Encephalomyocarditis Virus Replication Research Articles

Assessment of Kinome-Wide Activity Remodeling upon Picornavirus Infection

Picornaviridae represent a large family of single-stranded positive RNA viruses of which different members can infect both humans and animals. These include the enteroviruses (e.g., poliovirus, coxsackievirus, and rhinoviruses) as well as the cardioviruses (e.g., encephalomyocarditis virus). Picornaviruses have evolved to interact with, use, and/or evade cellular host systems to create the optimal environment for replication and spreading. It is known that viruses modify kinase activity during infection, but a proteome-wide overview of the (de)regulation of cellular kinases during picornavirus infection is lacking. To study the kinase activity landscape during picornavirus infection, we here applied dedicated targeted mass spectrometry-based assays covering ∼40% of the human kinome. Our data show that upon infection, kinases of the MAPK pathways become activated (e.g., ERK1/2, RSK1/2, JNK1/2/3, and p38), while kinases involved in regulating the cell cycle (e.g., CDK1/2, GWL, and DYRK3) become inactivated. Additionally, we observed the activation of CHK2, an important kinase involved in the DNA damage response. Using pharmacological kinase inhibitors, we demonstrate that several of these activated kinases are essential for the replication of encephalomyocarditis virus. Altogether, the data provide a quantitative understanding of the regulation of kinome activity induced by picornavirus infection, providing a resource important for developing novel antiviral therapeutic interventions.

Histone H1.2 Inhibited EMCV Replication through Enhancing MDA5-Mediated IFN-β Signaling Pathway.

Histone H1.2 is a member of the linker histone family, which plays extensive and crucial roles not only in the regulation of chromatin dynamics, cell cycle, and cell apoptosis, but also in viral diseases and innate immunity response. Recently, it was discovered that H1.2 regulates interferon-β and inhibits influenza virus replication, whereas its role in other viral infections is poorly reported. Here, we first found the up-regulation of H1.2 during Encephalomyocarditis virus (EMCV) infection, implying that H1.2 was involved in EMCV infection. Overexpression of H1.2 inhibited EMCV proliferation, whereas knockdown of H1.2 showed a significant promotion of virus infection in HEK293T cells. Moreover, we demonstrated that overexpression of H1.2 remarkably enhanced the production of EMCV-induced type I interferon, which may be the crucial factor for H1.2 proliferation-inhibitory effects. We further found that H1.2 up-regulated the expression of the proteins of the MDA5 signaling pathway and interacted with MDA5 and IRF3 in EMCV infection. Further, we demonstrated that H1.2 facilitated EMCV-induced phosphorylation and nuclear translocation of IRF3. Briefly, our research uncovers the mechanism of H1.2 negatively regulating EMCV replication and provides new insight into antiviral targets for EMCV.

TRIM7 inhibits encephalomyocarditis virus replication by activating interferon-β signaling pathway

Tripartite motif-containing protein 7 (TRIM7), the member of tripartite motif (TRIM) family, plays an important role in innate immune responses against viral infection. Among them, the function of TRIM7 in Encephalomyocarditis virus (EMCV) infection has not been reported. Here, we found that TRIM7 inhibited the replication of EMCV through the type I interferon (IFN) signaling pathway. Interestingly, TRIM7 was down-regulated after EMCV infection in HEK293T cells. Further, overexpression of TRIM7 suppressed the replication of EMCV in HEK293T cells and enhanced the activity of IFN-β promoter. On the other hand, knockdown of the endogenous TRIM7 promoted EMCV infection and impaired the activity of IFN-β promoter. TRIM7 could regulate retinoic acid-inducible gene I (RIG-I)/ melanoma differentiation-associated gene 5 (MDA5)/ mitochondrial antiviral-signaling protein (MAVS) mediated IFN-β signaling pathway. Moreover, TRIM7 interacted with MAVS and they were co-located in HEK293T cells. We demonstrate that TRIM7 plays a positive role in IFN-β signaling pathway during EMCV infection and suppresses EMCV replication. Taken together, the presented results suggest that TRIM7 has a pivotal function in anti-EMCV infection, thereby providing a potential target for further development of anti-EMCV inhibitors.

