Mediates the regulatory switch from transcription to RNA replication. Acts late in infection by inhibiting viral transcription and up-regulating RNA replication (By similarity). Plays a major role in antagonizing the type I IFN-mediated antiviral response. Interacts with host MAVS and prevents the interaction with its upstream partner DDX58/RIG-I in the signaling pathway leading to interferon production (By similarity). Interacts with host MAVS; this interaction inhibits signaling pathway leading to interferon production. Belongs to the metapneumovirus M2-2 protein family.