scholarly journals Rinderpest Virus Blocks Type I and Type II Interferon Action: Role of Structural and Nonstructural Proteins

2006 ◽  
Vol 80 (15) ◽  
pp. 7555-7568 ◽  
Author(s):  
Sambit K. Nanda ◽  
Michael D. Baron
Keyword(s):  
Virus Infection ◽  
Viral Protein ◽  
Measles Virus ◽  
Nuclear Translocation ◽  
Nonstructural Protein ◽  
Type I ◽  
Type Ii ◽  
Rinderpest Virus ◽  
V Protein ◽  
Infected Cells

ABSTRACT Rinderpest virus (RPV) is a paramyxovirus closely related to the human pathogen Measles virus. It causes severe disease in cattle, buffalo, and some wild animals; although it can infect humans, it does not cause disease. Here, we demonstrate that RPV blocks the action of both type I (α) and type II (γ) interferons (IFNs) by blocking the phosphorylation and nuclear translocation of STAT1 and STAT2 and that this block is not related to species specificity. In addition, both wild-type virulent and vaccine strains of the virus blocked IFN action. Unlike the case with some other paramyxoviruses, neither STAT1 nor STAT2 is degraded upon virus infection. STAT1 is bound by both the viral structural protein P, and thereby recruited to concentrations of viral protein in the cell, and the nonstructural protein V. Although both P and V proteins bind to STAT1 and can block IFN action when expressed in transfected cells, the IFN antagonist activity of the P protein is weaker than that of the V protein. The viral C protein also seems to weakly block IFN-induced activation of STAT1 in transfection experiments. However, studies with knockout viruses showed that the viral V protein appears to be the dominant inhibitor of IFN signaling in the context of virus infection, since prevention of viral V expression restored the IFN sensitivity of infected cells. Although a change in the distribution pattern of STAT2 was observed in virus-infected cells, STAT2 was not bound by any viral protein.

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 Regulation of the Ebola Virus VP24 Protein by SUMO

2019 ◽  
Vol 94 (1) ◽  
Author(s):  
Santiago Vidal ◽  
Ahmed El Motiam ◽  
Rocío Seoane ◽  
Viktorija Preitakaite ◽  
Yanis Hichem Bouzaher ◽  
...  
Keyword(s):  
Immune Response ◽  
Innate Immune Response ◽  
Viral Protein ◽  
Matrix Protein ◽  
Ebola Virus ◽  
Nuclear Translocation ◽  
Critical Role ◽  
Innate Immune ◽  
Type I ◽  
Negative Modulator

ABSTRACT Some viruses take advantage of conjugation of ubiquitin or ubiquitin-like proteins to enhance their own replication. One example is Ebola virus, which has evolved strategies to utilize these modification pathways to regulate the viral proteins VP40 and VP35 and to counteract the host defenses. Here, we show a novel mechanism by which Ebola virus exploits the ubiquitin and SUMO pathways. Our data reveal that minor matrix protein VP24 of Ebola virus is a bona fide SUMO target. Analysis of a SUMOylation-defective VP24 mutant revealed a reduced ability to block the type I interferon (IFN) pathway and to inhibit IFN-mediated STAT1 nuclear translocation, exhibiting a weaker interaction with karyopherin 5 and significantly diminished stability. Using glutathione S-transferase (GST) pulldown assay, we found that VP24 also interacts with SUMO in a noncovalent manner through a SIM domain. Mutation of the SIM domain in VP24 resulted in a complete inability of the protein to downmodulate the IFN pathway and in the monoubiquitination of the protein. We identified SUMO deubiquitinating enzyme ubiquitin-specific-processing protease 7 (USP7) as an interactor and a negative modulator of VP24 ubiquitination. Finally, we show that mutation of one ubiquitination site in VP24 potentiates the IFN modulatory activity of the viral protein and its ability to block IFN-mediated STAT1 nuclear translocation, pointing to the ubiquitination of VP24 as a negative modulator of the VP24 activity. Altogether, these results indicate that SUMO interacts with VP24 and promotes its USP7-mediated deubiquitination, playing a key role in the interference with the innate immune response mediated by the viral protein. IMPORTANCE The Ebola virus VP24 protein plays a critical role in escape of the virus from the host innate immune response. Therefore, deciphering the molecular mechanisms modulating VP24 activity may be useful to identify potential targets amenable to therapeutics. Here, we identify the cellular proteins USP7, SUMO, and ubiquitin as novel interactors and regulators of VP24. These interactions may represent novel potential targets to design new antivirals with the ability to modulate Ebola virus replication.

