FIG. 5.

(A) Effect of alpha/beta interferon on replication of recombinant viruses in PKR^+/+ and PKR^−/− mouse fibroblast cells. Cells were pretreated with mouse alpha/beta interferon (1,000 U/ml) for 20 h. Cells were then either mock infected (PKR−) or infected with the recombinant viruses (PKR+) at 0.05 PFU per cell and incubated at 37°C for 48 h. Cells were harvested and freeze-thawed three times, and virus yield was determined on Vero cells. The data represent the averages of triplicate samples, with the standard deviations indicated by error bars.