FIG 2.

LCMV activates the PI3K/Akt pathway. (A) LCMV infection induces Akt phosphorylation. A549 cells were infected with LCMV (MOI of 3) or left uninfected (U) in the presence of the PI3K inhibitor LY294002 or vehicle alone (dimethyl sulfoxide [DMSO]). Cells were lysed at the indicated time points, and phosphorylation of Akt (pAkt) was assessed by Western blotting using a phosphospecific antibody. Expression of Akt was detected with a phosphorylation-insensitive antibody. Signals were analyzed by densitometry, and the ratio of phospho-Akt/Akt calculated with uninfected cells was defined as 1. At 24 h postinfection an additional band (*), distinct from phosphorylated Akt (pAkt), was detected in the presence of LY294002. (B) Inhibition of PI3K activation does not induce apoptosis in LCMV-infected cells. A549 cells were infected with LCMV (MOI of 3), SeV (80 hemagglutinin units/ml), or left uninfected (u) in the presence or absence of LY294002 as described for panel A. Activation of caspase 3/7 was assessed at the indicated time postinfection as described in the legend of Fig. 1A. Staurosporine (St) treatment (3 μM for 8 h) was used as a positive control. Data presented are normalized to values of uninfected (u) cells (n = 3; means ± standard deviations). Statistical analysis for SeV-infected specimens was performed by one-way ANOVA comparing results for specimens treated with LY294002 with those for specimens treated with vehicle (DMSO). For LCMV, we compared results for LCMV-infected cells with those for staurosporine-treated cells. P values are indicated. n.s., not significant (P > 0.05).