scholarly journals Porcine Reproductive and Respiratory Syndrome Virus Inhibits Type I Interferon Signaling by Blocking STAT1/STAT2 Nuclear Translocation

2010 ◽  
Vol 84 (21) ◽  
pp. 11045-11055 ◽  
Author(s):  
Deendayal Patel ◽  
Yuchen Nan ◽  
Meiyan Shen ◽  
Krit Ritthipichai ◽  
Xiaoping Zhu ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Viral Infections ◽  
Nuclear Translocation ◽  
Type I Interferons ◽  
Respiratory Syndrome Virus ◽  
Detectable Effect ◽  
Type I ◽  
Live Virus ◽  
Type I Ifns ◽  
Infected Cells

ABSTRACT Type I interferons (IFNs) IFN-α/β play an important role in innate immunity against viral infections by inducing antiviral responses. Porcine reproductive and respiratory syndrome virus (PRRSV) inhibits the synthesis of type I IFNs. However, whether PRRSV can inhibit IFN signaling is less well understood. In the present study, we found that PRRSV interferes with the IFN signaling pathway. The transcript levels of IFN-stimulated genes ISG15 and ISG56 and protein level of signal transducer and activator of transcription 2 (STAT2) in PRRSV VR2385-infected MARC-145 cells were significantly lower than those in mock-infected cells after IFN-α treatment. IFN-induced phosphorylation of both STAT1 and STAT2 and their heterodimer formation in the PRRSV-infected cells were not affected. However, the majority of the STAT1/STAT2/IRF9 (IFN regulatory factor 9) heterotrimers remained in the cytoplasm of PRRSV-infected cells, which indicates that the nuclear translocation of the heterotrimers was blocked. Overexpression of NSP1β of PRRSV VR2385 inhibited expression of ISG15 and ISG56 and blocked nuclear translocation of STAT1, which suggests that NSP1β might be the viral protein responsible for the inhibition of IFN signaling. PRRSV infection in primary porcine pulmonary alveolar macrophages (PAMs) also inhibited IFN-α-stimulated expression of the ISGs and the STAT2 protein. In contrast, a licensed low-virulence vaccine strain, Ingelvac PRRS modified live virus (MLV), activated expression of IFN-inducible genes, including those of chemokines and antiviral proteins, in PAMs without the addition of external IFN and had no detectable effect on IFN signaling. These findings suggest that PRRSV interferes with the activation and signaling pathway of type I IFNs by blocking ISG factor 3 (ISGF3) nuclear translocation.

scholarly journals Rotavirus inhibits IFN-induced STAT nuclear translocation by a mechanism that acts after STAT binding to importin-α

2014 ◽  
Vol 95 (8) ◽  
pp. 1723-1733 ◽  
Author(s):  
Gavan Holloway ◽  
Vi T. Dang ◽  
David A. Jans ◽  
Barbara S. Coulson
Keyword(s):  
Nuclear Export ◽  
Nuclear Translocation ◽  
Strain Analysis ◽  
Nuclear Accumulation ◽  
Type I ◽  
Group A Rotaviruses ◽  
Importin Α ◽  
Group A ◽  
Infected Cells ◽  
Novel Strategy

