Classical swine fever virus Ernsglycoprotein antagonizes induction of interferon-β by double-stranded RNA

Classical swine fever virus (CSFV) is capable of counteracting innate cellular antiviral responses by inhibiting type I interferon (IFN)-α/β induction. A function associated with CSFV Npro, with respect to the inhibition of IFN-β production, has been clearly elucidated. In this study, we explored the role of CSFV Ernsin IFN-β induction by exogenous double-stranded (ds) RNA. Synthetic dsRNA (poly (IC)) was used as an exogenous stimulus to trigger IFN-β induction. CSFV Ernsinhibited IFN-β promoter-driven luciferase activity induced by poly (IC) in different cell lines, and the inhibitory effect was dose-dependent. Moreover, Ernsreduced IFN-β mRNA synthesis and blocked IFN-α/β production induced by poly (IC), suggesting that this inhibition occurs at the transcriptional level. Furthermore, Ernscounteracted poly (IC)-mediated IFN-β induction independent of its ribonuclease activity. In conclusion, CSFV Ernsantagonizes extracellular dsRNA-mediated IFN-β expression. These findings contribute to our understanding of the pathogenesis of CSFV.

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Classical swine fever virus NS5B protein suppresses the inhibitory effect of NS5A on viral translation by binding to NS5A

Journal of General Virology ◽

10.1099/vir.0.039495-0 ◽

2012 ◽

Vol 93 (5) ◽

pp. 939-950 ◽

Cited By ~ 13

Author(s):

Chun Sheng ◽

Jing Wang ◽

Jing Xiao ◽

Jun Xiao ◽

Yan Chen ◽

...

Keyword(s):

Amino Acids ◽

Classical Swine Fever Virus ◽

Classical Swine Fever ◽

Inhibitory Effect ◽

Fever Virus ◽

Viral Translation ◽

Ns5a Protein ◽

Gdd Motif ◽

Ns5b Protein

In order to investigate molecular mechanisms of internal ribosome entry site (IRES)-mediated translation in classical swine fever virus (CSFV), an important pathogen of pigs, the expression level of NS3 was evaluated in the context of genomic RNAs and reporter RNA fragments. All data showed that the NS5A protein has an inhibitory effect on IRES-mediated translation and that NS5B proteins suppress the inhibitory effect of NS5A on viral translation, but CSFV NS5B GDD mutants do not. Furthermore, glutathione S-transferase pull-down assay and immunoprecipitation analysis, associated with deletion and alanine-scanning mutations, were performed. Results showed that NS5B interacts with NS5A and that the region aa 390–414, located in the C-terminal half of NS5A, is important for binding of NS5B to NS5A. Furthermore, amino acids K399, T401, E406 and L413 in the region were found to be essential for NS5A–NS5B interaction, virus rescue and infection. The above-mentioned region and four amino acids were observed to overlap with the site responsible for inhibition of IRES-mediated translation by the NS5A protein. We also found that aa 63–72, aa 637–653 and the GDD motif of NS5B were necessary for the interaction between NS5A and NS5B. These findings suggest that the repression activity of the NS5B protein toward the role of NS5A in translation might be achieved by NS5A–NS5B interaction, for which aa 390–414 of NS5A and aa 63–72, aa 637–653 and the GDD motif of NS5B are indispensable. This is important for understanding the role of NS5A–NS5B interaction in the virus life cycle.

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Interferon-Inducible Oligoadenylate Synthetase-Like Protein Acts as an Antiviral Effector against Classical Swine Fever Virus via the MDA5-Mediated Type I Interferon-Signaling Pathway

Journal of Virology ◽

10.1128/jvi.01514-16 ◽

2017 ◽

Vol 91 (11) ◽

Cited By ~ 16

Author(s):

Lian-Feng Li ◽

Jiahui Yu ◽

Yuexiu Zhang ◽

Qian Yang ◽

Yongfeng Li ◽

...

Keyword(s):

Signaling Pathway ◽

Classical Swine Fever Virus ◽

Classical Swine Fever ◽

Fever Virus ◽

Transcriptional Level ◽

Type I ◽

Dependent Manner ◽

Type I Ifn ◽

Small Interfering Rnas ◽

Oligoadenylate Synthetase

ABSTRACT Classical swine fever virus (CSFV) is the causative agent of classical swine fever (CSF), which poses a serious threat to the global pig industry. Interferons (IFNs) and IFN-stimulated genes (ISGs) play a key role in host antiviral defense. We have previously screened the porcine 2′-5′-oligoadenylate synthetase-like protein (pOASL) as a potential anti-CSFV ISG using a reporter CSFV. This study aimed to clarify the underlying antiviral mechanism of pOASL against CSFV. We confirmed that CSFV replication was significantly suppressed in lentivirus-delivered, pOASL-overexpressing PK-15 cells, whereas silencing the expression of endogenous pOASL by small interfering RNAs markedly enhanced CSFV growth. In addition, the transcriptional level of pOASL was upregulated both in vitro and in vivo upon CSFV infection. Interestingly, the anti-CSFV effects of pOASL are independent of the canonical RNase L pathway but depend on the activation of the type I IFN response. Glutathione S-transferase pulldown and coimmunoprecipitation assays revealed that pOASL interacts with MDA5, a double-stranded RNA sensor, and further enhances MDA5-mediated type I IFN signaling. Moreover, we showed that pOASL exerts anti-CSFV effects in an MDA5-dependent manner. In conclusion, pOASL suppresses CSFV replication via the MDA5-mediated type I IFN-signaling pathway. IMPORTANCE The host innate immune response plays an important role in mounting the initial resistance to viral infection. Here, we identify the porcine 2′-5′-oligoadenylate synthetase-like protein (pOASL) as an interferon (IFN)-stimulated gene (ISG) against classical swine fever virus (CSFV). We demonstrate that the anti-CSFV effects of pOASL depend on the activation of type I IFN response. In addition, we show that pOASL, as an MDA5-interacting protein, is a coactivator of MDA5-mediated IFN induction to exert anti-CSFV actions. This work will be beneficial to the development of novel anti-CSFV strategies by targeting pOASL.

