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Chen J, Song HX, Hu JH, Bai JS, Li XH, Sun RC, Zhao BQ, Li MZ, Zhou B. Classical swine fever virus non-structural protein 5B hijacks host METTL14-mediated m6A modification to counteract host antiviral immune response. PLoS Pathog 2024; 20:e1012130. [PMID: 38551978 PMCID: PMC11006178 DOI: 10.1371/journal.ppat.1012130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 04/10/2024] [Accepted: 03/17/2024] [Indexed: 04/11/2024] Open
Abstract
Classical Swine Fever (CSF), caused by the Classical Swine Fever Virus (CSFV), inflicts significant economic losses on the global pig industry. A key factor in the challenge of eradicating this virus is its ability to evade the host's innate immune response, leading to persistent infections. In our study, we elucidate the molecular mechanism through which CSFV exploits m6A modifications to circumvent host immune surveillance, thus facilitating its proliferation. We initially discovered that m6A modifications were elevated both in vivo and in vitro upon CSFV infection, particularly noting an increase in the expression of the methyltransferase METTL14. CSFV non-structural protein 5B was found to hijack HRD1, the E3 ubiquitin ligase for METTL14, preventing METTL14 degradation. MeRIP-seq analysis further revealed that METTL14 specifically targeted and methylated TLRs, notably TLR4. METTL14-mediated regulation of TLR4 degradation, facilitated by YTHDF2, led to the accelerated mRNA decay of TLR4. Consequently, TLR4-mediated NF-κB signaling, a crucial component of the innate immune response, is suppressed by CSFV. Collectively, these data effectively highlight the viral evasion tactics, shedding light on potential antiviral strategies targeting METTL14 to curb CSFV infection.
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Affiliation(s)
- Jing Chen
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Hui-xin Song
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Jia-huan Hu
- Guizhou Provincial Center for Disease Control and Prevention, Guiyang, China
| | - Ji-shan Bai
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Xiao-han Li
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Rui-cong Sun
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Bing-qian Zhao
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Mei-zhen Li
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
| | - Bin Zhou
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
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Sun J, Li J, Li L, Yu H, Ma P, Wang Y, Zhu J, Feng Z, Tu C. Classical swine fever virus NS5A protein antagonizes innate immune response by inhibiting the NF-κB signaling. Virol Sin 2023; 38:900-910. [PMID: 37714433 PMCID: PMC10786662 DOI: 10.1016/j.virs.2023.09.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2023] [Accepted: 09/08/2023] [Indexed: 09/17/2023] Open
Abstract
The NS5A non-structural protein of classical swine fever virus (CSFV) is a multifunctional protein involved in viral genomic replication, protein translation, assembly of infectious virus particles, and regulation of cellular signaling pathways. Previous report showed that NS5A inhibited nuclear factor kappa B (NF-κB) signaling induced by poly(I:C); however, the mechanism involved has not been elucidated. Here, we reported that NS5A directly interacted with NF-κB essential modulator (NEMO), a regulatory subunit of the IκB kinase (IKK) complex, to inhibit the NF-κB signaling pathway. Further investigations showed that the zinc finger domain of NEMO and the aa 126-250 segment of NS5A are essential for the interaction between NEMO and NS5A. Mechanistic analysis revealed that NS5A mediated the proteasomal degradation of NEMO. Ubiquitination assay showed that NS5A induced the K27-linked but not the K48-linked polyubiquitination of NEMO for proteasomal degradation. In addition, NS5A blocked the K63-linked polyubiquitination of NEMO, thus inhibiting IKK phosphorylation, IκBα degradation, and NF-κB activation. These findings revealed a novel mechanism by which CSFV inhibits host innate immunity, which might guide the drug design against CSFV in the future.
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Affiliation(s)
- Jinfu Sun
- Key Laboratory of Bioresource Research and Development of Liaoning Province, College of Life and Health Sciences, Northeastern University, Shenyang, 110169, China.
| | - Jiaying Li
- Key Laboratory of Bioresource Research and Development of Liaoning Province, College of Life and Health Sciences, Northeastern University, Shenyang, 110169, China
| | - Liming Li
- Key Laboratory of Bioresource Research and Development of Liaoning Province, College of Life and Health Sciences, Northeastern University, Shenyang, 110169, China
| | - Haixiao Yu
- Key Laboratory of Bioresource Research and Development of Liaoning Province, College of Life and Health Sciences, Northeastern University, Shenyang, 110169, China
| | - Ping Ma
- Key Laboratory of Bioresource Research and Development of Liaoning Province, College of Life and Health Sciences, Northeastern University, Shenyang, 110169, China
| | - Yingnan Wang
- Key Laboratory of Bioresource Research and Development of Liaoning Province, College of Life and Health Sciences, Northeastern University, Shenyang, 110169, China
| | - Jinqi Zhu
- Key Laboratory of Bioresource Research and Development of Liaoning Province, College of Life and Health Sciences, Northeastern University, Shenyang, 110169, China
| | - Zezhong Feng
- Key Laboratory of Bioresource Research and Development of Liaoning Province, College of Life and Health Sciences, Northeastern University, Shenyang, 110169, China
| | - Changchun Tu
- Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun, 130122, China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Disease and Zoonoses, Yangzhou University, Yangzhou, 225009, China.
