2-5A (5'-O-Triphosphoryladenylyl- (2'→5') -adenylyl- (2'→5') -adenosine) pentasodium is a 5'-triphosphorylated (2',5') oligoadenylate. 2-5A pentasodium is an immunotransmitter that fuels RNase L immunity. 2-5A pentasodium degrades viral mRNA and inhibits protein synthesis by binding to RNase L and activating its endoribonuclease activity. 2-5A pentasodium can be used in RSV and cancer research[1][2][3][4].