Leader-Containing Uncapped Viral Transcript Activates RIG-I in Antiviral Stress Granules

Rig-i triggers antiviral responses by recognizing viral rna (vrna) in the cytoplasm. however,the spatio-temporal dynamics of vrna sensing and signal transduction remain elusive. we investigated the time course of events in cells infected with newcastle disease virus (ndv),a non-segmented negative-strand rna virus. rig-i was recruited to viral replication complexes (vrc) and triggered minimal primary type i interferon (ifn) production. rig-i subsequently localized to antiviral stress granules (avsg) induced after vrc formation. the inhibition of avsg attenuated secondary ifn production,suggesting avsg as a platform for efficient vrna detection. avsg selectively captured positive-strand vrna,and poly(a)+ rna induced ifn production. further investigations suggested that uncapped vrna derived from read-through transcription was sensed by rig-i in avsg. these results highlight how viral infections stimulate host stress responses,thereby selectively recruiting uncapped vrna to avsg,in which rig-i and other components cooperate in an efficient antiviral program. © 2016 oh et al.