Fig. 4.

Activation of p38 MAPK and JNK is required at early stages of PEDV infection but does not affect virus internalization. (A) Vero cells were pretreated with DMSO, SB202190 (5 and 10 μM), or SP600125 (1 and 5 μM) and were mock or PEDV (MOI of 1) infected. At the indicated time points post-infection, each inhibitor was added to attain the intended final concentration. At 48 hpi, the virus-infected cells were fixed, and virus infectivity was determined by measuring the percentage of cells expressing N proteins through FACS. (B) Virus internalization assay. Vero cells were infected at an MOI of 1 at 4 °C for 1 h. After washing with cold PBS, the infected cells were incubated with or without each inhibitor either at 4 °C or 37 °C for an additional hour. Bound but non-internalized viral particles were removed by treatment with proteinase K. The infected cells were then serially diluted and plated onto Vero cells in 96-well tissue culture plates. At 2 days post-incubation, internalized viruses were titrated by a plaque assay. The results are expressed as the mean values from triplicate wells, and the error bars represent standard deviations. *, P < 0.05; **, P < 0.001.