Isoliquiritigenin inhibits virus replication and virus-mediated inflammation via NRF2 signaling

BackgroundThe transcription factor NRF2 is a master redox switch that regulates the cellular antioxidant response. However, recent advances have revealed new roles for NRF2, including the regulation of antiviral responses to various viruses, suggesting that pharmacological NRF2-activating agents may be a promising therapeutic drug for viral diseases. Isoliquiritigenin (ISL), a chalcone isolated from liquorice (Glycyrrhizae Radix) root, is reported to be a natural NRF2 agonist and has has antiviral activities against HCV (hepatitis C virus) and IAV (influenza A virus). However, the spectrum of antiviral activity and associated mechanism of ISL against other viruses are not well defined. PurposeThis study investigated the antiviral activity and underlying mechanism of ISL against vesicular stomatitis virus (VSV), influenza A virus (H1N1), encephalomyocarditis virus (EMCV), herpes simplex virus type 1 (HSV-1). MethodsWe evaluated the antiviral activity of ISL against VSV, H1N1, EMCV, and HSV-1 using flow cytometry and qRT-PCR analysis. RNA sequencing and bioinformatic analysis were performed to investigate the potential antiviral mechanism of ISL. NRF2 knockout cells were used to investigate whether NRF2 is required for the antiviral activity of ISL. The anti-apoptosis and anti-inflammatory activities of ISL were further measured by counting cell death ratio and assessing proinflammatory cytokines expression in virus-infected cells, respectively. In addition, we evaluated the antiviral effect of ISL in vivo by measuring the survival rate, body weights, histological analysis, viral load, and cytokine expression in VSV-infected mouse model. ResultsOur data demonstrated that ISL effectively suppressed VSV, H1N1, HSV-1, and EMCV replication in vitro. The antiviral activity of ISL could be partially impaired in NRF2-deficient cells. Virus-induced cell death and proinflammatory cytokines were repressed by ISL. Finally, we showed that ISL treatment protected mice against VSV infection by reducing viral titers and suppressing the expression of inflammatory cytokines in vivo. ConclusionThese findings suggest that ISL has antiviral and anti-inflammatory effects in virus infections, which are associated with its ability to activate NRF2 signaling, thus indicating that ISL has the potential to serve as an NRF2 agonist in the treatment of viral diseases.

DDX60 selectively reduces translation off viral type II internal ribosome entry sites.

Co-opting host cell protein synthesis is a hallmark of many virus infections. In response, certain host defense proteins limit mRNA translation globally, albeit at the cost of the host cell's own protein synthesis. Here, we describe an interferon-stimulated helicase, DDX60, that decreases translation from viral internal ribosome entry sites (IRESs). DDX60 acts selectively on type II IRESs of encephalomyocarditis virus (EMCV) and foot and mouth disease virus (FMDV), but not by other IRES types or by 5' cap. Correspondingly, DDX60 reduces EMCV and FMDV (type II IRES) replication, but not that of poliovirus or bovine enterovirus 1 (BEV-1; type I IRES). Furthermore, replacing the IRES of poliovirus with a type II IRES is sufficient for DDX60 to inhibit viral replication. Finally, DDX60 selectively modulates the amount of translating ribosomes on viral and in vitro transcribed type II IRES mRNAs, but not 5' capped mRNA. Our study identifies a novel facet in the repertoire of interferon-stimulated effector genes, the selective downregulation of translation from viral type II IRES elements.

Vimentin inhibits type I interferon production by disrupting the TBK1-IKKε-IRF3 axis.

