FIG. 2.
Titers of influenza PR8 and delNS1 virus in PKR+/+ and PKR−/− mice. Female mice at 7 to 9 weeks of age were used for infection with 105 PFU of wt PR8 or delNS1 virus. Virus was applied intranasally in a volume of 50 μl under ether anesthesia. To determine viral replication in the respiratory tracts, three mice of each group were sacrificed at day 2, 4, or 6 after inoculation. Lungs were removed and homogenized in 3 ml of phosphate-buffered saline. The quantity of virus in homogenates from each mouse was determined by titration on Vero cells. Virus titers are expressed as the number of PFU per milliliter of tissue extract. (A) Titers in PKR+/+ mice. (B) Titers in PKR−/− mice. The standard error of the mean is indicated.