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Zhou CM, Jiang ZZ, Liu N, Yu XJ. Current insights into human pathogenic phenuiviruses and the host immune system. Virulence 2024; 15:2384563. [PMID: 39072499 PMCID: PMC11290763 DOI: 10.1080/21505594.2024.2384563] [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: 05/22/2024] [Revised: 07/09/2024] [Accepted: 07/18/2024] [Indexed: 07/30/2024] Open
Abstract
Phenuiviruses are a class of segmented negative-sense single-stranded RNA viruses, typically consisting of three RNA segments that encode four distinct proteins. The emergence of pathogenic phenuivirus strains, such as Rift Valley fever phlebovirus (RVFV) in sub-Saharan Africa, Severe Fever with Thrombocytopenia Syndrome Virus (SFTSV) in East and Southeast Asia, and Heartland Virus (HRTV) in the United States has presented considerable challenges to global public health in recent years. The innate immune system plays a crucial role as the initial defense mechanism of the host against invading pathogens. In addition to continued research aimed at elucidating the epidemiological characteristics of phenuivirus, significant advancements have been made in investigating its viral virulence factors (glycoprotein, non-structural protein, and nucleoprotein) and potential host-pathogen interactions. Specifically, efforts have focused on understanding mechanisms of viral immune evasion, viral assembly and egress, and host immune networks involving immune cells, programmed cell death, inflammation, nucleic acid receptors, etc. Furthermore, a plethora of technological advancements, including metagenomics, metabolomics, single-cell transcriptomics, proteomics, gene editing, monoclonal antibodies, and vaccines, have been utilized to further our understanding of phenuivirus pathogenesis and host immune responses. Hence, this review aims to provide a comprehensive overview of the current understanding of the mechanisms of host recognition, viral immune evasion, and potential therapeutic approaches during human pathogenic phenuivirus infections focusing particularly on RVFV and SFTSV.
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Affiliation(s)
- Chuan-Min Zhou
- Gastrointestinal Disease Diagnosis and Treatment Center, The First Hospital of Hebei Medical University, Shijiazhuang, China
- Department of General Surgery, Hebei Key Laboratory of Colorectal Cancer Precision Diagnosis and Treatment, The First Hospital of Hebei Medical University, Shijiazhuang, China
- Central Laboratory, The First Hospital of Hebei Medical University, Shijiazhuang, China
| | - Ze-Zheng Jiang
- State Key Laboratory of Virology, School of Public Health, Wuhan University, Wuhan, China
| | - Ning Liu
- Department of Quality and Operations Management, The First Hospital of Hebei Medical University, Shijiazhuang, China
| | - Xue-Jie Yu
- State Key Laboratory of Virology, School of Public Health, Wuhan University, Wuhan, China
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Jiang ZZ, Chu M, Yan LN, Zhang WK, Li B, Xu J, Zhao ZX, Han HJ, Zhou CM, Yu XJ. SFTSV nucleoprotein mediates DNA sensor cGAS degradation to suppress cGAS-dependent antiviral responses. Microbiol Spectr 2024; 12:e0379623. [PMID: 38712963 DOI: 10.1128/spectrum.03796-23] [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: 11/09/2023] [Accepted: 03/28/2024] [Indexed: 05/08/2024] Open
Abstract
Cyclic GMP-AMP synthase (cGAS) is an important DNA pattern recognition receptor that senses double-stranded DNA derived from invading pathogens or self DNA in cytoplasm, leading to an antiviral interferon response. A tick-borne Bunyavirus, severe fever with thrombocytopenia syndrome virus (SFTSV), is an RNA virus that causes a severe emerging viral hemorrhagic fever in Asia with a high case fatality rate of up to 30%. However, it is unclear whether cGAS interacts with SFTSV infection. In this study, we found that SFTSV infection upregulated cGAS RNA transcription and protein expression, indicating that cGAS is an important innate immune response against SFTSV infection. The mechanism of cGAS recognizing SFTSV is by cGAS interacting with misplaced mitochondrial DNA in the