Among the influenza viral proteins, the NS1 has been identified as the main type I IFN antagonistic factor. So far two major mechanisms have been described by which NS1 suppresses the initial expression of IFNb. On the one hand NS1 inhibits vRNAmediated induction of the transcription factors interferon regulatory factor-3 (IRF-3), activating protein-1 (AP-1) and NF-kB that target the IFNb promoter. This most likely occurs via binding to the RNA-sensor retinoic acid inducible gene (RIG-I) and inhibition of RIG-I-mediated signaling in response to viral RNA [1, 2] . On the other hand NS1 inhibits maturation [3, 4] and nuclear export of host mRNAs [5] . Other functions of the multifunctional protein include block of activation of the dsRNAactivated protein kinase PKR by direct interaction [6] or activation of the phosphatidylinositol-3 kinase PI3K/Akt pathway to prevent premature apoptosis induction [7, 8] .