scholarly journals SARS-CoV-2 Nucleocapsid Protein Interacts with RIG-I and Represses RIG-Mediated IFN-β Production

Viruses ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 47
Author(s):  
Keli Chen ◽  
Feng Xiao ◽  
Dingwen Hu ◽  
Weiwei Ge ◽  
Mingfu Tian ◽  
...  
Keyword(s):  
Sendai Virus ◽  
Initial Step ◽  
Poly I:C ◽  
Type I ◽  
Rna Recognition ◽  
Highly Pathogenic ◽  
N Protein ◽  
Immune Pathway ◽  
Innate Immune Pathway ◽  
Recognition Receptor

SARS-CoV-2 is highly pathogenic in humans and poses a great threat to public health worldwide. Clinical data shows a disturbed type I interferon (IFN) response during the virus infection. In this study, we discovered that the nucleocapsid (N) protein of SARS-CoV-2 plays an important role in the inhibition of interferon beta (IFN-β) production. N protein repressed IFN-β production induced by poly(I:C) or upon Sendai virus (SeV) infection. We noted that N protein also suppressed IFN-β production, induced by several signaling molecules downstream of the retinoic acid-inducible gene I (RIG-I) pathway, which is the crucial pattern recognition receptor (PRR) responsible for identifying RNA viruses. Moreover, our data demonstrated that N protein interacted with the RIG-I protein through the DExD/H domain, which has ATPase activity and plays an important role in the binding of immunostimulatory RNAs. These results suggested that SARS-CoV-2 N protein suppresses the IFN-β response through targeting the initial step, potentially the cellular PRR–RNA-recognition step in the innate immune pathway. Therefore, we propose that the SARS-CoV-2 N protein represses IFN-β production by interfering with RIG-I.

scholarly journals SARS-CoV-2 Nucleocapsid Protein Targets RIG-I-Like Receptor Pathways to Inhibit the Induction of Interferon Response

Cells ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 530
Author(s):  
Soo Jin Oh ◽  
Ok Sarah Shin
Keyword(s):  
Nucleocapsid Protein ◽  
Nuclear Translocation ◽  
Nonstructural Protein ◽  
Poly I:C ◽  
Interferon Response ◽  
Type I ◽  
Antiviral Immune Response ◽  
N Protein ◽  
Nonstructural Protein 1 ◽  
Polycytidylic Acid

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the coronavirus disease 2019 (COVID-19) that has resulted in the current pandemic. The lack of highly efficacious antiviral drugs that can manage this ongoing global emergency gives urgency to establishing a comprehensive understanding of the molecular pathogenesis of SARS-CoV-2. We characterized the role of the nucleocapsid protein (N) of SARS-CoV-2 in modulating antiviral immunity. Overexpression of SARS-CoV-2 N resulted in the attenuation of retinoic acid inducible gene-I (RIG-I)-like receptor-mediated interferon (IFN) production and IFN-induced gene expression. Similar to the SARS-CoV-1 N protein, SARS-CoV-2 N suppressed the interaction between tripartate motif protein 25 (TRIM25) and RIG-I. Furthermore, SARS-CoV-2 N inhibited polyinosinic: polycytidylic acid [poly(I:C)]-mediated IFN signaling at the level of Tank-binding kinase 1 (TBK1) and interfered with the association between TBK1 and interferon regulatory factor 3 (IRF3), subsequently preventing the nuclear translocation of IRF3. We further found that both type I and III IFN production induced by either the influenza virus lacking the nonstructural protein 1 or the Zika virus were suppressed by the SARS-CoV-2 N protein. Our findings provide insights into the molecular function of the SARS-CoV-2 N protein with respect to counteracting the host antiviral immune response.

scholarly journals The Severe Acute Respiratory Syndrome Coronavirus Nucleocapsid Inhibits Type I Interferon Production by Interfering with TRIM25-Mediated RIG-I Ubiquitination