cytoplasm. Depletion of mitochondrial DNA significantly inhibited cGAS activation under SFTSV infection. Strikingly, we found that SFTSV nucleoprotein (N) induced cGAS degradation in a dose-dependent manner. Mechanically, N interacted with the 161-382 domain of cGAS and linked the cGAS to LC3. The cGAS-N-LC3 trimer was targeted to N-induced autophagy, and the cGAS was degraded in autolysosome. Taken together, our study discovered a novel antagonistic mechanism of RNA viruses, SFTSV is able to suppress the cGAS-dependent antiviral innate immune responses through N-hijacking cGAS into N-induced autophagy. Our results indicated that SFTSV N is an important virulence factor of SFTSV in mediating host antiviral immune responses. IMPORTANCE Severe fever with thrombocytopenia syndrome virus (SFTSV) is a tick-borne RNA virus that is widespread in East and Southeast Asian countries with a high fatality rate of up to 30%. Up to now, many cytoplasmic pattern recognition receptors, such as RIG-I, MDA5, and SAFA, have been reported to recognize SFTSV genomic RNA and trigger interferon-dependent antiviral responses. However, current knowledge is not clear whether SFTSV can be recognized by DNA sensor cyclic GMP-AMP synthase (cGAS). Our study demonstrated that cGAS could recognize SFTSV infection via ectopic mitochondrial DNA, and the activated cGAS-stimulator of interferon genes signaling pathway could significantly inhibit SFTSV replication. Importantly, we further uncovered a novel mechanism of SFTSV to inhibit innate immune responses by the degradation of cGAS. cGAS was degraded in N-induced autophagy. Collectively, this study illustrated a novel virulence factor of SFTSV to suppress innate immune responses through autophagy-dependent cGAS degradation.
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Affiliation(s)
- Ze-Zheng Jiang
- State Key Laboratory of Virology, School of Public Health, Wuhan University, Wuhan, Hubei, China
| | - Min Chu
- Reproductive Medicine Center, The Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, Shandong, China
| | - Li-Na Yan
- State Key Laboratory of Virology, School of Public Health, Wuhan University, Wuhan, Hubei, China
| | - Wen-Kang Zhang
- State Key Laboratory of Virology, School of Public Health, Wuhan University, Wuhan, Hubei, China
| | - Bang Li
- State Key Laboratory of Virology, School of Public Health, Wuhan University, Wuhan, Hubei, China
| | - Jiao Xu
- State Key Laboratory of Virology, School of Public Health, Wuhan University, Wuhan, Hubei, China
| | - Zhong-Xin Zhao
- Department of Laboratory Medicine, Linyi People's Hospital, Linyi, Shandong, China
| | - Hui-Ju Han
- School of Public Health, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, Shandong, China
| | - Chuan-Min Zhou
- State Key Laboratory of Virology, School of Public Health, Wuhan University, Wuhan, Hubei, China
| | - Xue-Jie Yu
- State Key Laboratory of Virology, School of Public Health, Wuhan University, Wuhan, Hubei, China
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Yoneyama M, Kato H, Fujita T. Physiological functions of RIG-I-like receptors. Immunity 2024; 57:731-751. [PMID: 38599168 DOI: 10.1016/j.immuni.2024.03.003] [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: 01/20/2024] [Revised: 02/19/2024] [Accepted: 03/04/2024] [Indexed: 04/12/2024]
Abstract
RIG-I-like receptors (RLRs) are crucial for pathogen detection and triggering immune responses and have immense physiological importance. In this review, we first summarize the interferon system and innate immunity, which constitute primary and secondary responses. Next, the molecular structure of RLRs and the mechanism of sensing non-self RNA are described. Usually, self RNA is refractory to the RLR; however, there are underlying host mechanisms that prevent immune reactions. Studies have revealed that the regulatory mechanisms of RLRs involve covalent molecular modifications, association with regulatory factors, and subcellular localization. Viruses have evolved to acquire antagonistic RLR functions to escape the host immune reactions. Finally, the pathologies caused by the malfunction of RLR signaling are described.
