Figure 3. P58^IPK−/− mouse lungs exhibit increased eIF2α and PKR phosphorylation during influenza virus infection.

Three P58^IPK−/− and wild-type mice were infected with 10⁴ (A,B) or 10³ (C,D) PFU of the PR8 strain of influenza virus. At 1 and 3 days post infection, azygous and apical lung lobes were excised and homogenized. (A) Equivalent concentrations of protein in lung homogenates were subjected to SDS-10% PAGE. The levels of phosphorylated or total eIF2α and actin were determined by immunoblot analysis. (B) Densitometry analysis of (A). The density of the eIF2α-P band was normalized to the density of the total eIF2α band, which is represented graphically. (C) 400 µg of total protein from lung homogenates was used for immunoprecipitation with an antibody for total PKR. Following immunoprecipitation, protein samples were clarified by SDS-10% PAGE and the levels of phosphorylated or total PKR were determined by immunoblot analysis. (D) Densitometry analysis of (C). The density of the P-PKR band was normalized to the density of the total PKR band, which is represented graphically. The results represent the mean activity of 3 biologically independent samples±standard deviation. P-values from a two-tailed t-test assuming non-equal variance are indicated (*: P<0.05, **: P<0.05).