2017 ◽  
Vol 91 (8) ◽  
Author(s):  
Yong Hu ◽  
Wei Li ◽  
Ting Gao ◽  
Yan Cui ◽  
Yanwen Jin ◽  
...  
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Type I Interferon ◽  
Sendai Virus ◽  
Innate Immune ◽  
Atypical Pneumonia ◽  
Type I ◽  
Spry Domain ◽  
N Protein ◽  
Host Interaction ◽  
C Terminus

ABSTRACT Severe acute respiratory syndrome (SARS) is a respiratory disease, caused by a coronavirus (SARS-CoV), that is characterized by atypical pneumonia. The nucleocapsid protein (N protein) of SARS-CoV plays an important role in inhibition of type I interferon (IFN) production via an unknown mechanism. In this study, the SARS-CoV N protein was found to bind to the SPRY domain of the tripartite motif protein 25 (TRIM25) E3 ubiquitin ligase, thereby interfering with the association between TRIM25 and retinoic acid-inducible gene I (RIG-I) and inhibiting TRIM25-mediated RIG-I ubiquitination and activation. Type I IFN production induced by poly I·C or Sendai virus (SeV) was suppressed by the SARS-CoV N protein. SARS-CoV replication was increased by overexpression of the full-length N protein but not N amino acids 1 to 361, which could not interact with TRIM25. These findings provide an insightful interpretation of the SARS-CoV-mediated host innate immune suppression caused by the N protein. IMPORTANCE The SARS-CoV N protein is essential for the viral life cycle and plays a key role in the virus-host interaction. We demonstrated that the interaction between the C terminus of the N protein and the SPRY domain of TRIM25 inhibited TRIM25-mediated RIG-I ubiquitination, which resulted in the inhibition of IFN production. We also found that the Middle East respiratory syndrome CoV (MERS-CoV) N protein interacted with TRIM25 and inhibited RIG-I signaling. The outcomes of these findings indicate the function of the coronavirus N protein in modulating the host's initial innate immune response.

scholarly journals Swine Acute Diarrhea Syndrome Coronavirus Nucleocapsid Protein Antagonizes Interferon-β Production via Blocking the Interaction Between TRAF3 and TBK1

2021 ◽  
Vol 12 ◽  
Author(s):  
Zhihai Zhou ◽  
Yuan Sun ◽  
Jingya Xu ◽  
Xiaoyu Tang ◽  
Ling Zhou ◽  
...  
Keyword(s):  
Innate Immunity ◽  
Acute Diarrhea ◽  
Nuclear Translocation ◽  
Sendai Virus ◽  
Type I ◽  
Innate Immune Responses ◽  
N Protein ◽  
Antiviral Innate Immunity ◽  
Diarrhea Syndrome

Swine acute diarrhea syndrome coronavirus (SADS-CoV), first discovered in 2017, is a porcine enteric coronavirus that can cause acute diarrhea syndrome (SADS) in piglets. Here, we studied the role of SADS-CoV nucleocapsid (N) protein in innate immunity. Our results showed that SADS-CoV N protein could inhibit type I interferon (IFN) production mediated by Sendai virus (Sev) and could block the phosphorylation and nuclear translocation of interferon regulatory factor 3 (IRF3). Simultaneously, the IFN-β promoter activity mediated by TANK binding kinase 1 (TBK1) or its upstream molecules in the RLRs signal pathway was inhibited by SADS-CoV N protein. Further investigations revealed that SADS-CoV N protein could counteract interaction between TNF receptor-associated factor 3 (TRAF3) and TBK1, which led to reduced TBK1 activation and IFN-β production. Our study is the first report of the interaction between SADS-CoV N protein and the host antiviral innate immune responses, and the mechanism utilized by SADS-CoV N protein provides a new insight of coronaviruses evading host antiviral innate immunity.

scholarly journals SARS-CoV-2 ORF9b Antagonizes Type I and III Interferons by Targeting Multiple Components of RIG-I/MDA-5-MAVS, TLR3-TRIF, and cGAS-STING Signaling Pathways

