Figure 1.

IFN-β failed to inhibit EV71 replication. Vero cells were pretreated with or without IFN-β at concentrations as indicated for 2 h and then infected with EV71 at an m.o.i. of 0.2. A, cytopathic effects of infected cells pretreated with IFN-β. The infected or uninfected cells were fixed at 72 h p.i. with 3% formaldehyde and stained with 0.5% crystal violet. After washes the cells were subjected to light microscopy. The assay was performed in duplicate (top and bottom rows). B, the culture medium supernatants from the cells were harvested at 48 h p.i., and infectious viral titers (TCID₅₀) were determined for the cells pretreated with IFN-β at various concentrations. C, total RNA was isolated from the cells pretreated with IFN-β for real-time RT-PCR to measure viral VP1 gene copy numbers. D, cell lysates were prepared from infected or uninfected cells and then pretreated with IFN-β for Western blot analyses with anti-VP1 antibodies. The experiments were performed at least twice, and representative results are presented. NS, p > 0.05 (Student's t test); MW, molecular mass.