Fig. 4.

25HC inhibits PDCoV proliferation. (A) Assessment of the cytotoxicity of 25HC against IPI-FX cells. IPI-FX cells were incubated with different concentrations of 25HC or EtOH for 24 h and then evaluated using a MTT assay. (B–E) IPI-FX cells were pretreated with 25HC at the indicated concentrations for 8 h prior to PDCoV infection in the presence of 2.5 μg/mL trypsin (MOI 0.5). The infected cells were cultured in the presence of 25HC and harvested at 12 or 18 hpi for the plaque assay (B), qRT-PCR (C) or IFA (D, E). IFA was performed using a specific antibody against PDCoV N protein. Scale bar =50 μm. All data are presented as the means ± standard deviations of three independent experiments. *P < 0.05 and **P < 0.01.