Splicing suppression alters the STING transcription start site to attenuate antiviral innate immunity.

Abstract

The cGAS (cyclic GMP-AMP synthase)-STING (Stimulator of interferon genes) pathway plays a central role in antiviral innate immunity in vertebrates. Recent studies have shown that invertebrates possess a related cGLR (cGAS-like receptor)-STING pathway. However, due to the lack of direct evidence demonstrating viral evasion of cGLR-STING-mediated immunity, the functional importance of cGLR-STING pathway in antiviral responses remains uncertain in invertebrates. Here, we show that an insect picorna-like virus CrPV (Cricket Paralysis virus) inhibits STING-mediated antiviral activity by altering the transcription start site of STING. Mechanistically, CrPV infection down-regulates several spliceosomal genes and disrupts pre-mRNA splicing. This splicing impairment is sufficient to stall RNA polymerase II in transcriptional initiation condensates, reduce global transcription efficiency, and reprogram the transcription start site of STING. Such a shift diverts STING expression from a functional antiviral isoform to a nonantiviral variant that partially suppresses STING activity, thereby disabling the cGLR-STING pathway. Our findings uncover an unconventional viral immune evasion strategy and an unexpected link between splicing suppression and STING-mediated antiviral response. Given the evolutionary conservation of splicing mechanisms and STING-like pathways, this mechanism may represent a broadly applicable regulatory principle in immune defense across species.