The aim of this proposal is to understand how anti-viral immunity is triggered by one specific yet pivotal immune sensor. Our understanding of how this immune sensor initiates anti-viral immunity is limited, yet it plays an essential role in protecting us from infection against prominent viruses like influenza, hepatitis C and measles. By enhancing our fundamental knowledge of anti-viral immune activation we may learn to understand the detailed mechanisms by which viruses subvert the immune response to avoid detection. This proposal will focus specifically on immune evasion by influenza A. The outcome will be a significant advancement in knowledge that may in the future contribute to the design of anti-viral therapies and vaccines.