Plays an essential role in transcription initiation and cap-stealing mechanism, in which cellular capped pre-mRNAs are used to generate primers for viral transcription. Binds the cap of the target pre-RNA which is subsequently cleaved after 10-13 nucleotides by PA. Plays a role in the initiation of the viral genome replication and modulates the activity of the ribonucleoprotein (RNP) complex. In addition, participates in the inhibition of type I interferon induction through interaction with the host mitochondrial antiviral signaling protein MAVS. Influenza RNA polymerase is composed of three subunits: PB1, PB2 and PA. Interacts (via N-terminus) with PB1 (via C-terminus). Interacts with nucleoprotein NP (via N-terminus). Interacts (via N-terminus) with host MAVS (via N-terminus); this interaction inhibits host innate immune response. Belongs to the influenza viruses PB2 family.