Cytoskeleton proteins have been reported to be involved in the host antiviral immune responses. However, how cytoskeleton proteins regulate host antiviral immune responses is not fully understood. Here we report that the cytoskeletal protein vimentin is a negative regulator of type I interferon (IFN-I) production upon viral infection. Ectopic expression of vimentin suppresses RNA- and DNA viruses-induced IFN-I production, whereas knockout of vimentin expression enhances IFN-I production. Viral infection increases vimentin expression and ultimately inhibits IFN-I production. Mechanistically, upregulated vimentin interacts with TBK1 and IKKε to disrupt the interactions of TBK1-IRF3 and IKKε-IRF3, resulting in inhibition of IRF3 phosphorylation and nuclear translocation. Furthermore, we generate vimentin knockout mice to confirm that deficiency of vimentin gene in mice suppressed encephalomyocarditis virus replication invivo. Our findings demonstrates that vimentin plays an important role in regulating IFN-I production, revealing its antiviral function of the cytoskeletal protein vimentin.

Heat Shock Protein 60 Is Involved in Viral Replication Complex Formation and Facilitates Foot and Mouth Virus Replication by Stabilizing Viral Nonstructural Proteins 3A and 2C.

ABSTRACTThe maintenance of viral protein homeostasis depends on the machinery of the infected host cells, giving us an insight into the interplay between host and virus. Accumulating evidence suggests that heat shock protein 60 (HSP60), as one molecular chaperone, is involved in regulating virus infection. However, the role of HSP60 during foot-and-mouth disease virus (FMDV) replication and its specific mechanisms have not been reported. We demonstrate that HSP60 modulates the FMDV life cycle. HSP60 plays a role at the postentry stage of the viral life cycle, including RNA replication and mRNA translation; however, HSP60 does not affect viral replication of Seneca Valley virus (SVA) or encephalomyocarditis virus (EMCV). We found that HSP60 is involved in FMDV replication complex (RC) formation. Furthermore, our results indicate that HSP60 interacts with FMDV nonstructural proteins 3A and 2C, key elements of the viral replication complex. We also show that HSP60 regulates the stability of 3A and 2C via caspase-dependent and autophagy-lysosome-dependent degradation, thereby promoting FMDV RNA synthesis and mRNA translation mediated by the RC. Additionally, we determined that the apical domain of HSP60 is responsible for interacting with 3A and 2C. The N terminus of 3A and ATPase domain of 2C are involved in binding to HSP60. Importantly, HSP60 depletion potently reduced FMDV pathogenicity in infected mice. Altogether, this study demonstrates a specific role of HSP60 in promoting FMDV replication. Furthermore, targeting host HSP60 will help us design the FMDV-specific antiviral drugs.

DDX56 antagonizes IFN-β production to enhance EMCV replication by inhibiting IRF3 nuclear translocation

DEAD (Asp-Glu-Ala-Asp)-box RNA helicases (DDX) play important roles in viral infection, either as cytosolic viral nucleic acids sensors or as essential host factors for viral replication. In this study, we identified DDX56 as a positive regulator for encephalomyocarditis virus (EMCV) replication. EMCV infection promotes DDX56 expression via its viral proteins, VP3 and 3C. We showed that DDX56 overexpression promotes EMCV replication whereas its loss dampened EMCV replication. Consequently, knockdown of DDX56 increases type I interferon (IFN) expression during EMCV infection. We also showed that DDX56 interrupts IFN regulatory factor 3 (IRF3) phosphorylation and its nucleus translocation by directly targeting KPNA3 and KPNA4 in an EMCV-triggered MDA5 signaling activation cascade leading to the blockade of IFN-β production. Overall, we showed that DDX56 is a novel negative regulator of EMCV-mediated IFN-β responses and that DDX56 plays a critical role in EMCV replication. These findings reveal a novel strategy for EMCV to utilize a host factor to evade the host innate immune response and provide us new insight into the function of DDX56.