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Affiliation(s)
- Mitsutoshi Yoneyama
- Division of Molecular Immunology, Medical Mycology Research Center, Chiba University, Chiba, Japan; Division of Pandemic and Post-disaster Infectious Diseases, Research Institute of Disaster Medicine, Chiba University, Chiba, Japan
| | - Hiroki Kato
- Institute of Cardiovascular Immunology, Medical Faculty, University Hospital Bonn, University of Bonn, Bonn, Germany
| | - Takashi Fujita
- Institute of Cardiovascular Immunology, Medical Faculty, University Hospital Bonn, University of Bonn, Bonn, Germany; Laboratory of Regulatory Information, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto, Japan.
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An H, Yu X, Liu Y, Fang L, Shu M, Zhai Q, Chen J. Downregulation of transcription 1 hinders the replication of Dabie bandavirus by promoting the expression of TLR7, TLR8, and TLR9 signaling pathway. Ticks Tick Borne Dis 2024; 15:102307. [PMID: 38194758 DOI: 10.1016/j.ttbdis.2023.102307] [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: 04/12/2023] [Revised: 12/15/2023] [Accepted: 12/28/2023] [Indexed: 01/11/2024]
Abstract
Severe fever with thrombocytopenia syndrome virus (SFTSV) is a bunyavirus that causes SFTS, with a case fatality rate of up to 30 %. The innate immune system plays a crucial role in the defense against SFTSV; however, the impact of viral propagation of STFSV on the innate immune system remains unclear. Although proteomics analysis revealed that the expression of the downregulator of transcription 1 (DR1) increased after SFTSV infection, the specific change trend and the functional role of DR1 during viral infection remain unelucidated. In this study, we demonstrate that DR1 was highly expressed in response to SFTSV infection in HEK 293T cells using qRT-PCR and Western blot analysis. Furthermore, viral replication significantly increased the expression of various TLRs, especially TLR9. Our data indicated that DR1 positively regulated the expression of TLRs in HEK 293T cells, DR1 overexpression highly increased the expression of numerous TLRs, whereas RNAi-mediated DR1 silencing decreased TLR expression. Additionally, the myeloid differentiation primary response gene 88 (MyD88)-dependent or TIR-domain-containing adaptor inducing interferon-β (TRIF)-dependent signaling pathways were highly up- and downregulated by the overexpression and silencing of DR1, respectively. Finally, we report that DR1 stimulates the expression of TLR7, TLR8, and TLR9, thereby upregulating the TRIF-dependent and MyD88-dependent signaling pathways during the SFTSV infection, attenuating viral replication, and enhancing the production of type I interferon and various inflammatory factors, including IL-1β, IL-6, and IL-8. These results imply that DR1 defends against SFTSV replication by inducing the expression of TLR7, TLR8, and TLR9. Collectively, our findings revealed a novel role and mechanism of DR1 in mediating antiviral responses and innate immunity.
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Affiliation(s)
- Hao An
- School of Public Health, Weifang Medical University, Weifang 261053, China
| | - Xiaoli Yu
- School of Public Health, Weifang Medical University, Weifang 261053, China
| | - Yumei Liu
- School of Public Health, Weifang Medical University, Weifang 261053, China
| | - Lei Fang
- School of Public Health, Weifang Medical University, Weifang 261053, China
| | - Ming Shu
- School of Public Health, Weifang Medical University, Weifang 261053, China
| | - Qingfeng Zhai
- School of Public Health, Weifang Medical University, Weifang 261053, China
| | - Junhao Chen
- School of Public Health, Weifang Medical University, Weifang 261053, China.