2020 ◽  
Author(s):  
Lulu Han ◽  
Meng-Wei Zhuang ◽  
Yi Zheng ◽  
Jing Zhang ◽  
Mei-Ling Nan ◽  
...  
Keyword(s):  
Signaling Pathways ◽  
Sendai Virus ◽  
Active Form ◽  
Adaptor Protein ◽  
Antiviral Immunity ◽  
Clinical Findings ◽  
Etiologic Agent ◽  
Poly I:C ◽  
Type I ◽  
Reading Frame

AbstractSevere acute respiratory syndrome corona-virus 2 (SARS-CoV-2), the etiologic agent of the coronavirus disease 2019 (COVID-19), has a catastrophic effect on human health and society. Clinical findings indicated that the suppression of innate antiviral immunity, especially the type I and III interferon (IFN) production, contributes to the pathogenesis of COVID-19. However, how SARS-CoV-2 evades antiviral immunity still needs further investigations. Here, we reported that the open reading frame 9b (ORF9b) protein encoded by the SARS-CoV-2 genome inhibits the activation of type I and III IFN response by targeting multiple molecules of innate antiviral signaling pathways. SARS-CoV-2 ORF9b impaired the induction of type I and III IFNs by Sendai virus or the dsRNA mimic poly (I:C). SARS-CoV-2 ORF9b inhibits the activation of type I and III IFNs induced by the components of cytosolic dsRNA-sensing pathways of RIG-I/MDA5-MAVS signaling, including RIG-I, MDA-5, MAVS, TBK1, and IKKε rather than IRF3-5D, the active form of IRF3. SARS-CoV-2 ORF9b also suppressed the induction of type I and III IFNs by TRIF and STING, the adaptor protein of endosome RNA-sensing pathway of TLR3-TRIF signaling and the adaptor protein of cytosolic DNA-sensing pathway of cGAS-STING signaling, respectively. Mechanistically, SARS-CoV-2 ORF9b protein interacts with RIG-I, MDA-5, MAVS, TRIF, STING, TBK1, and prevents TBK1 phosphorylation, thus impeding the phosphorylation and nuclear trans-localization of IRF3 activation. Overexpression of SARS-CoV-2 ORF9b facilitates the replication of the vesicular stomatitis virus. Therefore, SARS-CoV-2 ORF9b negatively regulates antiviral immunity, thus, facilitate virus replication. This study contributes to our understanding of the molecular mechanism of how SARS-CoV-2 impaired antiviral immunity and providing an essential clue to the pathogenesis of COVID-19.

scholarly journals SARS-CoV-2 nsp12 attenuates type I interferon production by inhibiting IRF3 nuclear translocation

2021 ◽  
Author(s):  
Wenjing Wang ◽  
Zhuo Zhou ◽  
Xia Xiao ◽  
Zhongqin Tian ◽  
Xiaojing Dong ◽  
...  
Keyword(s):  
Nuclear Translocation ◽  
Type I Interferon ◽  
Sendai Virus ◽  
Polymerase Activity ◽  
Poly I:C ◽  
Type I ◽  
Dependent Manner ◽  
Promoter Activation ◽  
Global Pandemic ◽  
Antiviral Innate Immunity

AbstractSARS-CoV-2 is the pathogenic agent of COVID-19, which has evolved into a global pandemic. Compared with some other respiratory RNA viruses, SARS-CoV-2 is a poor inducer of type I interferon (IFN). Here, we report that SARS-CoV-2 nsp12, the viral RNA-dependent RNA polymerase (RdRp), suppresses host antiviral responses. SARS-CoV-2 nsp12 attenuated Sendai virus (SeV)- or poly(I:C)-induced IFN-β promoter activation in a dose-dependent manner. It also inhibited IFN promoter activation triggered by RIG-I, MDA5, MAVS, and IRF3 overexpression. Nsp12 did not impair IRF3 phosphorylation but suppressed the nuclear translocation of IRF3. Mutational analyses suggested that this suppression was not dependent on the polymerase activity of nsp12. Given these findings, our study reveals that SARS-CoV-2 RdRp can antagonize host antiviral innate immunity and thus provides insights into viral pathogenesis.