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Wen S, Li X, Lv X, Liu K, Ren J, Zhai J, Song Y. Current progress on innate immune evasion mediated by Npro protein of pestiviruses. Front Immunol 2023; 14:1136051. [PMID: 37090696 PMCID: PMC10115221 DOI: 10.3389/fimmu.2023.1136051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Accepted: 03/27/2023] [Indexed: 04/08/2023] Open
Abstract
Interferon (IFN), the most effective antiviral cytokine, is involved in innate and adaptive immune responses and is essential to the host defense against virus invasion. Once the host was infected by pathogens, the pathogen-associated molecular patterns (PAMPs) were recognized by the host pattern recognition receptors (PRRs), which activates interferon regulatory transcription factors (IRFs) and nuclear factor-kappa B (NF-κB) signal transduction pathway to induce IFN expression. Pathogens have acquired many strategies to escape the IFN-mediated antiviral immune response. Pestiviruses cause massive economic losses in the livestock industry worldwide every year. The immune escape strategies acquired by pestiviruses during evolution are among the major difficulties in its control. Previous experiments indicated that Erns, as an envelope glycoprotein unique to pestiviruses with RNase activity, could cleave viral ss- and dsRNAs, therefore inhibiting the host IFN production induced by viral ss- and dsRNAs. In contrast, Npro, the other envelope glycoprotein unique to pestiviruses, mainly stimulates the degradation of transcription factor IRF-3 to confront the IFN response. This review mainly summarized the current progress on mechanisms mediated by Npro of pestiviruses to antagonize IFN production.
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Affiliation(s)
- Shubo Wen
- Preventive Veterinary Laboratory, College of Animal Science and Technology, Inner Mongolia Minzu University, Tongliao, China
- Key Laboratory of Zoonose Prevention and Control, Universities of Inner Mongolia Autonomous Region, Tongliao, China
- Beef Cattle Disease Control and Engineering Technology Research Center, Inner Mongolia Autonomous Region, Tongliao, China
| | - Xintong Li
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Xiangyu Lv
- Preventive Veterinary Laboratory, College of Animal Science and Technology, Inner Mongolia Minzu University, Tongliao, China
- Beef Cattle Disease Control and Engineering Technology Research Center, Inner Mongolia Autonomous Region, Tongliao, China
| | - Kai Liu
- Preventive Veterinary Laboratory, College of Animal Science and Technology, Inner Mongolia Minzu University, Tongliao, China
- Beef Cattle Disease Control and Engineering Technology Research Center, Inner Mongolia Autonomous Region, Tongliao, China
| | - Jingqiang Ren
- Wenzhou Key Laboratory for Virology and Immunology, Institute of Virology, Wenzhou University, Zhejiang, Wenzhou, China
- *Correspondence: Jingqiang Ren, ; Jingbo Zhai, ; Yang Song,
| | - Jingbo Zhai
- Preventive Veterinary Laboratory, College of Animal Science and Technology, Inner Mongolia Minzu University, Tongliao, China
- Key Laboratory of Zoonose Prevention and Control, Universities of Inner Mongolia Autonomous Region, Tongliao, China
- *Correspondence: Jingqiang Ren, ; Jingbo Zhai, ; Yang Song,
| | - Yang Song
- Preventive Veterinary Laboratory, College of Animal Science and Technology, Inner Mongolia Minzu University, Tongliao, China
- Key Laboratory of Zoonose Prevention and Control, Universities of Inner Mongolia Autonomous Region, Tongliao, China
- *Correspondence: Jingqiang Ren, ; Jingbo Zhai, ; Yang Song,
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Chen D, Kang H, Tuo T, Wang L, Xia Y, Zhang Y, Zhou L, Ge X, Han J, Guo X, Yang H. Astragalus polysaccharide alleviated the inhibition of CSFV C-strain replication caused by PRRSV via the TLRs/NF‑κB/TNF-α pathways. Virus Res 2022; 319:198854. [PMID: 35788015 DOI: 10.1016/j.virusres.2022.198854] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 06/26/2022] [Accepted: 06/29/2022] [Indexed: 12/22/2022]
Abstract
It is a common phenomenon that PRRSV infection can interfere with the protective efficacy of the CSFV vaccine in clinical settings, and no effective treatment is available. In our previous study, we found that PRRSV infection could inhibit the replication of CSFV-C by promoting the high expression of inflammatory cytokines. In order to further investigate whether Chinese medicine could alleviate the inhibition effect, the PAM39 cells model, which was co-infected with PRRSV and CSFV-C, was established. The effects of Chinese medicine on this co-infection model, as well as the effect of astragalus polysaccharide on the TLRs/NF-κB/TNF-α pathways, were investigated. Our results demonstrated that PAM39 cells inoculated with different pathogenic PRRSV significantly inhibited the replication of CSFV-C and up-regulated the major inflammatory mediators, including TNF-α. For the following studies, 50 µM of astragalus polysaccharide was selected from six kinds of representative Chinese medicine based on their cytotoxicity, viral titers, and inflammatory mediators. Further experiments indicated that astragalus polysaccharide could alleviate the inhibition of CSFV-C replication in the co-infection group with no influence on cell viability. In addition, astragalus polysaccharide treatment clearly reduced P65 phosphorylation and down-regulated the expression of TLR7, TLR9, and TNF-α in co-infection group, implying that the TLRs/NF-κB/TNF-α pathways may play an important role in astragalus polysaccharide's anti-inflammatory response. In conclusion, astragalus polysaccharide treatment alleviated PRRSV-mediated inhibition of CSFV-C replication via the TLRs/NF-κB/TNF-α pathways, and the molecular mechanism of PRRSV co-infection leading to the failure of CSFV vaccine immunization was partially elucidated, providing a scientific basis for effective CSF prevention and control in pig farms.
