Figure 5. The 1,212 nucleotide-long 5′ copy-back MV DI-RNA triggers efficient IFN type I production via RIG-I. (A) Immunostimulatory activity of RNA from MV-N upon transfection into STING-37 cells. MV-N affinity chromatography-purified RNAs were compared with RNAs purified from negative control (CH)-tagged protein. Samples were analyzed in triplicates with standard deviation represented on the figure, and two biological replicates were performed. (B) The 1,212 nucleotide-long DI genome of MV induces RIG-I mediated type-I IFN signaling. STING-37 reporter cells were transfected with siRNA targeting RIG-I, MDA-5, MAVS or TPR (negative control) or mock transfected. Second transfection of the cells was performed 48 h later with either 1,212 nucleotide-long MV DI-RNA, poly(IC) or 5′PPP-bearing short RNA. Luciferase induction fold is expressed as the ratio of luciferase measured within stimulated by second RNA transfection cells to the ratio of luciferase in cells left without the second transfection. Samples were analyzed in triplicates and two biological replicates were performed. The SEMs are shown in the figure.