HSP27 Protein Dampens Encephalomyocarditis Virus Replication by Stabilizing Melanoma Differentiation-Associated Gene 5.

Heat shock proteins (HSPs) are a protein family that respond to physiological stress, such as heat, starvation, and infection. As cellular protein chaperones, they play an important role in protein folding, assembly, and degradation. Though it is well known that HSP27 is involved in a range of viral infections, its role during an encephalomyocarditis virus (EMCV) infection is not known. Here, we report that EMCV degrades HSP27 and that EMCV proteins 2Cpro and 3Apro are primarily responsible for its degradation. Consequently, loss of cellular HSP27 augmented EMCV proliferation, an effect that could be reversed upon HSP27 overexpression. Importantly, we found that HSP27 positively regulated EMCV-triggered type I interferon (IFN) production. Moreover, overexpression of 2Cpro and 3Apro significantly blocked type I IFN production. We also found for the first time that HSP27, as a molecular chaperone, can specifically interact with MDA5 and stabilize the expression of MDA5. Collectively, this study shows that HSP27 dampens EMCV infectivity by positively regulating EMCV-triggered retinoic acid-inducible gene (RIG)-I-like receptor (RLR)/melanoma differentiation-associated gene 5 (MDA5) signal pathway, while EMCV proteins 2Cpro and 3Apro interact with HSP27 and degrade HSP27 protein expression to allow EMCV proliferation. Our findings provide further mechanistic evidence for EMCV partaking in immune escape mechanisms, and that 2Cpro and 3Apro could serve as potential antiviral targets.

Host protein, HSP90β, antagonizes IFN-β signaling pathway and facilitates the proliferation of encephalomyocarditis virus in vitro

Encephalomyocarditis virus (EMCV) is a small, non-enveloped, single stranded RNA virus which infects a wide variety of mammalian species, and has zoonotic importance. Many host proteins are known to regulate EMCV proliferation by interacting with its structural or nonstructural proteins, but the regulatory role and mechanism of heat shock protein 90β (HSP90β), in EMCV infection has not been reported yet. Here, we report that overexpression of HSP90β significantly promotes the growth and proliferation of EMCV in vitro. On the contrary, down-regulation of HSP90β by RNAi or geldanamycin inhibits EMCV replication. HSP90β suppresses IFN-β responses in the RLRs pathway by targeting the expression of the key adaptor molecules MAVS, TBK1, and IRF3, but not MDA5. This study demonstrates the firsthand information that HSP90β plays a positive role in viral proliferation by inhibiting EMCV induced IFN-β production. Collectively, the results reveal new insights into HSP90β-assisted progression of EMCV infection.

Caveolin-1 is involved in encephalomyocarditis virus replication in BHK-21 cells

BackgroundEncephalomyocarditis virus, member of Cardiovirus genus within Picornaviridae family, is an important pathogen that infects different domestic and wild animals. However, the molecular mechanism of its entry remains unclear. In this study, we investigated the mechanism of EMCV infectivity in relation to endocytic pathway using BHK-21 cells.MethodsThe function of numerous cellular key factors implicated in the various endocytic mechanisms were systematically explored using chemical inhibitors. Furthermore, RNA interference (RNAi) as well as the overexpression of dominant protein combined to virus infectivity assays, and confocal microscopy was used to examine EMCV infection in details.ResultsThe results indicated that the EMCV entry into BHK-21 cells depends on caveolin, dynamin, and actin but not clathrin nor macropinocytosis pathways. The effects of overexpression and knockdown of caveolin-1, one components of the caveolae, was examined on EMCV infection. The results showed that EMCV infection was positive correlation with caveolin-1 expression. Confocal microscopy analysis and internalization assay showed that caveolin-1 is required at the early stage of EMCV infection.ConclusionsCaveolin-1, dynamin, and actin-dependent endocytosis pathways are necessary for EMCV infection in vitro.