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Affiliation(s)
- Dengjin Chen
- Department of Preventive Veterinary Medicine, Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, 2 Yuanmingyuan West Road, Haidian District, Beijing 100193, People's Republic of China
| | - Haoran Kang
- Department of Preventive Veterinary Medicine, Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, 2 Yuanmingyuan West Road, Haidian District, Beijing 100193, People's Republic of China
| | - Tianbei Tuo
- Department of Preventive Veterinary Medicine, Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, 2 Yuanmingyuan West Road, Haidian District, Beijing 100193, People's Republic of China
| | - Lihong Wang
- Department of Preventive Veterinary Medicine, Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, 2 Yuanmingyuan West Road, Haidian District, Beijing 100193, People's Republic of China
| | - Yidan Xia
- Department of Preventive Veterinary Medicine, Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, 2 Yuanmingyuan West Road, Haidian District, Beijing 100193, People's Republic of China
| | - Yongning Zhang
- Department of Preventive Veterinary Medicine, Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, 2 Yuanmingyuan West Road, Haidian District, Beijing 100193, People's Republic of China
| | - Lei Zhou
- Department of Preventive Veterinary Medicine, Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, 2 Yuanmingyuan West Road, Haidian District, Beijing 100193, People's Republic of China
| | - Xinna Ge
- Department of Preventive Veterinary Medicine, Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, 2 Yuanmingyuan West Road, Haidian District, Beijing 100193, People's Republic of China
| | - Jun Han
- Department of Preventive Veterinary Medicine, Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, 2 Yuanmingyuan West Road, Haidian District, Beijing 100193, People's Republic of China
| | - Xin Guo
- Department of Preventive Veterinary Medicine, Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, 2 Yuanmingyuan West Road, Haidian District, Beijing 100193, People's Republic of China.
| | - Hanchun Yang
- Department of Preventive Veterinary Medicine, Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, 2 Yuanmingyuan West Road, Haidian District, Beijing 100193, People's Republic of China
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Classical swine fever virus NS4B protein interacts with MAVS and inhibits IL-8 expression in PAMs. Virus Res 2022; 307:198622. [PMID: 34762991 DOI: 10.1016/j.virusres.2021.198622] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 11/03/2021] [Accepted: 11/04/2021] [Indexed: 12/27/2022]
Abstract
Classical swine fever virus (CSFV) infection causes a severe disease of pigs, resulting in significant economic losses. The CSFV NS4B protein is crucial for viral replication and pathogenicity. Interleukin 8 (IL-8), a main chemokine, is induced by multiple cell types and plays an essential role in host defense mechanisms against numerous viruses. It has been reported that NS4A of CSFV is involved in the induction of IL-8 expression in swine umbilical vein endothelial cells. However, the effect of CSFV NS4B on IL-8 expression is unknown. In this study, we showed that CSFV NS4B inhibited IL-8 expression in porcine alveolar macrophages (PAMs), and NS4B inhibited mitochondrial antiviral signaling protein (MAVS)-induced IL-8 expression. Moreover, CSFV NS4B interacted with MAVS. However, NS4B did not alter MAVS expression. Subsequently, we demonstrated that IRF3 knockdown or NF-κB inhibition reduced MAVS-induced IL-8 expression. Furthermore, the IRF3 and NF-κB pathways were activated by MAVS expression. However, CSFV NS4B inhibited MAVS-mediated NF-κB activation and IRF3 expression. Finally, CSFV NS4B inhibited IRF3 expression. Our findings reveal that CSFV NS4B interacts with MAVS and inhibits IL-8 expression by blocking the activation of IRF3 and NF-κB. Taken together, this study provides insights into the mechanism of NS4B-inhibited IL-8 expression.
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Wang X, Gao L, Yang X, Zuo Q, Lan R, Li M, Yang C, Lin Y, Liu J, Yin G. Porcine RACK1 negatively regulates the infection of classical swine fever virus and the NF-κB activation in PK-15 cells. Vet Microbiol 2020; 246:108711. [PMID: 32605753 DOI: 10.1016/j.vetmic.2020.108711] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 04/28/2020] [Accepted: 05/03/2020] [Indexed: 11/15/2022]
Abstract
Classical swine fever (CSF) is one of the main viral diseases of swine worldwide. The causative pathogen is CSF virus (CSFV), a small enveloped RNA virus of the genus Pestivirus. Activation of NF-κB is a hallmark of most viral infections and the viral pathogens frequently kidnap NF-κB pathway for their own advantages, however, it is unclear or even controversial about whether CSFV infection can activate NF-κB signal pathway. RACK1 was shown as an interacting host protein with CSFV NS5A protein, but no studies so far have clearly defined the role of RACK1 during CSFV infection and NF-κB activation. In this study, to properly address these open questions, using RT-qPCR, western blot, indirect fluorescence staining, siRNA knockdown and protein overexpression techniques, we demonstrated that CSFV infection reduced the RACK1 expression at both mRNA and protein levels in PK-15 cells. Downregulation of cellular RACK1 enhanced CSFV infection and subsequent NF-κB activation, while RACK1 overexpression inhibited CSFV infection and the NF-κB activation. In conclusion, RACK1 is a negative cellular regulator for CSFV infection and NF-κB activation in PK-15 cells. Our work addressed a novel aspect concerning the regulation of innate antiviral immune response during CSFV infection. This study may provide some insights into the molecular mechanisms of CSFV infection in swine. However, the elaborate mechanism by which CSFV regulates NF-κB activation and how RACK1 plays its roles in CSFV infection and NF-κB induction require further in-depth studies.