scholarly journals Feline Infectious Peritonitis Virus Nsp5 Inhibits Type I Interferon Production by Cleaving NEMO at Multiple Sites

Viruses ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 43 ◽  
Author(s):  
Si Chen ◽  
Jin Tian ◽  
Zhijie Li ◽  
Hongtao Kang ◽  
Jikai Zhang ◽  
...  
Keyword(s):  
Type I Interferon ◽  
Sendai Virus ◽  
Nuclear Factor Κb ◽  
Poly I:C ◽  
Type I ◽  
Dependent Manner ◽  
Type I Ifn ◽  
Feline Infectious Peritonitis Virus ◽  
Feline Infectious Peritonitis ◽  
Polycytidylic Acid

Feline infectious peritonitis (FIP), caused by virulent feline coronavirus, is the leading infectious cause of death in cats. The type I interferon (type I IFN)-mediated immune responses provide host protection from infectious diseases. Several coronaviruses have been reported to evolve diverse strategies to evade host IFN response. However, whether feline infectious peritonitis virus (FIPV) antagonizes the type I IFN signaling remains unclear. In this study, we demonstrated that FIPV strain DF2 infection not only failed to induce interferon-β (IFN-β) and interferon-stimulated gene (ISG) production, but also inhibited Sendai virus (SEV) or polyinosinic-polycytidylic acid (poly(I:C))-induced IFN-β production. Subsequently, we found that one of the non-structural proteins encoded by the FIPV genome, nsp5, interrupted type I IFN signaling in a protease-dependent manner by cleaving the nuclear factor κB (NF-κB) essential modulator (NEMO) at three sites—glutamine132 (Q132), Q205, and Q231. Further investigation revealed that the cleavage products of NEMO lost the ability to activate the IFN-β promoter. Mechanistically, the nsp5-mediated NEMO cleavage disrupted the recruitment of the TRAF family member-associated NF-κB activator (TANK) to NEMO, which reduced the phosphorylation of interferon regulatory factor 3 (IRF3), leading to the inhibition of type I IFN production. Our research provides new insights into the mechanism for FIPV to counteract host innate immune response.

scholarly journals JMJD6 negatively regulates cytosolic RNA induced antiviral signaling by recruiting RNF5 to promote activated IRF3 K48 ubiquitination

2021 ◽  
Vol 17 (3) ◽  
pp. e1009366
Author(s):  
Wei Zhang ◽  
Qi Wang ◽  
Fan Yang ◽  
Zixiang Zhu ◽  
Yueyue Duan ◽  
...  
Keyword(s):  
Immune Responses ◽  
Type I Interferon ◽  
Sendai Virus ◽  
Rna Virus ◽  
Negative Regulator ◽  
Viral Rna ◽  
Poly I:C ◽  
Type I ◽  
Dependent Manner ◽  
Antiviral Signaling

The negative regulation of antiviral immune responses is essential for the host to maintain homeostasis. Jumonji domain-containing protein 6 (JMJD6) was previously identified with a number of functions during RNA virus infection. Upon viral RNA recognition, retinoic acid-inducible gene-I-like receptors (RLRs) physically interact with the mitochondrial antiviral signaling protein (MAVS) and activate TANK-binding kinase 1 (TBK1) to induce type-I interferon (IFN-I) production. Here, JMJD6 was demonstrated to reduce type-I interferon (IFN-I) production in response to cytosolic poly (I:C) and RNA virus infections, including Sendai virus (SeV) and Vesicular stomatitis virus (VSV). Genetic inactivation of JMJD6 enhanced IFN-I production and impaired viral replication. Our unbiased proteomic screen demonstrated JMJD6 contributes to IRF3 K48 ubiquitination degradation in an RNF5-dependent manner. Mice with gene deletion of JMJD6 through piggyBac transposon-mediated gene transfer showed increased VSV-triggered IFN-I production and reduced susceptibility to the virus. These findings classify JMJD6 as a negative regulator of the host’s innate immune responses to cytosolic viral RNA.

