Major Human Cytomegalovirus Structural Protein pp65 (ppUL83) Prevents Interferon Response Factor 3 Activation in the Interferon Response

ABSTRACT We have identified a cytomegalovirus virion protein capable of modulating the rapid induction of an interferon-like response in cells that follows virus binding and penetration. Functional genomics revealed a role for the major cytomegalovirus structural protein, pp65 (ppUL83), in counteracting this response. The underlying mechanism involves a differential impact of this structural protein on the regulation of interferon response factor 3 (IRF-3). In contrast, NF-κB is activated independent of pp65, and neither STAT1 nor STAT3 becomes activated by either virus. pp65 is sufficient to prevent the activation of IRF-3 when introduced alone into cells. pp65 acts by inhibiting nuclear accumulation of IRF-3 and is associated with a reduced IRF-3 phosphorylation state. Thus, this investigation shows that the major structural protein of cytomegalovirus is committed to the modulation of the IRF-3 response, a primary mediator of the type I interferon response. By subverting IRF-3, the virus escapes throwing a central alarm devoted to both immediate antiviral control and regulation of the immune response.

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Modeling PPRV pathogenesis in mice to assess the contribution of innate cells and anti-viral T cells

10.1101/2020.10.27.358309 ◽

2020 ◽

Author(s):

Yashu Sharma ◽

Roman Sarkar ◽

Ayush Jain ◽

Sudhakar Singh ◽

Chander Shekhar ◽

...

Keyword(s):

Animal Model ◽

T Cells ◽

Nk Cells ◽

Immune Cells ◽

Laboratory Animal ◽

Inoculum Size ◽

Interferon Response ◽

Type I ◽

Rapid Induction ◽

The Way

AbstractWe demonstrate a rapid induction of type I IFN response in PPRV stimulated cells and the susceptibility of mice, genetically ablated of interferon response, to PPRV infection. Following PPRV infection, IFNR KO mice gradually reduced their body weights and succumbed to the infection within 10 days. While the infecting inoculum size did not alter the outcome of infection, the nature of the induced disease was qualitatively different. Immunopathological lesions were characterized by the expansion and infiltration of innate immune cells distinctly evident at the lower infecting dose of PPRV infection. The replicating virus particles as well as the viral antigens were abundant in most of the critical organs of PPRV infected IFNR KO mice. Neutrophils and macrophages transported the replicating virus to central nervous system and contributed to pathology while the NK cells and T cells were protective against the virus. Using an array of fluorescently labeled H-2Kb tetramers PPRV specific CD8+ T cells responses were identified and measured in the infected as well as the peptide immunized mice. Our study therefore established and employed a laboratory animal model for investigating PPRV pathogenesis and the contribution of virus specific CD8+ T cells during the virus infection to pave the way for elucidating protective or pathological roles of immune cells during PPRV infection.ImportanceWe developed a laboratory animal model for investigating the pathogenesis and immunity induced by PPRV. IFNR KO animals succumbed to the infection irrespective of the dose and the route of infection. Neutrophils and macrophages served as the Trojan horse and helped transport the virus to CNS to cause encephalitis while the NK cells and CD8+ T cells provided the protection against PPRV infection. We additionally identified class I restricted immunogenic epitopes of PPRV in C57BL/6 mice. Our study therefore paves the way for an optimal utilization of this model to unravel PPRV pathogenesis and assessing the host correlates of protection.

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SARS-CoV-2 non-structural protein 1 inhibits the interferon response by causing depletion of key host signaling factors.

Journal of Virology ◽

10.1128/jvi.00266-21 ◽

2021 ◽

Author(s):

Anil Kumar ◽

Ray Ishida ◽

Tania Strilets ◽

Jamie Cole ◽

Joaquin Lopez-Orozco ◽

...

