scholarly journals Identification of an LGP2-associated MDA5 agonist in picornavirus-infected cells

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Safia Deddouche ◽  
Delphine Goubau ◽  
Jan Rehwinkel ◽  
Probir Chakravarty ◽  
Sharmin Begum ◽  
...  
Keyword(s):  
Antisense Rna ◽  
Rna Synthesis ◽  
In Vitro Transcription ◽  
Encephalomyocarditis Virus ◽  
Type I Interferons ◽  
Type I ◽  
Specific Sequence ◽  
Infected Cells ◽  
Rna Complexes

The RIG-I-like receptors RIG-I, LGP2, and MDA5 initiate an antiviral response that includes production of type I interferons (IFNs). The nature of the RNAs that trigger MDA5 activation in infected cells remains unclear. Here, we purify and characterise LGP2/RNA complexes from cells infected with encephalomyocarditis virus (EMCV), a picornavirus detected by MDA5 and LGP2 but not RIG-I. We show that those complexes contain RNA that is highly enriched for MDA5-stimulatory activity and for a specific sequence corresponding to the L region of the EMCV antisense RNA. Synthesis of this sequence by in vitro transcription is sufficient to generate an MDA5 stimulatory RNA. Conversely, genomic deletion of the L region in EMCV generates viruses that are less potent at stimulating MDA5-dependent IFN production. Thus, the L region antisense RNA of EMCV is a key determinant of innate immunity to the virus and represents an RNA that activates MDA5 in virally-infected cells.

scholarly journals HIV-Infected Macrophages Are Infected and Killed by the Interferon-Sensitive Rhabdovirus MG1

2021 ◽  
Vol 95 (9) ◽  
Author(s):  
Teslin S. Sandstrom ◽  
Nischal Ranganath ◽  
Stephanie C. Burke Schinkel ◽  
Syim Salahuddin ◽  
Oussama Meziane ◽  
...  
Keyword(s):  
Cancer Cells ◽  
Oncolytic Viruses ◽  
Type I Interferons ◽  
Viral Reservoir ◽  
Type I ◽  
Antiviral Signaling ◽  
Infected Cells ◽  
Hiv 1

ABSTRACT The use of unique cell surface markers to target and eradicate HIV-infected cells has been a longstanding objective of HIV-1 cure research. This approach, however, overlooks the possibility that intracellular changes present within HIV-infected cells may serve as valuable therapeutic targets. For example, the identification of dysregulated antiviral signaling in cancer has led to the characterization of oncolytic viruses capable of preferentially killing cancer cells. Since impairment of cellular antiviral machinery has been proposed as a mechanism by which HIV-1 evades immune clearance, we hypothesized that HIV-infected macrophages (an important viral reservoir in vivo) would be preferentially killed by the interferon-sensitive oncolytic Maraba virus MG1. We first showed that HIV-infected monocyte-derived macrophages (MDM) were more susceptible to MG1 infection and killing than HIV-uninfected cells. As MG1 is highly sensitive to type I interferons (IFN-I), we then investigated whether we could identify IFN-I signaling differences between HIV-infected and uninfected MDM and found evidence of impaired IFN-α responsiveness within HIV-infected cells. Finally, to assess whether MG1 could target a relevant, primary cell reservoir of HIV-1, we investigated its effects in alveolar macrophages (AM) obtained from effectively treated individuals living with HIV-1. As observed with in vitro-infected MDM, we found that HIV-infected AM were preferentially eliminated by MG1. In summary, the oncolytic rhabdovirus MG1 appears to preferentially target and kill HIV-infected cells via impairment of antiviral signaling pathways and may therefore provide a novel approach to an HIV-1 cure. IMPORTANCE Human immunodeficiency virus type 1 (HIV-1) remains a treatable, but incurable, viral infection. The establishment of viral reservoirs containing latently infected cells remains the main obstacle in the search for a cure. Cure research has also focused on only one cellular target of HIV-1 (the CD4+ T cell) while largely overlooking others (such as macrophages) that contribute to HIV-1 persistence. In this study, we address these challenges by describing a potential strategy for the eradication of HIV-infected macrophages. Specifically, we show that an engineered rhabdovirus—initially developed as a cancer therapy—is capable of preferential infection and killing of HIV-infected macrophages, possibly via the same altered antiviral signaling seen in cancer cells. As this rhabdovirus is currently being explored in phase I/II clinical trials, there is potential for this approach to be readily adapted for use within the HIV-1 cure field.