scholarly journals Crosstalk Between Apoptosis and Autophagy: Environmental Genotoxins, Infection, and Innate Immunity

2017 ◽  
Vol 10 ◽  
pp. 117967071668508 ◽  
Author(s):  
Michael G Kemp
Keyword(s):  
Type I Interferons ◽  
Health Concern ◽  
Type I ◽  
Environmental Carcinogens ◽  
Disease Symptoms ◽  
Cyclic Dinucleotides ◽  
Genetic And Environmental Factors ◽  
Immune Pathway ◽  
Innate Immune Pathway

Autoimmune disorders constitute a major and growing health concern. However, the genetic and environmental factors that contribute to or exacerbate disease symptoms remain unclear. Type I interferons (IFNs) are known to break immune tolerance and be elevated in the serum of patients with autoimmune diseases such as lupus. Extensive work over the past decade has characterized the role of a protein termed stimulator of interferon genes, or STING, in mediating IFN expression and activation in response to cytosolic DNA and cyclic dinucleotides. Interestingly, this STING-dependent innate immune pathway both utilizes and is targeted by the cell’s autophagic machinery. Given that aberrant interplay between the apoptotic and autophagic machineries contributes to deregulation of the STING-dependent pathway, IFN-regulated autoimmune phenotypes may be influenced by the combined exposure to environmental carcinogens and pathogenic microorganisms and viruses. This review therefore summarizes recent data regarding these important issues in the field of autoimmunity.

scholarly journals Middle East Respiratory Syndrome Coronavirus Nucleocapsid Protein Suppresses Type I and Type III Interferon Induction by Targeting RIG-I Signaling

2020 ◽  
Vol 94 (13) ◽  
Author(s):  
Chi-You Chang ◽  
Helene Minyi Liu ◽  
Ming-Fu Chang ◽  
Shin C. Chang
Keyword(s):  
Immune Response ◽  
Promoter Activity ◽  
Sendai Virus ◽  
Ectopic Expression ◽  
Host Immune Response ◽  
Type I ◽  
Mrna Levels ◽  
N Protein ◽  
Type Iii ◽  
Type Iii Ifn

ABSTRACT Type I and type III interferons (IFNs) are the frontline of antiviral defense mechanisms that trigger hundreds of downstream antiviral genes. In this study, we observed that MERS-CoV nucleocapsid (N) protein suppresses type I and type III IFN gene expression. The N protein suppresses Sendai virus-induced IFN-β and IFN-λ1 by reducing their promoter activity and mRNA levels, as well as downstream IFN-stimulated genes (ISGs). Retinoic acid-inducible gene I (RIG-I) is known to recognize viral RNA and induce IFN expression through tripartite motif-containing protein 25 (TRIM25)-mediated ubiquitination of RIG-I caspase activation and recruitment domains (CARDs). We discovered that MERS-CoV N protein suppresses RIG-I-CARD-induced, but not MDA5-CARD-induced, IFN-β and IFN-λ1 promoter activity. By interacting with TRIM25, N protein impedes RIG-I ubiquitination and activation and inhibits the phosphorylation of transcription factors IFN-regulatory factor 3 (IRF3) and NF-κB that are known to be important for IFN gene activation. By employing a recombinant Sindbis virus-EGFP replication system, we showed that viral N protein downregulated the production of not only IFN mRNA but also bioactive IFN proteins. Taken together, MERS-CoV N protein functions as an IFN antagonist. It suppresses RIG-I-induced type I and type III IFN production by interfering with TRIM25-mediated RIG-I ubiquitination. Our study sheds light on the pathogenic mechanism of how MERS-CoV causes disease. IMPORTANCE MERS-CoV causes death of about 35% of patients. Published studies showed that some coronaviruses are capable of suppressing interferon (IFN) expression in the early phase of infection and MERS-CoV proteins can modulate host immune response. In this study, we demonstrated that MERS-CoV nucleocapsid (N) protein suppresses the production of both type I and type III IFNs via sequestering TRIM25, an E3 ubiquitin ligase that is essential for activating the RIG-I signaling pathway. Ectopic expression of TRIM25 rescues the suppressive effect of the N protein. In addition, the C-terminal domain of the viral N protein plays a pivotal role in the suppression of IFN-β promoter activity. Our findings reveal how MERS-CoV evades innate immunity and provide insights into the interplay between host immune response and viral pathogenicity.