The importance of innate immunity to rotaviruses is exemplified by the range of strategies evolved by rotaviruses to interfere with the IFN response. We showed previously that rotaviruses block gene expression induced by type I and II IFNs, through a mechanism allowing activation of signal transducer and activator of transcription (STAT) 1 and STAT2 but preventing their nuclear accumulation. This normally occurs through activated STAT1/2 dimerization, enabling an interaction with importin α5 that mediates transport into the nucleus. In rotavirus-infected cells, STAT1/2 inhibition may limit the antiviral actions of IFN produced early in infection. Here we further analysed the block to STAT1/2 nuclear accumulation, showing that activated STAT1 accumulates in the cytoplasm in rotavirus-infected cells. STAT1/2 nuclear accumulation was inhibited by rotavirus even in the presence of the nuclear export inhibitor Leptomycin B, demonstrating that enhanced nuclear export is not involved in STAT1/2 cytoplasmic retention. The ability to inhibit STAT nuclear translocation was completely conserved amongst the group A rotaviruses tested, including a divergent avian strain. Analysis of mutant rotaviruses indicated that residues after amino acid 47 of NSP1 are dispensable for STAT inhibition. Furthermore, expression of any of the 12 Rhesus monkey rotavirus proteins did not inhibit IFN-stimulated STAT1 nuclear translocation. Finally, co-immunoprecipitation experiments from transfected epithelial cells showed that STAT1/2 binds importin α5 normally following rotavirus infection. These findings demonstrate that rotavirus probably employs a novel strategy to inhibit IFN-induced STAT signalling, which acts after STAT activation and binding to the nuclear import machinery.

scholarly journals Chicken cGAS Senses Fowlpox Virus Infection and Regulates Macrophage Effector Functions

2021 ◽  
Vol 11 ◽  
Author(s):  
Marisa Oliveira ◽  
Damaris Ribeiro Rodrigues ◽  
Vanaique Guillory ◽  
Emmanuel Kut ◽  
Efstathios S. Giotis ◽  
...  
Keyword(s):  
Virus Infection ◽  
Adaptor Protein ◽  
Type I Interferons ◽  
Type I ◽  
Fowlpox Virus ◽  
Effector Functions ◽  
Mhc Ii ◽  
Infected Cells ◽  
Sting Pathway ◽  
Multiple Species

The anti-viral immune response is dependent on the ability of infected cells to sense foreign nucleic acids. In multiple species, the pattern recognition receptor (PRR) cyclic GMP-AMP synthase (cGAS) senses viral DNA as an essential component of the innate response. cGAS initiates a range of signaling outputs that are dependent on generation of the second messenger cGAMP that binds to the adaptor protein stimulator of interferon genes (STING). Here we show that in chicken macrophages, the cGAS/STING pathway is essential not only for the production of type-I interferons in response to intracellular DNA stimulation, but also for regulation of macrophage effector functions including the expression of MHC-II and co-stimulatory molecules. In the context of fowlpox, an avian DNA virus infection, the cGAS/STING pathway was found to be responsible for type-I interferon production and MHC-II transcription. The sensing of fowlpox virus DNA is therefore essential for mounting an anti-viral response in chicken cells and for regulation of a specific set of macrophage effector functions.

scholarly journals Epstein-Barr Virus (EBV) Tegument Protein BGLF2 Suppresses Type I Interferon Signaling To Promote EBV Reactivation

2020 ◽  
Vol 94 (11) ◽  
Author(s):  
XueQiao Liu ◽  
Tomohiko Sadaoka ◽  
Tammy Krogmann ◽  
Jeffrey I. Cohen
Keyword(s):  
Virus Infection ◽  
Type I Interferon ◽  
Tegument Protein ◽  
Type I ◽  
Type I Ifn ◽  
Virus Reactivation ◽  
Ebv Infection ◽  
Ebv Reactivation ◽  
Stat3 Phosphorylation ◽  
Infected Cells