scholarly journals NF-κB-Mediated Inhibition of Apoptosis Is Required for Encephalomyocarditis Virus Virulence: a Mechanism of Resistance in p50 Knockout Mice

1998 ◽  
Vol 72 (7) ◽  
pp. 5654-5660 ◽  
Author(s):  
Edward M. Schwarz ◽  
Cornel Badorff ◽  
Timothy S. Hiura ◽  
Rainer Wessely ◽  
Annette Badorff ◽  
...  
Keyword(s):  
Cell Lines ◽  
Knockout Mice ◽  
Defense Mechanism ◽  
Encephalomyocarditis Virus ◽  
Type I ◽  
Double Knockout ◽  
Physiological Importance ◽  
Infected Cells

ABSTRACT Apoptosis is a central host defense mechanism to eliminate virus-infected cells. Activation of NF-κB suppresses apoptosis following some types of stimulation in vitro. To test the physiological importance of this pathway in vivo, we studied murine encephalomyocarditis virus (EMCV) infection in mice and cell lines defective in NF-κB1 (p50) signaling. As previously reported, we find that all p50 knockout (p50 −/−) mice survive an EMCV infection that readily kills normal mice. By introducing the p50 mutation into interferon (IFN) type I receptor knockout (IFNRI −/−) mice, we find that this resistance is not mediated by IFN-β as previously thought. While no IFNRI −/− mice survive, the double-knockout mice survive 60% of the time. The survival is tightly linked to the animals’ ability to clear the virus from the heart in vivo. Using murine embryonic fibroblasts (MEF) derived from wild-type, p50 −/−, and p65 −/− embryos, we found that NF-κB is not required for the replication cycle of EMCV. However, during these experiments we observed that p50 −/− and p65 −/− MEF infected with EMCV undergo enhanced, premature cytotoxicity. Upon examination of this cell death, we found that EMCV infection induced both plasma membrane and nuclear changes typical of apoptosis in all cell lines. These apoptotic processes occurred in an accelerated and pronounced way in the NF-κB-defective cells, as soon as 6 h after infection, when virus is beginning to be released. Previously, only the RelA (p65) subunit of NF-κB has been shown to play a role in suppressing apoptosis. In our studies, we find that p50 is equally important in suppressing apoptosis during EMCV infection. Additionally, we show that suppression of apoptosis by NF-κB1 is required for EMCV virulence in vivo. The attenuation in p50 −/− mice can be explained by rapid apoptosis of infected cells which allows host phagocytes to clear infected cells before the viral burst leading to a reduction of the viral burden and survival of the mice.

scholarly journals Type I interferon-dependent CCL4 is induced by a cGAS/STING pathway that bypasses viral inhibition and protects infected tissue, independent of viral burden

2019 ◽  
Author(s):  
Nikhil J. Parekh ◽  
Tracy E. Krouse ◽  
Irene E. Reider ◽  
Ryan P. Hobbs ◽  
Brian M. Ward ◽  
...  
Keyword(s):  
Virus Replication ◽  
Infected Tissue ◽  
Type I Interferons ◽  
Type I ◽  
Wild Type ◽  
Inflammatory Monocytes ◽  
Viral Burden ◽  
Infected Cells