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Affiliation(s)
- Xiaochun Wang
- College of Animal Veterinary Medicine, Yunnan Agricultural University, Kunming, 650201 Yunnan, China
| | - Libo Gao
- College of Animal Veterinary Medicine, Yunnan Agricultural University, Kunming, 650201 Yunnan, China
| | - Xiaoying Yang
- College of Animal Veterinary Medicine, Yunnan Agricultural University, Kunming, 650201 Yunnan, China
| | - Qingwei Zuo
- College of Animal Veterinary Medicine, Yunnan Agricultural University, Kunming, 650201 Yunnan, China
| | - Rui Lan
- College of Animal Veterinary Medicine, Yunnan Agricultural University, Kunming, 650201 Yunnan, China
| | - Miao Li
- College of Animal Veterinary Medicine, Yunnan Agricultural University, Kunming, 650201 Yunnan, China
| | - Chao Yang
- College of Animal Veterinary Medicine, Yunnan Agricultural University, Kunming, 650201 Yunnan, China
| | - Yingbo Lin
- Department of Oncology-Pathology, Karolinska Institute, 17176 Stockholm, Sweden
| | - Jianping Liu
- School of Clinical Medicine, Dali University, Dali 671003, Yunnan, China.
| | - Gefen Yin
- College of Animal Veterinary Medicine, Yunnan Agricultural University, Kunming, 650201 Yunnan, China.
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Chen Y, Fan S, Zhao M, Wu K, Zhu E, Ma S, He W, Deng S, Xu H, Zhang J, Ding H, Yi L, Zhao M, Chen J. MG132 Attenuates the Replication of Classical Swine Fever Virus in vitro. Front Microbiol 2020; 11:852. [PMID: 32582037 PMCID: PMC7283581 DOI: 10.3389/fmicb.2020.00852] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 04/09/2020] [Indexed: 12/21/2022] Open
Abstract
The 26S proteasome, in charge of intracellular protein degradation, plays significant roles in the modulation of various cellular activities as well as in the interplay between virus and host. However, studies about the relationship between 26S proteasome and classical swine fever virus (CSFV) is limited up to now. MG132 is a proteasome inhibitor and has been extensively used in studies about replication of many viruses. Herein, we investigated the role of MG132 in CSFV replication and results showed that MG132 significantly decreased virus titers and viral RNA copies in CSFV-infected PK-15 cells. Further studies demonstrated that MG132 upregulated the expression of several interferon-stimulated genes (ISGs), in CSFV-infected cells. Since the activation of ISGs is controlled by the JAK-STAT signal pathway, we next examined the effect of MG132 on the expression and localization of key molecular STAT1 in the infected cells using Western blot and confocal laser scanning microscopy, respectively. Results showed that CSFV infection and viral NS4A protein decreased the protein level of STAT1, and MG132 promoted the accumulation of STAT1 in the nucleus of cells adjacent to the CSFV-infected cells. Besides, MG132 did not affect the expressions of IFN-α, STAT1, Mx1, OAS1, and PKR genes in cells without CSFV. In conclusion, we identify that MG132 significantly inhibits CSFV replication in vitro, in which the activation of the JAK-STAT pathway and the subsequent upregulation of expressions of ISGs might play significant roles, providing a potential preventive method for CSF.
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Affiliation(s)
- Yuming Chen
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
| | - Shuangqi Fan
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
| | - Mengpo Zhao
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
| | - Keke Wu
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
| | - Erpeng Zhu
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
| | - Shengming Ma
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
| | - Wencheng He
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
| | - Shaofeng Deng
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
| | - Hailuan Xu
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
| | - Jingyuan Zhang
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
| | - Hongxing Ding
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
| | - Lin Yi
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
| | - Mingqiu Zhao
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
| | - Jinding Chen
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
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Npro of Classical Swine Fever Virus Suppresses Type III Interferon Production by Inhibiting IRF1 Expression and Its Nuclear Translocation. Viruses 2019; 11:v11110998. [PMID: 31683525 PMCID: PMC6893713 DOI: 10.3390/v11110998] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Revised: 10/25/2019] [Accepted: 10/29/2019] [Indexed: 12/23/2022] Open
Abstract
Classical swine fever virus (CSFV) causes a contagious disease of pigs. The virus can break the mucosal barrier to establish its infection. Type III interferons (IFN-λs) play a crucial role in maintaining the antiviral state in epithelial cells. Limited information is available on whether or how CSFV modulates IFN-λs production. We found that IFN-λ3 showed dose-dependent suppression of CSFV replication in IPEC-J2 cells. Npro-deleted CSFV mutant (∆Npro) induced significantly higher IFN-λs transcription from 24 h post-infection (hpi) than its parental strain (wtCSFV). The strain wtCSFV strongly inhibited IFN-λs transcription and IFN-λ3 promoter activity in poly(I:C)-stimulated IPEC-J2 cells, whereas ∆Npro did not show such inhibition. Npro overexpression caused significant reduction of IFN-λs transcription and IFN-λ3 promoter activity. Both wtCSFV and ∆Npro infection induced time-dependent IRF1 expression in IPEC-J2 cells, with ΔNpro showing more significant induction, particularly at 24 hpi. However, infection with wtCSFV or Npro overexpression led not only to significant reduction of IRF1 expression and its promoter activity in poly(I:C)-treated IPEC-J2 cells but also to blockage of IRF1 nuclear translocation. This study provides clear evidence that CSFV Npro suppresses IRF1-mediated type III IFNs production by inhibiting IRF1 expression and its nuclear translocation.