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Zhu J, Chiang C, Gack MU. Viral evasion of the interferon response at a glance. J Cell Sci 2023; 136:jcs260682. [PMID: 37341132 PMCID: PMC10411950 DOI: 10.1242/jcs.260682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/22/2023] Open
Abstract
Re-emerging and new viral pathogens have caused significant morbidity and mortality around the world, as evidenced by the recent monkeypox, Ebola and Zika virus outbreaks and the ongoing COVID-19 pandemic. Successful viral infection relies on tactical viral strategies to derail or antagonize host innate immune defenses, in particular the production of type I interferons (IFNs) by infected cells. Viruses can thwart intracellular sensing systems that elicit IFN gene expression (that is, RIG-I-like receptors and the cGAS-STING axis) or obstruct signaling elicited by IFNs. In this Cell Science at a Glance article and the accompanying poster, we review the current knowledge about the major mechanisms employed by viruses to inhibit the activity of intracellular pattern-recognition receptors and their downstream signaling cascades leading to IFN-based antiviral host defenses. Advancing our understanding of viral immune evasion might spur unprecedented opportunities to develop new antiviral compounds or vaccines to prevent viral infectious diseases.
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Affiliation(s)
- Junji Zhu
- Florida Research and Innovation Center, Cleveland Clinic, Port St. Lucie, FL 34987, USA
| | - Cindy Chiang
- Florida Research and Innovation Center, Cleveland Clinic, Port St. Lucie, FL 34987, USA
| | - Michaela U. Gack
- Florida Research and Innovation Center, Cleveland Clinic, Port St. Lucie, FL 34987, USA
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Yoshikawa R, Kawakami M, Yasuda J. The NSs protein of severe fever with thrombocytopenia syndrome virus differentially inhibits the type 1 interferon response among animal species. J Biol Chem 2023:104819. [PMID: 37187292 DOI: 10.1016/j.jbc.2023.104819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2022] [Revised: 05/07/2023] [Accepted: 05/08/2023] [Indexed: 05/17/2023] Open
Abstract
Severe fever with thrombocytopenia syndrome virus (SFTSV), which has been reported in China, Korea, Japan, Vietnam, and Taiwan, is a causative agent of severe fever thrombocytopenia syndrome (SFTS). This virus has a high mortality and induces thrombocytopenia and leukocytopenia in humans, cats, and aged ferrets, whereas immunocompetent adult mice infected with SFTSV never show symptoms. Anti-SFTSV antibodies have been detected in several animals- including goats, sheep, cattle, and pigs. However, there are no reports of SFTS in these animals. Previous studies have reported that the nonstructural protein NSs of SFTSV inhibits the type I interferon (IFN-I) response through the sequestration of human signal transducer and activator of transcription (STAT) proteins. In this study, comparative analysis of the function of NSs as IFN antagonists in human, cat, dog, ferret, mouse, and pig cells revealed a correlation between pathogenicity of SFTSV and the function of NSs in each animal. Furthermore, we found that the inhibition of IFN-I signaling and phosphorylation of STAT1 and STAT2 by NSs depended on the binding ability of NSs to STAT1 and STAT2. Our results imply that the function of NSs in antagonizing STAT2 determines the species-specific pathogenicity of SFTSV.
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Affiliation(s)
- Rokusuke Yoshikawa
- Department of Emerging Infectious Diseases, Institute of Tropical Medicine (NEKKEN); National Research Center for the Control and Prevention of Infectious Diseases (CCPID)
| | - Masahiro Kawakami
- Department of Emerging Infectious Diseases, Institute of Tropical Medicine (NEKKEN)
| | - Jiro Yasuda
- Department of Emerging Infectious Diseases, Institute of Tropical Medicine (NEKKEN); National Research Center for the Control and Prevention of Infectious Diseases (CCPID); Graduate School of Biomedical Sciences and Program for Nurturing Global Leaders in Tropical and Emerging Communicable Diseases, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan.