AbstractType I interferons (T1-IFN) are critical in the innate immune response, acting upon infected and uninfected cells to initiate an antiviral state by expressing genes that inhibit multiple stages of the lifecycle of many viruses. T1-IFN triggers the production of Interferon-Stimulated Genes (ISGs), activating an antiviral program that reduces virus replication. The importance of the T1-IFN response is highlighted by the evolution of viral evasion strategies to inhibit the production or action of T1-IFN in virus-infected cells. T1-IFN is produced via activation of pathogen sensors within infected cells, a process that is targeted by virus-encoded immunomodulatory molecules. This is probably best exemplified by the prototypic poxvirus, Vaccinia virus (VACV), which uses at least 6 different mechanisms to completely block the production of T1-IFN within infected cells in vitro. Yet, mice lacking aspects of T1-IFN signaling are often more susceptible to infection with many viruses, including VACV, than wild-type mice. How can these opposing findings be rationalized? The cytosolic DNA sensor cGAS has been implicated in immunity to VACV, but has yet to be linked to the production of T1-IFN in response to VACV infection. Indeed, there are two VACV-encoded proteins that effectively prevent cGAS-mediated activation of T1-IFN. We find that the majority of VACV-infected cells in vivo do not produce T1-IFN, but that a small subset of VACV-infected cells in vivo utilize cGAS to sense VACV and produce T1-IFN to protect infected mice. The protective effect of T1-IFN is not mediated via ISG-mediated control of virus replication. Rather, T1-IFN drives expression of CCL4, which recruits inflammatory monocytes that constrain the VACV lesion in a virus replication-independent manner by limiting spread within the tissue. Our findings have broad implications in our understanding of pathogen detection and viral evasion in vivo, and highlight a novel immune strategy to protect infected tissue.SummaryThe recognition of virus infection leads to a quick and robust antiviral response mediated by type I interferons (T1-IFN). Nearly all viruses have acquired genes that block the induction or action of T1-IFN in order to attain a replicative advantage. Some viruses thwart the T1-IFN response so thoroughly, that cells infected in vitro do not produce any T1-IFN. And yet, animal models with defects in T1-IFN signaling are more sensitive to infection with these viruses than their wild-type counterparts. In this study, we find evidence to explain these otherwise contradicting findings. We show that a small population of infected cells in vivo are able to utilize a pathogen-sensing pathway that is completely blocked in vitro. T1-IFN produced by these specialized cells protects mice by recruiting inflammatory monocytes that restrict the spread of virus within infected tissue, independent of viral burden. Our findings have a direct impact on our understanding of how viruses are detected in infected tissue, and present a novel strategy of the immune system to limit pathology at peripheral sites of infection.

Type I Interferons promote maintenance and function of follicular T helper cells in vitro

2019 ◽  
Author(s):  
S Ehrlich ◽  
K Wild ◽  
M Smits ◽  
K Zoldan ◽  
M Hofmann ◽  
...  
Keyword(s):  
T Helper Cells ◽  
Type I Interferons ◽  
Type I ◽  
T Helper ◽  
Helper Cells ◽  
Follicular T Helper Cells ◽  
And Function

Studies of two temperature-sensitive mutants of Mengo virus

1979 ◽  
Vol 57 (6) ◽  
pp. 902-913 ◽  
Author(s):  
Patrick W. K. Lee ◽  
John S. Colter
Keyword(s):  
Rna Synthesis ◽  
Viral Rna ◽  
Temperature Sensitive ◽  
Supporting Evidence ◽  
Structural Polypeptide ◽  
Infected Cells ◽  
Mengo Virus ◽  
In Vitro Stability

Studies of the synthesis of viral ribonucleates and polypeptides in cells infected with two RNA−ts mutants of Mengo virus (ts 135 and ts 520) have shown that when ts 135 infected cells are shifted from the permissive (33 °C) to the nonpermissive (39 °C) temperature: (i) the synthesis of all three species of viral RNA (single stranded, replicative form, and replicative intermediate) is inhibited to about the same extent, and (ii) the posttranslational cleavage of structural polypeptide precursors A and B is partially blocked. Investigations of the in vivo and in vitro stability of the viral RNA replicase suggest that the RNA− phentotype reflects a temperature-sensitive defect in the enzyme. The second defect does not appear to result from the inhibition of viral RNA synthesis at 39 °C, since normal cleavage of polypeptides A and B occurs in wt Mengo-infected cells in which viral RNA synthesis is blocked by cordycepin, and at the nonpermissive temperature in ts 520 infected cells. Considered in toto, the evidence suggests that ts 135 is a double mutant.Subviral (53 S) particles have been shown to accumulate in ts 520 (but not ts 135) infected cells when cultures are shifted from 33 to 39 °C. This observation provides supporting evidence for the proposal that this recently discovered particle is an intermediate in the assembly pathway of Mengo virions.

scholarly journals Transcriptional role of p53 in interferon-mediated antiviral immunity