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Chen D, Liu X, Xu S, Chen D, Zhou L, Ge X, Han J, Guo X, Yang H. TNF-α induced by porcine reproductive and respiratory syndrome virus inhibits the replication of classical swine fever virus C-strain. Vet Microbiol 2019; 234:25-33. [PMID: 31213269 DOI: 10.1016/j.vetmic.2019.05.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Revised: 05/03/2019] [Accepted: 05/07/2019] [Indexed: 11/16/2022]
Abstract
Porcine productive and respiratory syndrome virus (PRRSV) and classical swine fever virus (CSFV) both are major pathogens of swine that pose a great threat to the Chinese pig industry. It has been found that PRRSV infection can lead to vaccination failure of CSFV C strain-derived modified live vaccine (CSFV-C) by interfering with the immune responses to the latter. To investigate whether PRRSV can suppress CSFV-C replication, we created a 3D4/21-based cell line PAM39 that is susceptible to both viruses by expressing PRRSV receptors CD163 and CD169, and then investigated their interplay under the condition of either sequential or simultaneous co-infection. The most significant suppressive effect came from the sequential infection when the cells were first infected by PRRSV and then followed by CSFV-C at an interval of 6 h. In addition, this effect was independent of PRRSV strains. Mechanistically, PRRSV induced an elevated level of a subset of pro-inflammatory cytokines, especially tumor necrosis factor (TNF-α), through the nuclear factor κB (NF-κB) signaling pathway to inhibit the replication of CSFV-C in vitro. Thus, our studies provide an alternative explanation on PRRSV-induced CSFV vaccination failure, and this has an important implication in CSF vaccination and control.
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Affiliation(s)
- Dongjie Chen
- Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, People's Republic of China
| | - Xiaowen Liu
- Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, People's Republic of China
| | - Shengkui Xu
- Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, People's Republic of China
| | - Dengjin Chen
- Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, People's Republic of China
| | - Lei Zhou
- Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, People's Republic of China
| | - Xinna Ge
- Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, People's Republic of China
| | - Jun Han
- Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, People's Republic of China
| | - Xin Guo
- Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, People's Republic of China.
| | - Hanchun Yang
- Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, 100193, People's Republic of China
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Cao Z, Yang Q, Zheng M, Lv H, Kang K, Zhang Y. Classical swine fever virus non-structural proteins modulate Toll-like receptor signaling pathways in porcine monocyte-derived macrophages. Vet Microbiol 2019; 230:101-109. [PMID: 30827374 DOI: 10.1016/j.vetmic.2019.01.025] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 01/16/2019] [Accepted: 01/27/2019] [Indexed: 12/13/2022]
Abstract
Toll-like receptors (TLRs) are crucial activators of the innate immune response that play various roles in viral infection. Studies have confirmed that classical swine fever virus (CSFV) infection has significant effects on the expression of immune effectors participating in TLR signaling pathways; however, the involvement of CSFV-encoded proteins in TLR signaling pathways remains unclear. In this study, lentiviral individually expressing CSFV non-structural proteins (NSPs) were constructed to identify the "key proteins" that affect TLR gene expression and to analyze the impacts of these proteins on factors downstream of the TLR signaling pathways. The results indicated that Npro, NS2, NS3, NS3/4A, NS4B and NS5A all failed to induce the activation of NF-κB p65. Furthermore, NS4B was found to inhibit poly (I:C) stimulation-mediated activation of the TLR3 signaling pathway in porcine monocyte-derived macrophages (pMDMs), thereby suppressing the TRIF mRNA transcription, the IRF3 protein translation and the NF-κB p65 phosphorylation, and ultimately affecting the secretion of IL-6 and IFN-β; CSFV NS5A protein could significantly increase the activation of MyD88 and IRF7 as well as the consequent synthesis of IFN-α in pMDMs. The results suggest that CSFV NSPs affect TLR-mediated innate immune responses in pMDMs.
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Affiliation(s)
- Zhi Cao
- College of Veterinary Medicine, Northwest A&F University, Shaanxi, 712100, China; Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, 266071, China
| | - Qian Yang
- Key Laboratory of Sustainable Development of Marine Fisheries, Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, 266071, China
| | - Minping Zheng
- College of Veterinary Medicine, Northwest A&F University, Shaanxi, 712100, China
| | - Huifang Lv
- College of Veterinary Medicine, Northwest A&F University, Shaanxi, 712100, China
| | - Kai Kang
- College of Veterinary Medicine, Northwest A&F University, Shaanxi, 712100, China
| | - Yanming Zhang
- College of Veterinary Medicine, Northwest A&F University, Shaanxi, 712100, China.