Keyword(s):

Causative Agent ◽

Interferon Response ◽

Type I ◽

Structural Protein ◽

Type I Ifns ◽

Rapid Spread ◽

Host Signaling ◽

Infected Cells ◽

Serious Disease ◽

Taste And Smell

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is the causative agent of the ongoing COVID-19 pandemic. While previous studies have shown that several SARS-CoV-2 proteins can antagonize the interferon (IFN) response, some of the mechanisms by which they do so are not well understood. In this study, we describe two novel mechanisms by which SARS-CoV-2 blocks the IFN pathway. Type I IFNs and IFN-stimulated genes (ISGs) were poorly induced during SARS-CoV-2 infection and once infection was established, cells were highly resistant to ectopic induction of IFNs and ISGs. Levels of two key IFN signaling pathway components, Tyk2 and STAT2 were significantly lower in SARS-CoV-2 infected cells. Expression of non-structural protein 1 (NSP1) or nucleocapsid in the absence of other viral proteins was sufficient to block IFN induction but only NSP1 was able to inhibit IFN signaling. Mapping studies suggest that NSP1 prevents IFN induction in part by blocking IRF3 phosphorylation. In addition, NSP1-induced depletion of Tyk2 and STAT2 dampened ISG induction. Together, our study provides new insights into how SARS-CoV-2 successfully evades the IFN system to establish infection. Importance SARS-CoV-2 is the causative agent of COVID-19, a serious disease that can have myriad of symptoms from loss of taste and smell to pneumonia and hypercoagulation. The rapid spread of SARS-CoV-2 can be attributed in part to asymptomatic transmission, where infected individuals shed large amounts of virus before the onset of disease. This is likely due to the ability of SARS-CoV-2 to effectively suppress the innate immune system, including the IFN response. Indeed, we show that the IFN response is efficiently blocked during SARS-CoV-2 infection, a process that is mediated in large part by non-structural protein 1 and nucleocapsid. Our study provides new insights on how SARS-CoV-2 evades the IFN response to successfully establish infection. These findings should be considered for the development and administration of therapeutics against SARS-CoV-2.

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DEAD-Box Helicase DDX6 Facilitated RIG-I-Mediated Type-I Interferon Response to EV71 Infection

Frontiers in Cellular and Infection Microbiology ◽

10.3389/fcimb.2021.725392 ◽

2021 ◽

Vol 11 ◽

Author(s):

Rui Zhang ◽

Min Cheng ◽

Bingxin Liu ◽

Meng Yuan ◽

Deyan Chen ◽

...

Keyword(s):

Viral Infection ◽

Type I Interferon ◽

Enterovirus 71 ◽

Antiviral Effect ◽

Host Factors ◽

Interferon Response ◽

Type I ◽

Structural Protein ◽

Rna Helicases ◽

Dead Box

Previous studies have shown that DEAD (Glu-Asp-Ala-Glu)-box RNA helicases play important roles in viral infection, either as cytosolic sensors of pathogenic molecules or as essential host factors against viral infection. In the current study, we found that DDX6, an RNA helicase belonging to the DEAD-box family of helicase, exhibited anti-Enterovirus 71 activity through augmenting RIG-I-mediated type-I IFN response. Moreover, DDX6 binds viral RNA to form an RNA-protein complex to positively regulate the RIG-I-mediated interferon response; however, EV71 has evolved a strategy to antagonize the antiviral effect of DDX6 by proteolytic degradation of the molecule through its non-structural protein 2A, a virus-encoded protease.

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Faculty Opinions recommendation of Major human cytomegalovirus structural protein pp65 (ppUL83) prevents interferon response factor 3 activation in the interferon response.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1022073.251673 ◽

2004 ◽

Author(s):

Grant McFadden

Keyword(s):

Human Cytomegalovirus ◽

Interferon Response ◽

Response Factor ◽

Structural Protein

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Enterovirus A71 2B Inhibits Interferon-Activated JAK/STAT Signaling by Inducing Caspase-3-Dependent Karyopherin-α1 Degradation

Frontiers in Microbiology ◽

10.3389/fmicb.2021.762869 ◽

2021 ◽

Vol 12 ◽

Author(s):

Menghuai Sun ◽

Qian Lin ◽

Chunyang Wang ◽

Jiao Xing ◽

Kunlong Yan ◽

...