2008 ◽  
Vol 205 (8) ◽  
pp. 1929-1938 ◽  
Author(s):  
César Muñoz-Fontela ◽  
Salvador Macip ◽  
Luis Martínez-Sobrido ◽  
Lauren Brown ◽  
Joseph Ashour ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Viral Replication ◽  
Viral Infections ◽  
Suppressor Gene ◽  
Central Component ◽  
Type I ◽  
Infected Cells

Tumor suppressor p53 is activated by several stimuli, including DNA damage and oncogenic stress. Previous studies (Takaoka, A., S. Hayakawa, H. Yanai, D. Stoiber, H. Negishi, H. Kikuchi, S. Sasaki, K. Imai, T. Shibue, K. Honda, and T. Taniguchi. 2003. Nature. 424:516–523) have shown that p53 is also induced in response to viral infections as a downstream transcriptional target of type I interferon (IFN) signaling. Moreover, many viruses, including SV40, human papillomavirus, Kaposi's sarcoma herpesvirus, adenoviruses, and even RNA viruses such as polioviruses, have evolved mechanisms designated to abrogate p53 responses. We describe a novel p53 function in the activation of the IFN pathway. We observed that infected mouse and human cells with functional p53 exhibited markedly decreased viral replication early after infection. This early inhibition of viral replication was mediated both in vitro and in vivo by a p53-dependent enhancement of IFN signaling, specifically the induction of genes containing IFN-stimulated response elements. Of note, p53 also contributed to an increase in IFN release from infected cells. We established that this p53-dependent enhancement of IFN signaling is dependent to a great extent on the ability of p53 to activate the transcription of IFN regulatory factor 9, a central component of the IFN-stimulated gene factor 3 complex. Our results demonstrate that p53 contributes to innate immunity by enhancing IFN-dependent antiviral activity independent of its functions as a proapoptotic and tumor suppressor gene.

scholarly journals A host type I interferon response is induced by cytosolic sensing of the bacterial second messenger cyclic-di-GMP

2009 ◽  
Vol 206 (9) ◽  
pp. 1899-1911 ◽  
Author(s):  
Sarah M. McWhirter ◽  
Roman Barbalat ◽  
Kathryn M. Monroe ◽  
Mary F. Fontana ◽  
Mamoru Hyodo ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Map Kinases ◽  
Second Messenger ◽  
Innate Immune ◽  
Guanosine Monophosphate ◽  
Host Cells ◽  
Type I Interferons ◽  
Interferon Response ◽  
Type I

The innate immune system responds to unique molecular signatures that are widely conserved among microbes but that are not normally present in host cells. Compounds that stimulate innate immune pathways may be valuable in the design of novel adjuvants, vaccines, and other immunotherapeutics. The cyclic dinucleotide cyclic-di–guanosine monophosphate (c-di-GMP) is a recently appreciated second messenger that plays critical regulatory roles in many species of bacteria but is not produced by eukaryotic cells. In vivo and in vitro studies have previously suggested that c-di-GMP is a potent immunostimulatory compound recognized by mouse and human cells. We provide evidence that c-di-GMP is sensed in the cytosol of mammalian cells via a novel immunosurveillance pathway. The potency of cytosolic signaling induced by c-di-GMP is comparable to that induced by cytosolic delivery of DNA, and both nucleic acids induce a similar transcriptional profile, including triggering of type I interferons and coregulated genes via induction of TBK1, IRF3, nuclear factor κB, and MAP kinases. However, the cytosolic pathway that senses c-di-GMP appears to be distinct from all known nucleic acid–sensing pathways. Our results suggest a novel mechanism by which host cells can induce an inflammatory response to a widely produced bacterial ligand.

scholarly journals Cannabinoid Reduces Inflammatory Cytokines, Tumor Necrosis Factor-α, and Type I Interferons in Dermatomyositis In Vitro

2017 ◽  
Vol 137 (11) ◽  
pp. 2445-2447 ◽  
Author(s):  
Elizabeth S. Robinson ◽  
Paul Alves ◽  
Muhammad M. Bashir ◽  
Majid Zeidi ◽  
Rui Feng ◽  
...  
Keyword(s):  
Tumor Necrosis Factor ◽  
Inflammatory Cytokines ◽  
Tumor Necrosis ◽  
Tumor Necrosis Factor Α ◽  
Type I Interferons ◽  
Type I ◽  
Factor Α ◽  
Necrosis Factor

scholarly journals Thioredoxin 2 Negatively Regulates Innate Immunity to RNA Viruses by Disrupting the Assembly of the Virus-Induced Signaling Adaptor Complex