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11
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Lv H, Dong W, Cao Z, Lin J, Ouyang Y, Guo K, Li C, Zhang Y. Classical swine fever virus non-structural protein 4B binds tank-binding kinase 1. J Biosci 2018; 43:947-957. [PMID: 30541955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Classical swine fever (CSF) is a contagious disease with a high mortality rate and is caused by classical swine fever virus (CSFV). CSFV non-structural protein 4B (NS4B) plays a crucial role in CSFV replication and pathogenicity. However, precisely how NS4B exerts these functions remains unknown, especially as there are no reports relating to potential cellular partners of CSFV NS4B. Here, a yeast two-hybrid (Y2H) system was used to screen the cellular proteins interacting with NS4B from a porcine alveolar macrophage (PAM) cDNA library. The protein screen along with alignment using the NCBI database revealed 14 cellular proteins that interact with NS4B: DDX39B, COX7C, FTH1, MAVS, NR2F6, RPLP1, PSMC4, FGL2, MKRN1, RPL15, RPS3, RAB22A, TP53BP2 and TBK1. These proteins mostly relate to oxidoreductase activity, signal transduction, localization, biological regulation, catalytic activity, transport and metabolism by GO categories. Tank-binding kinase 1 (TBK1) was chosen for further confirmation. The NS4B-TBK1 interaction was further confirmed by subcellular co-location, co-immunoprecipitation and glutathione S-transferase pull-down assays. This study offers a theoretical foundation for further understanding of the diversity of NS4B functions in relation to viral infection and subsequent pathogenesis.
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Affiliation(s)
- Huifang Lv
- College of Veterinary Medicine, Northwest A and F University, No. 22 Xinong Road, Yangling 712100, Shaanxi, China
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12
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Lv H, Dong W, Cao Z, Lin J, Ouyang Y, Guo K, Li C, Zhang Y. Classical swine fever virus non-structural protein 4B binds tank-binding kinase 1. J Biosci 2018. [DOI: 10.1007/s12038-018-9802-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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13
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Qian G, Lv H, Lin J, Li X, Lv Q, Wang T, Zhang J, Dong W, Guo K, Zhang Y. FHC, an NS4B-interacting Protein, Enhances Classical Swine Fever Virus Propagation and Acts Positively in Viral Anti-apoptosis. Sci Rep 2018; 8:8318. [PMID: 29844394 PMCID: PMC5974352 DOI: 10.1038/s41598-018-26777-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 05/02/2018] [Indexed: 01/10/2023] Open
Abstract
Classical swine fever virus (CSFV), the etiological agent of classical swine fever, causes enormous economic loss to the pig industry. Ferritin heavy chain (FHC) is a notable anti-apoptotic protein, and existing evidence suggests that CSFV cannot induce apoptosis of host cells, however, the role of FHC in CSFV replication remains unclear. In the present study, we found that recombinant lentivirus-mediated knockdown or overexpression of FHC inhibited or enhanced CSFV replication, respectively, indicating a positive role for FHC in CSFV proliferation. Furthermore, interaction between the CSFV NS4B protein and FHC was confirmed by glutathione S-transferase (GST) pull-down, co-immunoprecipitation (co-IP) and confocal imaging assays. In addition, both CSFV replication and NS4B expression upregulated expression of FHC, which counteracts apoptosis by modulating cellular reactive oxygen species (ROS). These results suggest that FHC, an NS4B-interacting protein, enhances CSFV replication and has a positive role in viral anti-apoptosis by regulating ROS accumulation. This work may provide a new perspective for understanding the mechanism of CSFV pathogenesis.
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Affiliation(s)
- Gui Qian
- College of Veterinary Medicine, Northwest A&F University, No. 22 Xinong Road, Yangling, 712100, Shaanxi, China
| | - Huifang Lv
- College of Veterinary Medicine, Northwest A&F University, No. 22 Xinong Road, Yangling, 712100, Shaanxi, China
| | - Jihui Lin
- College of Veterinary Medicine, Northwest A&F University, No. 22 Xinong Road, Yangling, 712100, Shaanxi, China
| | - Xiaomeng Li
- College of Veterinary Medicine, Northwest A&F University, No. 22 Xinong Road, Yangling, 712100, Shaanxi, China
| | - Qizhuang Lv
- College of Biology & Pharmacy, Yulin Normal University, No. 1303 Jiaoyu East Road, Yulin, 537000, Guangxi, China
| | - Tao Wang
- College of Veterinary Medicine, Northwest A&F University, No. 22 Xinong Road, Yangling, 712100, Shaanxi, China
| | - Jing Zhang
- College of Veterinary Medicine, Northwest A&F University, No. 22 Xinong Road, Yangling, 712100, Shaanxi, China
| | - Wang Dong
- College of Veterinary Medicine, Northwest A&F University, No. 22 Xinong Road, Yangling, 712100, Shaanxi, China
| | - Kangkang Guo
- College of Veterinary Medicine, Northwest A&F University, No. 22 Xinong Road, Yangling, 712100, Shaanxi, China
| | - Yanming Zhang
- College of Veterinary Medicine, Northwest A&F University, No. 22 Xinong Road, Yangling, 712100, Shaanxi, China.