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Interaction of classical swine fever virus with dendritic cells

Journal of General Virology ◽

10.1099/vir.0.19716-0 ◽

2004 ◽

Vol 85 (6) ◽

pp. 1633-1641 ◽

Cited By ~ 71

Author(s):

C. P. Carrasco ◽

R. C. Rigden ◽

I. E. Vincent ◽

C. Balmelli ◽

M. Ceppi ◽

...

Keyword(s):

Dendritic Cells ◽

T Cell ◽

Classical Swine Fever Virus ◽

Specific Antigen ◽

Classical Swine Fever ◽

Fever Virus ◽

Immune Reactivity ◽

Type I ◽

Antigen Uptake ◽

Polycytidylic Acid

Functional disruption of dendritic cells (DCs) is an important strategy for viral pathogens to evade host defences. Monocytotropic viruses such as classical swine fever virus (CSFV) could employ such a mechanism, since the virus can suppress immune responses and induce apoptosis without infecting lymphocytes. Here, CSFV was shown to infect and efficiently replicate in monocyte- and in bone marrow-derived DCs. Interestingly, the infected DCs displayed neither modulated MHC nor CD80/86 expression. Stimulation of DCs with IFN-α/TNF-α or polyinosinic–polycytidylic acid (pIC) induced phenotypic maturation with increased MHC and CD80/86 expression, both with mock-treated and infected DCs. In addition, the T cell stimulatory capacity of CSFV-infected DCs was maintained both in a polyclonal T cell stimulation and in specific antigen-presentation assays, requiring antigen uptake and processing. Interestingly, similar to macrophages, CSFV did not induce IFN-α responses in these DCs and even suppressed pIC-induced IFN-α induction. Other cytokines including interleukin (IL)-6, IL-10, IL-12 and TNF-α were not modulated. Taken together, these results demonstrated that CSFV can replicate in DCs and control IFN type I responses, without interfering with the immune reactivity. These results are interesting considering that DC infection with RNA viruses usually results in DC activation.

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Role of birds in transmission of classical swine fever virus

Journal of Veterinary Medicine Series B ◽

10.1046/j.1439-0450.2003.00670.x ◽

2003 ◽

Vol 50 (7) ◽

pp. 357-359 ◽

Cited By ~ 8

Author(s):

V. Kaden ◽

E. Lange ◽

H. Steyer ◽

W. Bruer ◽

CH. Langner

Keyword(s):

Classical Swine Fever Virus ◽

Classical Swine Fever ◽

Fever Virus

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A Novel Role of Classical Swine Fever Virus Erns Glycoprotein in Counteracting the Newcastle Disease Virus (NDV)-mediated IFN-β Induction

BMB Reports ◽

10.5483/bmbrep.2007.40.5.611 ◽

2007 ◽

Vol 40 (5) ◽

pp. 611-616 ◽

Cited By ~ 4

Author(s):

Yan-Hua Xia ◽

Liu Chen ◽

Zi-Shu Pan ◽

Chu-Yu Zhang

Keyword(s):

Newcastle Disease Virus ◽

Disease Virus ◽

Classical Swine Fever Virus ◽

Newcastle Disease ◽

Classical Swine Fever ◽

Fever Virus

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Antiviral Role of IFITM Proteins in Classical Swine Fever Virus Infection

Viruses ◽

10.3390/v11020126 ◽

2019 ◽

Vol 11 (2) ◽

pp. 126 ◽

Cited By ~ 10

Author(s):

Cheng Li ◽

Hongqing Zheng ◽

Yifan Wang ◽

Wang Dong ◽

Yaru Liu ◽

...

Keyword(s):

Classical Swine Fever Virus ◽

Mammalian Cells ◽

Classical Swine Fever ◽

Fever Virus ◽

Late Endosomes ◽

Early Endosomes ◽

Infected Cells ◽

The Relationship ◽

Antiviral Role

The proteins IFITM1, IFITM2, and IFITM3 are host effectors against a broad range of RNA viruses whose roles in classical swine fever virus (CSFV) infection had not yet been reported. We investigated the effect of these proteins on CSFV replication in mammalian cells. The proteins were overexpressed and silenced using lentiviruses. Confocal microscopy was used to determine the distribution of these proteins in the cells, and immunofluorescence colocalization analysis was used to evaluate the relationship between IFITMs and the CSFV endosomal pathway, including early endosomes, late endosomes, and lysosomes. IFITM1, IFITM2, or IFITM3 overexpression significantly inhibited CSFV replication, whereas protein knockdown enhanced CSFV replication. In porcine alveolar macrophages (PAMs), IFITM1 was mainly located at the cell surface, whereas IFITM2 and IFITM3 were mainly located in the cytoplasm. Following CSFV infection, the distribution of IFITM1 changed. IFITM1, IFITM2, and IFITM3 colocalization with Lamp1, IFITM2 with Rab5 and Rab7, and IFITM3 with Rab7 were observed in CSFV-infected cells. Collectively, these results provide insights into the possible mechanisms associated with the anti-CSFV action of the IFITM family.

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