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Updated: Jul 11, 2025
Dissecting Innate Immune Signaling in Viral Evasion of Cytokine Production
Published on: March 2, 2014
Early enterovirus translation deficits extend viral RNA replication and elicit sustained MDA5-directed innate
Mikhail I Dobrikov1, Elena Y Dobrikova1, Dasean T Nardone-White1,2
1Department of Neurosurgery, Duke University Medical School, Durham, North Carolina, USA.
Importance:
Multiple pattern recognition receptors sense vRNAs and initiate downstream innate signaling: endosomal Toll-like receptors (TLRs) 3, 7, and 8 and cytoplasmic RIG-I-like receptors (RLRs) RIG-I, and MDA5. They engage distinct signaling scaffolds: mitochondrial antiviral signaling protein (RLR), MyD88, and TLR-adaptor interacting with SLC15A4 on the lysosome (TLR7 and TLR8) and toll/IL-1R domain-containing adaptor inducing IFN (TLR3). By virtue of their unusual vRNA structure and direct host cell entry path, the innate response to EVs uniquely is orchestrated by MDA5. We reported that PVSRIPO's profound attenuation and loss of cytopathogenicity triggers MDA5-directed polar TBK1-IRF3 signaling that generates priming of polyfunctional antitumor CD8+ T-cell responses and durable antitumor surveillance in vivo. Here we unraveled EV-host relations that control suppression of host type-I IFN responses and show that PVSRIPO's deficient immediate host eIF4G cleavage generates unopposed MDA5-directed downstream signaling cascades resulting in sustained type-I IFN release.
Insights
PVSRIPO, a modified enterovirus, enhances antitumor CD8+ T-cell responses by activating MDA5 signaling. This leads to sustained type-I interferon release, improving antitumor surveillance.
Area of Science:
- Immunology
- Virology
- Molecular Biology
Background:
- Pattern recognition receptors like TLRs and RLRs initiate innate immune signaling upon sensing viral RNA (vRNA).
- Distinct signaling scaffolds mediate TLR and RLR pathways, influencing downstream immune responses.
- Enteroviruses (EVs) uniquely engage MDA5 due to their vRNA structure and entry mechanism.
Purpose of the Study:
- To investigate how PVSRIPO, an attenuated enterovirus, modulates host innate immune responses.
- To elucidate the mechanisms controlling type-I interferon suppression by EVs.
- To understand the role of eIF4G cleavage in MDA5-directed signaling.
Main Methods:
- Analysis of innate immune signaling pathways activated by PVSRIPO.
- Investigation of host-EV interactions affecting type-I interferon production.
- Assessment of MDA5-directed signaling cascades and their impact on T-cell responses.
Main Results:
- PVSRIPO triggers MDA5-directed TBK1-IRF3 signaling, priming antitumor CD8+ T-cell responses and in vivo surveillance.
- Deficient immediate host eIF4G cleavage by PVSRIPO leads to unopposed MDA5 signaling.
- Sustained type-I interferon release is observed due to this signaling cascade.
Conclusions:
- PVSRIPO's attenuation strategy involves manipulating host eIF4G cleavage to enhance MDA5-mediated innate immunity.
- This leads to robust, polyfunctional antitumor T-cell responses and durable surveillance.
- Understanding these EV-host interactions offers insights into novel immunotherapy strategies.
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