To Conquer the Host, Influenza Virus Is Packing It In: Interferon-Antagonistic Strategies beyond NS1

The nonstructural protein NS1 is well established as a virulence factor of influenza A virus counteracting induction of the antiviral type I interferon system. Recent studies now show that viral structural proteins, their derivatives, and even the genome itself also contribute to keeping the host defense under control. Here, we summarize the current knowledge on these NS1-independent interferon escape strategies.