In mammalian cells, IFN responses that occur during
RNA and
DNA virus infections are activated by distinct signaling pathways. The RIG-I-like-receptors (RLRs) bind
viral RNA and engage the adaptor MAVS (mitochondrial
antiviral signaling) to promote IFN expression, whereas cGAS (cGMP-
AMP synthase) binds
viral DNA and activates an analogous pathway via the
protein STING (stimulator of IFN genes). In this study, we confirm that
STING is not necessary to induce IFN expression during
RNA virus infection but also find that
STING is required to restrict the replication of diverse RNA viruses. The
antiviral activities of
STING were not linked to its ability to regulate basal expression of IFN-stimulated genes, activate transcription, or autophagy. Using
vesicular stomatitis virus as a model, we identified a requirement of
STING to inhibit translation during
infection and upon transfection of synthetic RLR
ligands. This inhibition occurs at the level of translation initiation and restricts the production of viral and host
proteins. The inability to restrict translation rendered
STING-deficient cells 100 times more likely to support productive
viral infections than wild-type counterparts. Genetic analysis linked
RNA sensing by RLRs to
STING-dependent translation inhibition, independent of MAVS. Thus,
STING has dual functions in host defense, regulating
protein synthesis to prevent
RNA virus infection and regulating IFN expression to restrict DNA viruses.