infected with the indicated strain of PEDV at a dose of 0.1 TCID₅₀ per cell. At 24 HPI, cells were lysed to collect total RNA for cDNA synthesis, and quantitative PCR was used to measure the relative levels of expression of the indicated mRNAs for IFN-β (A), IFN-γ1 (B), ISG54 (C), and the N gene (D). The level of gene expression in the wild-type-virus-infected samples was assigned a value of 1, and the fold change in expression is indicated relative to the PEDV wild-type-virus-infected sample. Values are presented as means ± SD and were analyzed by unpaired t test. *, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001.