RIGI and viral infectious disease: Recent studies have identified a new molecule that acts as a protein activator of protein kinase R (PKR), namely protein activator of the interferon-induced protein kinase (PACT) [21, 22], and also promotes RIG-I signaling in response to viral infection and dsRNA through interacting with the carboxy-terminal domain (CTD) of RIG-I, which in turn stimulates RIG-I ATPase activity [23, 24].