2020 ◽  
Vol 94 (7) ◽  
Author(s):  
Dan Li ◽  
Wenping Yang ◽  
Yi Ru ◽  
Jingjing Ren ◽  
Xiangtao Liu ◽  
...  
Keyword(s):  
Complex Formation ◽  
Rna Viruses ◽  
Critical Role ◽  
Type I Interferons ◽  
Type I ◽  
Host Proteins ◽  
Innate Antiviral Response ◽  
Thioredoxin 2

ABSTRACT The virus-induced signaling adaptor (VISA) complex plays a critical role in the innate immune response to RNA viruses. However, the mechanism of VISA complex formation remains unclear. Here, we demonstrate that thioredoxin 2 (TRX2) interacts with VISA at mitochondria both in vivo and in vitro. Knockdown and knockout of TRX2 enhanced the formation of the VISA-associated complex, as well as virus-triggered activation of interferon regulatory factor 3 (IRF3) and transcription of the interferon beta 1 (IFNB1) gene. TRX2 inhibits the formation of VISA aggregates by repressing reactive oxygen species (ROS) production, thereby disrupting the assembly of the VISA complex. Furthermore, our data suggest that the C93 residue of TRX2 is essential for inhibition of VISA aggregation, whereas the C283 residue of VISA is required for VISA aggregation. Collectively, these findings uncover a novel mechanism of TRX2 that negatively regulates VISA complex formation. IMPORTANCE The VISA-associated complex plays pivotal roles in inducing type I interferons (IFNs) and eliciting the innate antiviral response. Many host proteins are identified as VISA-associated-complex proteins, but how VISA complex formation is regulated by host proteins remains enigmatic. We identified the TRX2 protein as an important regulator of VISA complex formation. Knockout of TRX2 increases virus- or poly(I·C)-triggered induction of type I IFNs at the VISA level. Mechanistically, TRX2 inhibits the production of ROS at its C93 site, which impairs VISA aggregates at its C283 site, and subsequently impedes the assembly of the VISA complex. Our findings suggest that TRX2 plays an important role in the regulation of VISA complex assembly.

scholarly journals Enhancing innate antiviral immune responses in rainbow trout by double stranded RNA delivered with cationic phytoglycogen nanoparticles

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Tamiru N. Alkie ◽  
Jondavid de Jong ◽  
Kristof Jenik ◽  
Karl M. Klinger ◽  
Stephanie J. DeWitte-Orr
Keyword(s):  
Rainbow Trout ◽  
Immune Responses ◽  
Cell Line ◽  
Culture Conditions ◽  
Type I Interferons ◽  
Poly I:C ◽  
Synthetic Analogue ◽  
Type I ◽  
Viral Dsrna

Abstract Innate immunity is induced when pathogen-associated molecular patterns (PAMPs) bind host pattern recognition receptors (PRRs). Polyinosinic:polycytidylic acid [poly(I:C)] is a synthetic analogue of viral dsRNA that acts as a PAMP, inducing type I interferons (IFNs) in vertebrates. In the present study, the immunostimulatory effects of high molecular weight (HMW) poly(I:C) in rainbow trout cells were measured when bound to a cationic phytoglycogen nanoparticle (Nano-HMW). The physical characteristics of the nanoparticle itself, when bound to different lengths of dsRNA and when cell associated was evaluated. Optimal concentration and timing for innate immune stimulation was measured using the RTG-P1 reporter cell line. The immunostimulatory effects of HMW poly (I:C) was compared to Nano-HMW in vitro using the RTgutGC cell line cultured in a conventional monolayer or a transwell culture system. The ability of an activated intestinal epithelium to transmit an antiviral signal to macrophages was evaluated using a co-culture of RTgutGC cells and RTSll (a monocyte/macrophage cell). In all culture conditions, Nano-HMW was a more effective inducer of IFN-related antiviral immune responses compared to HMW poly (I:C) alone. This study introduces the use of cationic phytoglycogen nanoparticles as a novel delivery system for immunomodulatory molecules to enhance immune responses in aquatic vertebrates.

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