Unlabelled: Hepatitis C virus (HCV) infection blocks cellular interferon (IFN)-mediated antiviral signaling through cleavage of Cardif by HCV-NS3/4A serine protease. Like NS3/4A, NS4B protein strongly blocks IFN-β production signaling mediated by retinoic acid-inducible gene I (RIG-I); however, the underlying molecular mechanisms are not well understood. Recently, the stimulator of interferon genes (STING) was identified as an activator of RIG-I signaling. STING possesses a structural homology domain with flaviviral NS4B, which suggests a direct protein-protein interaction. In the present study, we investigated the molecular mechanisms by which NS4B targets RIG-I-induced and STING-mediated IFN-β production signaling. IFN-β promoter reporter assay showed that IFN-β promoter activation induced by RIG-I or Cardif was significantly suppressed by both NS4B and NS3/4A, whereas STING-induced IFN-β activation was suppressed by NS4B but not by NS3/4A, suggesting that NS4B had a distinct point of interaction. Immunostaining showed that STING colocalized with NS4B in the endoplasmic reticulum. Immunoprecipitation and bimolecular fluorescence complementation (BiFC) assays demonstrated that NS4B specifically bound STING. Intriguingly, NS4B expression blocked the protein interaction between STING and Cardif, which is required for robust IFN-β activation. NS4B truncation assays showed that its N terminus, containing the STING homology domain, was necessary for the suppression of IFN-β promoter activation. NS4B suppressed residual IFN-β activation by an NS3/4A-cleaved Cardif (Cardif1-508), suggesting that NS3/4A and NS4B may cooperate in the blockade of IFN-β production.
Conclusion: NS4B suppresses RIG-I-mediated IFN-β production signaling through a direct protein interaction with STING. Disruption of that interaction may restore cellular antiviral responses and may constitute a novel therapeutic strategy for the eradication of HCV.
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http://dx.doi.org/10.1002/hep.26017 | DOI Listing |
bioRxiv
January 2025
Center for Retrovirus Research, The Ohio State University, Columbus, OH 43210, USA.
Zika virus (ZIKV) infection can lead to a variety of clinical outcomes, including severe congenital abnormalities. The phosphatidylserine (PS) receptors AXL and TIM-1 are recognized as critical entry factors for ZIKV . However, it remains unclear if and how ZIKV regulates these receptors during infection.
View Article and Find Full Text PDFJ Virol
December 2024
1Division of Gastroenterology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, USA.
Flaviviruses utilize the cellular endoplasmic reticulum (ER) for all aspects of their lifecycle. Genome replication and other viral activities take place in structures called replication organelles (ROs), which are invaginations induced in the ER membrane. Among the required elements for RO formation is the biogenesis of viral nonstructural proteins NS4A and NS4B.
View Article and Find Full Text PDFFront Cell Infect Microbiol
November 2024
Department of Infectious Diseases, The First People's Hospital of Kashi Prefecture, Kashi, China.
Introduction: The hepatitis C virus (HCV) poses a major global health challenge, with its non-structural proteins being essential for viral replication and pathogenesis. Mutations in these proteins significantly contribute to drug resistance, necessitating innovative therapeutic strategies. This study aims to identify epitope-based therapeutic targets in the non-structural proteins of HCV genotype 1, employing in-depth in silico tools to counteract emerging drug resistance.
View Article and Find Full Text PDFBiomol NMR Assign
November 2024
Experimental Drug Development Centre, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore.
Zika virus has raised global concerns due to its link to microcephaly and Guillain-Barré syndrome in adults. One of viral nonstructural proteins-NS4B, an integral membrane protein, plays crucial roles in viral replication by interacting with both viral and host proteins, rendering it an attractive drug target for antiviral development. We purified the N-terminal region of ZIKV NS4B (NS4B NTD) and reconstituted it into detergent micelles.
View Article and Find Full Text PDFAntiviral Res
November 2024
College of Veterinary Medicine and Bio-Safety Research Institute, Jeonbuk National University, Iksan, 54596, Republic of Korea. Electronic address:
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