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Dong W, Lv H, Guo K, Wang T, Ouyang Y, Jin M, Zhang Y. Classical Swine Fever Virus Infection and Its NS4A Protein Expression Induce IL-8 Production through MAVS Signaling Pathway in Swine Umbilical Vein Endothelial Cells. Front Microbiol 2018; 8:2687. [PMID: 29375538 PMCID: PMC5770398 DOI: 10.3389/fmicb.2017.02687] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 12/26/2017] [Indexed: 12/16/2022] Open
Abstract
Classical swine fever virus (CSFV) infection causes a severe disease of pigs, which is characterized by hemorrhage, disseminated intravascular coagulation, and leucopenia. IL-8, a main chemokine and activator of neutrophils, regulates the permeability of endothelium, which may be related to the hemorrhage upon CSFV infection. Until now, the molecular mechanisms of IL-8 regulation during CSFV infection are poorly defined. Here, we showed that CSFV infection induced IL-8 production and the upregulation of IL-8 required virus replication in swine umbilical vein endothelial cells (SUVECs). Additionally, MAVS expression was increased and was required for IL-8 production upon CSFV infection. Moreover, ROS was involved in CSFV-induced IL-8 production. Subsequent studies demonstrated that ROS was involved in MAVS-induced IL-8 production and CSFV induced ROS production through MAVS pathway. These results indicate that CSFV induces IL-8 production through MAVS pathway and production of ROS. The role of NS4A in the pathogenesis of CSFV is not well-understood. In this study, we further demonstrated that CSFV NS4A induced IL-8 production through enhancing MAVS pathway and promoted CSFV replication. In addition, we discovered that CSFV NS4A was localized in the cell nucleus and cytoplasm, including endoplasmic reticulum (ER) and mitochondria. Taken together, these results provide insights into the mechanisms of IL-8 regulation and NS4A functions during CSFV infection.
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Affiliation(s)
- Wang Dong
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Huifang Lv
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Kangkang Guo
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Tao Wang
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Yueling Ouyang
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Mingxing Jin
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
| | - Yanming Zhang
- College of Veterinary Medicine, Northwest A&F University, Yangling, China
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TRAF6 is a novel NS3-interacting protein that inhibits classical swine fever virus replication. Sci Rep 2017; 7:6737. [PMID: 28751780 PMCID: PMC5532216 DOI: 10.1038/s41598-017-06934-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Accepted: 06/21/2017] [Indexed: 12/31/2022] Open
Abstract
Classical swine fever virus (CSFV) non-structural protein 3 (NS3) is a multifunctional non-structural protein that plays a major role in viral replication. However, how exactly NS3 exerts these functions remains unknown. Here, we identified tumour necrosis factor receptor-associated factor 6 (TRAF6) as a novel NS3-interacting protein via yeast two-hybrid analysis, co-immunoprecipitation, and glutathione S-transferase pull-down assays. Furthermore, we observed that TRAF6 overexpression significantly inhibited CSFV replication, and TRAF6 knockdown promoted CSFV replication in porcine alveolar macrophages. Additionally, TRAF6 was degraded during CSFV infection or NS3 expression exclusively, indicating that CSFV and TRAF6 were mutually antagonistic and that TRAF6 degradation might contribute to persistent CSFV replication. Moreover, nuclear factor-kappa B (NF-κB) activity and interferon (IFN)-β and interleukin (IL)-6 expression were increased in TRAF6-overexpressing cells, whereas TRAF6-knockdown cells exhibited decreased NF-κB activity and IFN-β and IL-6 levels. Notably, TRAF6 overexpression did not reduce CSFV replication following inhibition of NF-κB activation by p65 knockdown. Our findings revealed that TRAF6 inhibits CSFV replication via activation of NF-κB-signalling pathways along with increases in the expression of its targets IFN-β and IL-6. This work addresses a novel aspect concerning the regulation of innate antiviral immune response during CSFV infection.
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16
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Cao Z, Liang W, Guo K, Lin Z, Zhang Y, Li H, Zheng M, Zhang C, Ning P, Kang K. A comparison of the impact of Shimen and C strains of classical swine fever virus on Toll-like receptor expression. J Gen Virol 2015; 96:1732-45. [DOI: 10.1099/vir.0.000129] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
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17
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Liu WJ, Yang YT, Zhao MQ, Dong XY, Gou HC, Pei JJ, Chen JD. PKR activation enhances replication of classical swine fever virus in PK-15 cells. Virus Res 2015; 204:47-57. [PMID: 25899421 PMCID: PMC7114430 DOI: 10.1016/j.virusres.2015.04.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 03/25/2015] [Accepted: 04/09/2015] [Indexed: 12/22/2022]
Abstract
CSFV infection triggers PKR and eIF2α protein phosphorylation. PKR overexpression stimulates viral replication. PKR depletion blocks eIF2α phosphorylation and suppresses viral replication. PKR depletion increases IFN-β, and enhances the antiviral effect of IFN.
Classical swine fever (CSF) is a highly contagious swine disease that is responsible for economic losses worldwide. Protein kinase R (PK)R is an important protein in the host viral response; however, the role of PKR in CSFV infection remains unknown. This issue was addressed in the present study using the PK-15 swine kidney cell line. We found that CSFV infection increased the phosphorylation of eukaryotic translation initiation factor (eIF)2α and its kinase PKR. However, the expression of viral proteins continued to increase. Furthermore, PKR overexpression enhanced CSFV replication, while PKR inhibition resulted in reduced CSFV replication and an increase in interferon (IFN) induction. In addition, PKR was responsible for eIF2α phosphorylation in CSFV-infected cells. These results suggest that the activation of PKR during CSFV infection is beneficial to the virus. The virus is able to commandeer the host cell's translation machinery for viral protein synthesis while evading innate immune defenses.