ABSTRACT Interferon alpha (IFN-α) and IFN-β are type I IFNs that are induced by virus infection and are important in the host’s innate antiviral response. EBV infection activates multiple cell signaling pathways, resulting in the production of type I IFN which inhibits EBV infection and virus-induced B-cell transformation. We reported previously that EBV tegument protein BGLF2 activates p38 and enhances EBV reactivation. To further understand the role of BGLF2 in EBV infection, we used mass spectrometry to identify cellular proteins that interact with BGLF2. We found that BGLF2 binds to Tyk2 and confirmed this interaction by coimmunoprecipitation. BGLF2 blocked type I IFN-induced Tyk2, STAT1, and STAT3 phosphorylation and the expression of IFN-stimulated genes (ISGs) IRF1, IRF7, and MxA. In contrast, BGLF2 did not inhibit STAT1 phosphorylation induced by IFN-γ. Deletion of the carboxyl-terminal 66 amino acids of BGLF2 reduced the ability of the protein to repress type I IFN signaling. Treatment of gastric carcinoma and Raji cells with IFN-α blocked BZLF1 expression and EBV reactivation; however, expression of BGLF2 reduced the ability of IFN-α to inhibit BZLF1 expression and enhanced EBV reactivation. In summary, EBV BGLF2 interacts with Tyk2, inhibiting Tyk2, STAT1, and STAT3 phosphorylation and impairs type I IFN signaling; BGLF2 also counteracts the ability of IFN-α to suppress EBV reactivation. IMPORTANCE Type I interferons are important for controlling virus infection. We have found that the Epstein-Barr virus (EBV) BGLF2 tegument protein binds to a protein in the type I interferon signaling pathway Tyk2 and inhibits the expression of genes induced by type I interferons. Treatment of EBV-infected cells with type I interferon inhibits reactivation of the virus, while expression of EBV BGLF2 reduces the ability of type I interferon to inhibit virus reactivation. Thus, a tegument protein delivered to cells during virus infection inhibits the host’s antiviral response and promotes virus reactivation of latently infected cells. Therefore, EBV BGLF2 might protect virus-infected cells from the type I interferon response in cells undergoing lytic virus replication.

scholarly journals Type I interferons are essential while type II interferon is dispensable for protection against St. Louis encephalitis virus infection in the mouse brain

Virulence ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 244-259
Author(s):  
Rebeca Froes Rocha ◽  
Juliana L. Del Sarto ◽  
Giovanni F. Gomes ◽  
Mariana P. Gonçalves ◽  
Milene A. Rachid ◽  
...  
Keyword(s):  
Virus Infection ◽  
Mouse Brain ◽  
Encephalitis Virus ◽  
Type I Interferons ◽  
Type I ◽  
Type Ii

scholarly journals Mechanism of mda-5 Inhibition by Paramyxovirus V Proteins

2008 ◽  
Vol 83 (3) ◽  
pp. 1465-1473 ◽  
Author(s):  
K. S. Childs ◽  
J. Andrejeva ◽  
R. E. Randall ◽  
S. Goodbourn
Keyword(s):  
Helicase Domain ◽  
Type I ◽  
Rna Helicases ◽  
V Protein ◽  
Rna Molecules ◽  
Cytoplasmic Rna ◽  
Dsrna Binding ◽  
Infected Cells ◽  
Self Association ◽  
Inducible Gene

ABSTRACT The RNA helicases encoded by melanoma differentiation-associated gene 5 (mda-5) and retinoic acid-inducible gene I (RIG-I) detect foreign cytoplasmic RNA molecules generated during the course of a virus infection, and their activation leads to induction of type I interferon synthesis. Paramyxoviruses limit the amount of interferon produced by infected cells through the action of their V protein, which binds to and inhibits mda-5. Here we show that activation of both mda-5 and RIG-I by double-stranded RNA (dsRNA) leads to the formation of homo-oligomers through self-association of the helicase domains. We identify a region within the helicase domain of mda-5 that is targeted by all paramyxovirus V proteins and demonstrate that they inhibit activation of mda-5 by blocking dsRNA binding and consequent self-association. In addition to this commonly targeted domain, some paramyxovirus V proteins target additional regions of mda-5. In contrast, V proteins cannot bind to RIG-I and consequently have no effect on the ability of RIG-I to bind dsRNA or to form oligomers.

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