Enzymatic synthesis and purification of a defined RIG-I ligand.

Receptor-based nucleic acid sensing constitutes one of the most fundamental mechanisms of our innate immune system to sense viral infection. RIG-I is a cytosolic RNA helicase that senses the presence of 5' triphosphate RNA species, a common feature of many negative strand RNA viruses. We here describe a protocol to enzymatically synthesize and to purify a defined RIG-I ligand that can be used to study RIG-I activation in vitro and in vivo.