Inhibition of oxidative metabolism by nitric oxide restricts EMCV replication selectively in pancreatic beta-cells

Environmental factors, such as viral infection, are proposed to play a role in the initiation of autoimmune diabetes. In response to encephalomyocarditis virus (EMCV) infection, resident islet macrophages release the pro-inflammatory cytokine IL-1β, to levels that are sufficient to stimulate inducible nitric oxide synthase (iNOS) expression and production of micromolar levels of the free radical nitric oxide in neighboring β-cells. We have recently shown that nitric oxide inhibits EMCV replication and EMCV-mediated β-cell lysis and that this protection is associated with an inhibition of mitochondrial oxidative metabolism. Here we show that the protective actions of nitric oxide against EMCV infection are selective for β-cells and associated with the metabolic coupling of glycolysis and mitochondrial oxidation that is necessary for insulin secretion. Inhibitors of mitochondrial respiration attenuate EMCV replication in β-cells, and this inhibition is associated with a decrease in ATP levels. In mouse embryonic fibroblasts (MEFs), inhibition of mitochondrial metabolism does not modify EMCV replication or decrease ATP levels. Like most cell types, MEFs have the capacity to uncouple the glycolytic utilization of glucose from mitochondrial respiration, allowing for the maintenance of ATP levels under conditions of impaired mitochondrial respiration. It is only when MEFs are forced to use mitochondrial oxidative metabolism for ATP generation that mitochondrial inhibitors attenuate viral replication. In a β-cell selective manner, these findings indicate that nitric oxide targets the same metabolic pathways necessary for glucose stimulated insulin secretion for protection from viral lysis.

Inhibition of mitochondrial oxidative metabolism attenuates EMCV replication and protects β-cells from virally mediated lysis

Viral infection is one environmental factor that may contribute to the initiation of pancreatic β-cell destruction during the development of autoimmune diabetes. Picornaviruses, such as encephalomyocarditis virus (EMCV), induce a pro-inflammatory response in islets leading to local production of cytokines, such as IL-1, by resident islet leukocytes. Furthermore, IL-1 is known to stimulate β-cell expression of iNOS and production of the free radical nitric oxide. The purpose of this study was to determine whether nitric oxide contributes to the β-cell response to viral infection. We show that nitric oxide protects β-cells against virally mediated lysis by limiting EMCV replication. This protection requires low micromolar, or iNOS-derived, levels of nitric oxide. At these concentrations nitric oxide inhibits the Krebs enzyme aconitase and complex IV of the electron transport chain. Like nitric oxide, pharmacological inhibition of mitochondrial oxidative metabolism attenuates EMCV-mediated β-cell lysis by inhibiting viral replication. These findings provide novel evidence that cytokine signaling in β-cells functions to limit viral replication and subsequent β-cell lysis by attenuating mitochondrial oxidative metabolism in a nitric oxide–dependent manner.

54-OR: Nitric Oxide Attenuates Viral Replication in Pancreatic ß-Cells through an Inhibition of Mitochondrial Oxidative Metabolism

Viral infection has been identified as an environmental factor that may play a role in initiating the destruction of pancreatic β-cells during the development of autoimmune diabetes. We have identified a pro-inflammatory response activated in pancreatic islets in response to infection with encephalomyocarditis virus (EMCV). In response to the local production of cytokines such as IL-1 by resident islet macrophages, β-cells produce nitric oxide, a free radical with known antiviral activity. Nitric oxide has been characterized both as a potent antiviral molecule and as a mediator of β-cell dysfunction and damage and so we investigated the role of nitric oxide in controlling β-cell viability in the context of EMCV infection. We find that nitric oxide, either supplied exogenously with donor compounds or produced endogenously in response to cytokine treatment, attenuates EMCV replication and protects β-cells against EMCV-mediated death. These protective actions of nitric oxide are restricted to conditions in which nitric oxide is produced at low micromolar levels (consistent with the levels of nitric oxide generated by iNOS) and are associated with the ability of nitric oxide to impair mitochondrial oxidation and decrease ATP levels in β-cells. Treatment with rotenone, an inhibitor of complex I of the electron transport chain, likewise attenuates EMCV replication in β-cells, which are reliant on oxidative metabolism for ATP generation, but not in fibroblasts, which can sustain ATP levels via glycolysis alone. These findings suggest a mechanism of protection restricted to β-cells where nitric oxide production attenuates viral replication by inhibiting oxidative metabolism and depleting cellular stores of ATP, supporting a protective role for nitric oxide in the response of β-cells to viral infection. Disclosure J. Stafford: None. J.A. Corbett: None. Funding American Heart Association (17PRE3253000); National Institutes of Health (DK052194, AI44458)