scholarly journals A Single Amino Acid Substitution within the Paramyxovirus Sendai Virus Nucleoprotein Is a Critical Determinant for Production of Interferon-Beta-Inducing Copyback-Type Defective Interfering Genomes

2017 ◽  
Vol 92 (5) ◽  
Author(s):  
Asuka Yoshida ◽  
Ryoko Kawabata ◽  
Tomoyuki Honda ◽  
Kouji Sakai ◽  
Yasushi Ami ◽  
...  
Keyword(s):  
Innate Immunity ◽  
Amino Acid ◽  
Amino Acid Substitution ◽  
Interferon Beta ◽  
Sendai Virus ◽  
Single Amino Acid Substitution ◽  
Single Amino Acid ◽  
Type I ◽  
N Protein ◽  
Viral Stock

ABSTRACTOne of the first defenses against infecting pathogens is the innate immune system activated by cellular recognition of pathogen-associated molecular patterns (PAMPs). Although virus-derived RNA species, especially copyback (cb)-type defective interfering (DI) genomes, have been shown to serve as real PAMPs, which strongly induce interferon-beta (IFN-β) during mononegavirus infection, the mechanisms underlying DI generation remain unclear. Here, for the first time, we identified a single amino acid substitution causing production of cbDI genomes by successful isolation of two distinct types of viral clones with cbDI-producing and cbDI-nonproducing phenotypes from the stock Sendai virus (SeV) strain Cantell, which has been widely used in a number of studies on antiviral innate immunity as a representative IFN-β-inducing virus. IFN-β induction was totally dependent on the presence of a significant amount of cbDI genome-containing viral particles (DI particles) in the viral stock, but not on deficiency of the IFN-antagonistic viral accessory proteins C and V. Comparison of the isolates indicated that a single amino acid substitution found within the N protein of the cbDI-producing clone was enough to cause the emergence of DI genomes. The mutated N protein of the cbDI-producing clone resulted in a lower density of nucleocapsids than that of the DI-nonproducing clone, probably causing both production of the DI genomes and their formation of a stem-loop structure, which serves as an ideal ligand for RIG-I. These results suggested that the integrity of mononegaviral nucleocapsids might be a critical factor in avoiding the undesirable recognition of infection by host cells.IMPORTANCEThe type I interferon (IFN) system is a pivotal defense against infecting RNA viruses that is activated by sensing viral RNA species. RIG-I is a major sensor for infection with most mononegaviruses, and copyback (cb)-type defective interfering (DI) genomes have been shown to serve as strong RIG-I ligands in real infections. However, the mechanism underlying production of cbDI genomes remains unclear, although DI genomes emerge as the result of an error during viral replication with high doses of viruses. Sendai virus has been extensively studied and is unique in that its interaction with innate immunity reveals opposing characteristics, such as high-level IFN-β induction and strong inhibition of type I IFN pathways. Our findings provide novel insights into the mechanism of production of mononegaviral cbDI genomes, as well as virus-host interactions during innate immunity.

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