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Affiliation(s)
- Wen-Jun Liu
- College of Veterinary Medicine, South China Agricultural University, 483 Wu Shan Road, Tian He District, Guangzhou 510642, China
| | - You-Tian Yang
- College of Veterinary Medicine, South China Agricultural University, 483 Wu Shan Road, Tian He District, Guangzhou 510642, China
| | - Ming-Qiu Zhao
- College of Veterinary Medicine, South China Agricultural University, 483 Wu Shan Road, Tian He District, Guangzhou 510642, China
| | - Xiao-Ying Dong
- College of Veterinary Medicine, South China Agricultural University, 483 Wu Shan Road, Tian He District, Guangzhou 510642, China
| | - Hong-Chao Gou
- College of Veterinary Medicine, South China Agricultural University, 483 Wu Shan Road, Tian He District, Guangzhou 510642, China
| | - Jing-Jing Pei
- College of Veterinary Medicine, South China Agricultural University, 483 Wu Shan Road, Tian He District, Guangzhou 510642, China
| | - Jin-Ding Chen
- College of Veterinary Medicine, South China Agricultural University, 483 Wu Shan Road, Tian He District, Guangzhou 510642, China.
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18
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Dong XY, Liu WJ, Zhao MQ, Wang JY, Pei JJ, Luo YW, Ju CM, Chen JD. Classical swine fever virus triggers RIG-I and MDA5-dependent signaling pathway to IRF-3 and NF-κB activation to promote secretion of interferon and inflammatory cytokines in porcine alveolar macrophages. Virol J 2013; 10:286. [PMID: 24034559 PMCID: PMC3849481 DOI: 10.1186/1743-422x-10-286] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Accepted: 07/24/2013] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Classical swine fever (CSF) caused by CSF virus (CSFV) is a highly contagious disease of pigs. The RNA helicases retinoic acid-inducible gene I (RIG-I) and melanoma differentiation-associated gene 5 (MDA-5) are differentially involved in the detection of various RNA viruses. In present study, we investigated the roles of RIG-I and MDA-5 in eliciting antiviral and inflammatory responses to CSFV shimen strain in Porcine alveolar macrophages (PAMs). METHODS CSFV Shimen strain was used as challenge virus in this study and PAMs were cultured in vitro. Interferon regulatory factor (IRF)-3 and nuclear factor-kappa B (NF-κB) translocation was detected using immunofluorescent staining; RIG-I, MDA5, interferon promoter-stimulating factor 1 (IPS-1), IRF-3 and NF-κB expression was measured by Western Blotting; Interferon beta (IFN-β), IFN-α, interleukin-1beta (IL-1β), IL-6 and tumor necrosis factor (TNF-α) expression was tested by Enzyme-linked immunosorbent assays (ELISA) and shRNA-mediated knockdown of MDA5 or RIG-I was performed. RESULTS The findings suggested that the initial response to CSFV infection resulted in the higher expression of RIG-I and MDA5 leading to the activation of IPS-1, IRF-3 and NF-κB in a dose-dependent manner. Evaluation of IFN-α, IFN-β, IL-1β, IL-6 or TNF-α expressed by PAMs showed significant differences between infected and uninfected cells. CSFV infected cells induced to express high levels of IFN-α, IFN-β, IL-1β, IL-6 and TNF-α in a dose-dependent way within 24 h post-infection (hpi). At the same time, CSFV improved the nuclear translocation of IRF-3 and NF-κB. We also directly compared and assessed the roles of RIG-I and MDA5 in triggering innate immune actions during CSFV infection through shRNA-mediated knockdown of MDA5 or RIG-I. We found that, compared to the control, the production of IFN-α, IFN-β, IL-1β, IL-6 and TNF-α in response to CSFV infection was heavily reduced in RIG-I knockdown cells while it was moderately decreased in MDA5 knockdown cells. PAMs derived from knockdown of both RIG-I and MDA5 almost failed to produce IFNs and inflammatory cytokines. CONCLUSIONS It indicates that CSFV can be recognized by both RIG-I and MDA5 to initiate the RIG-I signaling pathway to trigger innate defenses against infection.
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Affiliation(s)
- Xiao-Ying Dong
- College of Veterinary Medicine, South China Agricultural University, No.483 Wu Shan Road, Tian He District, Guangzhou 510642, China
- College of Yingdong Agricultural Science and Engineering, Shaoguan University, Daxue Avenue, Zhenjiang District, Shaoguan 512005, China
| | - Wen-Jun Liu
- College of Veterinary Medicine, South China Agricultural University, No.483 Wu Shan Road, Tian He District, Guangzhou 510642, China
| | - Ming-Qiu Zhao
- College of Veterinary Medicine, South China Agricultural University, No.483 Wu Shan Road, Tian He District, Guangzhou 510642, China
| | - Jia-Ying Wang
- College of Veterinary Medicine, South China Agricultural University, No.483 Wu Shan Road, Tian He District, Guangzhou 510642, China
| | - Jing-Jing Pei
- College of Veterinary Medicine, South China Agricultural University, No.483 Wu Shan Road, Tian He District, Guangzhou 510642, China
| | - Yong-Wen Luo
- College of Veterinary Medicine, South China Agricultural University, No.483 Wu Shan Road, Tian He District, Guangzhou 510642, China
| | - Chun-Mei Ju
- College of Veterinary Medicine, South China Agricultural University, No.483 Wu Shan Road, Tian He District, Guangzhou 510642, China
| | - Jin-Ding Chen
- College of Veterinary Medicine, South China Agricultural University, No.483 Wu Shan Road, Tian He District, Guangzhou 510642, China
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