Production of Antiviral Substance from Sugarcane Bagasse by Chemical Alteration of its Native Lignin Structure through Microwave Solvolysis.

The production of bioactive agents from lignocelluloses has received limited attention because plant cell walls are essentially non-bioactive. In this study, a chemical reaction is reported, which produces a lignin-derived antiviral substance from sugarcane bagasse by microwave heating at 200 °C in aqueous glycerol containing 0.5 % H2 SO4 . The purified fraction, designated as FR200 , strongly inhibited the replication of encephalomyocarditis virus (EMCV) in L929 cells without cytotoxicity. HSQC NMR spectra demonstrated that the principal interunit linkages in the native lignin were cleaved by the reaction. Gel permeation chromatography (GPC) and pyrolysis-GCMS revealed that FR200 is composed of oligomeric lignin with a weight average molecular weight of approximately 2000. When the bagasse was reacted at lower temperatures, 140 °C and 160 °C, the native lignin substructures were partially retained and the antiviral activity significantly decreased. The results thus indicate that the antiviral activity emerged through severe alteration of the native lignin structure. Furthermore, it was revealed that the antiviral lignin inactivated the EMCV virions through direct contact, as the innate immune system of L929 was not activated by FR200 treatment, and no antiviral activity was found when L929 was pre-treated with the lignin before viral infection.

Role of pattern recognition receptors and interferon-beta in protecting bat cell lines from encephalomyocarditis virus and Japanese encephalitis virus infection

Bats are potential natural hosts of Encephalomyocarditis virus (EMCV) and Japanese encephalitis virus (JEV). Bats appear to have some unique features in their innate immune system that inhibit viral replication causing limited clinical symptoms, and thus, contributing to the virus spill over to humans. Here, kidney epithelial cell lines derived from four bat species (Pteropus dasymallus, Rousettus leschenaultii, Rhinolophus ferrumequinum, and Miniopterus fuliginosus) and two non-bat species (Homo sapiens and Mesocricetus auratus) were infected with EMCV and JEV. The replication of EMCV and JEV was lower in the bat cell lines derived from R. leschenaultii, R. ferrumequinum, and M. fuliginosus with a higher expression level of pattern recognition receptors (PRRs) (TLR3, RIG-I, and MDA5) and interferon-beta (IFN-β) than that in the non-bat cell lines and a bat cell line derived from P. dasymallus. The knockdown of TLR3, RIG-I, and MDA5 in Rhinolophus bat cell line using antisense RNA oligonucleotide led to decrease IFN-β expression and increased viral replication. These results suggest that TLR3, RIG-I, and MDA5 are important for antiviral response against EMCV and JEV in Rhinolophus bats.