Keyword(s):

Innate Immunity ◽

Caspase 3 ◽

Infectious Clone ◽

Underlying Mechanism ◽

Neurological Complications ◽

Type I ◽

Structural Protein ◽

Enterovirus A71 ◽

Stat Signaling ◽

Infected Cells

Enterovirus A71 (EV-A71) is a major pathogen that causes the hand, foot, and mouth disease, which could be fatal with neurological complications in children. The underlying mechanism for the severe pathogenicity remains obscure, but impaired or aberrant innate immunity is considered to play a key role in viral pathogenesis. We reported previously that EV-A71 suppressed type I interferon (IFN) responses by inducing degradation of karyopherin-α1 (KPNA1), a component of the p-STAT1/2 complex. In this report, we showed that 2B, a non-structural protein of EV-A71, was critical to the suppression of the IFN-α-induced type I response in infected cells. Among viral proteins, 2B was the only one that was involved in the degradation of KPNA1, which impeded the formation of the p-STAT1/2/KPNA1 complex and blocked the translocation of p-STAT1/2 into the nucleus upon IFN-α stimulation. Degradation of KPNA1 induced by 2B can be inhibited in the cells pre-treated with Z-DEVD-FMK, a caspase-3 inhibitor, or siRNA targeting caspase-3, indicating that 2B-induced degradation of KPNA1 was caspase-3 dependent. The mechanism by which 2B functioned in the dysregulation of the IFN signaling was analyzed and a putative hydrophilic domain (H1) in the N-terminus of 2B was characterized to be critical for the release of cytochrome c into the cytosol for the activation of pro-caspase-3. We generated an EV-A71 infectious clone (rD1), which was deficient of the H1 domain. In rD1-infected cells, degradation of KPNA1 was relieved and the infected cells were more sensitive to IFN-α, leading to decreased viral replication, in comparison to the cells infected with the virus carrying a full length 2B. Our findings demonstrate that EV-A71 2B protein plays an important role in dysregulating JAK-STAT signaling through its involvement in promoting caspase-3 dependent degradation of KPNA1, which represents a novel strategy employed by EV-A71 to evade host antiviral innate immunity.

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PLASMACYTOID DENDRITIC CELLS FUNCTION IN HIV INFECTION

Clinical & Investigative Medicine ◽

10.25011/cim.v31i4.4808 ◽

2008 ◽

Vol 31 (4) ◽

pp. 13

Author(s):

Martin Hyrcza ◽

Mario Ostrowski ◽

Sandy Der

Keyword(s):

Dendritic Cells ◽

Influenza Virus ◽

Hiv Infection ◽

Gene Transcription ◽

Sendai Virus ◽

Plasmacytoid Dendritic Cells ◽

Type I Interferons ◽

Interferon Response ◽

Type I ◽

Type I Ifn

Plasmacytoid dendritic cells (pDCs) are innate immune cells able to produce large quantities of type I interferons (IFN) when activated. Human immunodeficiency virus (HIV)-infected patients show generalized immune dysfunction characterized in part by chronic interferon response. In this study we investigated the role of dendritic cells inactivating and maintaining this response. Specifically we compared the IFN geneactivity in pDCs in response to several viruses and TLR agonists. We hypothesized that 1) the pattern of IFN gene transcription would differ in pDCs treated with HIV than with other agents, and 2) that pDCs from patients from different stages of disease would respond differently to the stimulations. To test these hypotheses, we obtained pDCs from 15 HIV-infected and uninfected individuals and treated freshly isolated pDCs with either HIV (BAL strain), influenza virus (A/PR/8/34), Sendai virus (Cantell strain), TLR7 agonist(imiquimod), or TLR9 agonist (CpG-ODN) for 6h. Type I IFN gene transcription was monitored by real time qPCRfor IFNA1, A2, A5, A6, A8,A17, B1, and E1, and cytokine levels were assayed by Cytometric Bead Arrays forTNF?, IL6, IL8, IL10, IL1?, and IL12p70. pDC function as determined by these two assays showed no difference between HIV-infected and uninfected patients or between patients with early or chronic infection. Specifically, HIV did notinduce type I IFN gene expression, whereas influenza virus, Sendai virus and imiquimod did. Similarly, HIV failed to induce any cytokine release from pDCs in contrast to influenza virus, Sendai virus and imiquimod, which stimulatedrelease of TNF?, IL6, or IL8. Together these results suggest that the reaction of pDCs to HIV virus is quantitatively different from the response to agents such as virus, Sendai virus, and imiquimod. In addition, pDCs from HIV-infected persons have responses similar to pDCs from uninfected donors, suggesting, that the DC function may not be affected by HIV infection.

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