Cholesterol 25-hydroxylase inhibits encephalomyocarditis virus replication through enzyme activity-dependent and independent mechanisms

Cholesterol-25-hydroxylase (CH25 H) is a reticulum-associated membrane protein induced by an important interferon-stimulating gene (ISG) and can significantly inhibit some virus replication. But the effect of CH25H on encephalomyocarditis virus (EMCV) is still not clear. In this study, we found that EMCV infection increases significantly the endogenous CH25H expression in BHK-21 and N2a cells. CH25H and cholesterol catalytic oxidation product 25-hydroxycholesterol (25HC) obviously inhibits EMCV infection by inhibiting the viral penetration. But the CH25H mutant lacking hydroxylase activity repairs the ability to inhibit the viral replication. Meanwhile, β-cyclodextrin crystalline as a cholesterol inhibitor significantly decreases the viral replication. In addition, CH25H can selectively interact and degrade the viral RNA-Dependent RNA Polymerase-3D protein by independent on the association of proteasome, lysosome and caspase manner. It provides new insights into the interplay mechanisms between CH25H and non-enveloped single-stranded positive RNA viruses.

Inhibition of encephalomyocarditis virus replication by shRNA targeting 1C and 2A genes in vitro and in vivo

Encephalomyocarditis virus (EMCV) infects many mammalian species, causing myocarditis, encephalitis and reproductive disorders. The small interference RNA (siRNA) targeting to the virus has not been understood completely. Here, two out of six interference sequences were screened to inhibit significantly EMCV replication by using recombinant plasmids expressing small hairpin RNA (shRNA) targeting to the viral 1C or 2A genes in BHK-21 cells. And two recombinant adenoviruses expressing the shRNAs were constructed and named as rAd-1C-1 and rAd-2A-3. They inhibit EMCV replication in BHK-21 cells in protein levels, as well as the virus yields by approximately 1000 times. Furthermore, they provide high protective efficacy against the challenge with virulent EMCV NJ08 strain in mice. And the EMCV loads in the live mice in rAd-1C-1 and rAd-2A-3 groups decrease by more than 90 % compared with those in the dead mice in the challenge control groups at the same times. It indicates that the adenoviruses medicated shRNA targeting to 1C and 2A genes might provide a potential strategy for combating EMCV infection.

Transmembrane Protein 39A Promotes the Replication of Encephalomyocarditis Virus via Autophagy Pathway.

Encephalomyocarditis virus (EMCV) causes encephalitis, myocarditis, neuropathy, reproductive disorders, and diabetes in animals. EMCV is known to induce cell autophagy; however, the molecular mechanisms underlying this remain unclear. Here, we show that the type III-transmembrane protein, transmembrane protein 39A (TMEM39A), plays a critical role in EMCV replication. We showed that EMCV GS01 strain infection upregulated TMEM39A expression. Importantly, EMCV induced autophagy in a range of host cells. The autophagy chemical inhibitor, 3-MA, inhibited EMCV replication and reduced TMEM39A expression. This is the first study demonstrating TMEM39A promoting the replication of EMCV via autophagy. Overall, we show that TMEM39A plays a positive regulatory role in EMCV proliferation and that TMEM39A expression is dependent on the autophagy pathway.

Exploitation of nuclear protein SFPQ by the encephalomyocarditis virus to facilitate its replication

The encephalomyocarditis virus (EMCV) is a single-stranded RNA virus that induces sudden death, diabetes, myocarditis and nervous disorders in non-human primates. The rapid development of xenografts such as heart transplantation from pig to human raises the issue of EMCV safety in human cells. SFPQ, a proline and glutamine rich splicing factor that participates in diverse molecular functions including paraspeckle formation, microRNA synthesis and transcription regulation, is known to regulate host innate immune response to viruses. However, the role of SFPQ in EMCV infection remains unclear. Here we reported that the SFPQ was essential for EMCV replication. Depletion of SFPQ impaired EMCV production, while forced expression of SFPQ promoted viral replication. Mechanistically, loss of SFPQ affected the transcription profile of host mitochondria pathway related genes. In addition, cellular SFPQ was exploited by EMCV and accumulated in cytoplasm and it interacted with eukaryotic initiation factors and ribosomal proteins to facilitate internal ribosome entry site (IRES)-dependent translation of EMCV protein. Altogether, our work discovered host SFPQ as a new target to inhibit EMCV replication and infection.