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Liu S, Su Y, Lu Z, Zou X, Xu L, Teng Y, Wang Z, Wang T. The SFTSV Nonstructural Proteins Induce Autophagy to Promote Viral Replication via Interaction with Vimentin. J Virol 2023; 97:e0030223. [PMID: 37039677 PMCID: PMC10134822 DOI: 10.1128/jvi.00302-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Accepted: 03/20/2023] [Indexed: 04/12/2023] Open
Abstract
Severe fever with thrombocytopenia syndrome virus (SFTSV) is a newly identified phlebovirus associated with severe hemorrhagic fever in humans. Studies have shown that SFTSV nucleoprotein (N) induces BECN1-dependent autophagy to promote viral assembly and release. However, the function of other SFTSV proteins in regulating autophagy has not been reported. In this study, we identify SFTSV NSs, a nonstructural protein that forms viroplasm-like structures in the cytoplasm of infected cells as the virus component mediating SFTSV-induced autophagy. We found that SFTSV NSs-induced autophagy was inclusion body independent, and most phenuivirus NSs had autophagy-inducing effects. Unlike N protein-induced autophagy, SFTSV NSs was key in regulating autophagy by interacting with the host's vimentin in an inclusion body-independent manner. NSs interacted with vimentin and induced vimentin degradation through the K48-linked ubiquitin-proteasome pathway. This negatively regulating Beclin1-vimentin complex formed and promoted autophagy. Furthermore, we identified the NSs-binding domain of vimentin and found that overexpression of wild-type vimentin antagonized the induced effect of NSs on autophagy and inhibited viral replication, suggesting that vimentin is a potential antiviral target. The present study shows a novel mechanism through which SFTSV nonstructural protein activates autophagy, which provides new insights into the role of NSs in SFTSV infection and pathogenesis. IMPORTANCE Severe fever with thrombocytopenia syndrome virus (SFTSV) is a newly emerging tick-borne pathogen that causes multifunctional organ failure and even death in humans. As a housekeeping mechanism for cells to maintain steady state, autophagy plays a dual role in viral infection and the host's immune response. However, the relationship between SFTSV infection and autophagy has not been described in detail yet. Here, we demonstrated that SFTSV infection induced complete autophagic flux and facilitated viral proliferation. We also identified a key mechanism underlying NSs-induced autophagy, in which NSs interacted with vimentin to inhibit the formation of the Beclin1-vimentin complex and induced vimentin degradation through K48-linked ubiquitination modification. These findings may help us understand the new functions and mechanisms of NSs and may aid in the identification of new antiviral targets.
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Affiliation(s)
- Sihua Liu
- School of Life Sciences, Tianjin University, Tianjin, China
| | - Yazhi Su
- School of Life Sciences, Tianjin University, Tianjin, China
| | - Zhuozhuang Lu
- National Institute for Viral Disease Control and Prevention, CDC, Beijing, China
| | - Xiaohui Zou
- National Institute for Viral Disease Control and Prevention, CDC, Beijing, China
| | - Leling Xu
- School of Life Sciences, Tianjin University, Tianjin, China
| | - Yue Teng
- State Key Laboratory of Pathogen and Biosecurity Beijing Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences, Beijing, China
| | - Zhiyun Wang
- School of Environmental Science and Engineering, Tianjin University, Tianjin, China
| | - Tao Wang
- School of Life Sciences, Tianjin University, Tianjin, China
- Institute of Tianjin Key Laboratory of Function and Application of Biological Macromolecular Structures, Tianjin, China
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Fares M, Brennan B. Virus-host interactions during tick-borne bunyavirus infection. Curr Opin Virol 2022; 57:101278. [PMID: 36375406 DOI: 10.1016/j.coviro.2022.101278] [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: 08/03/2022] [Revised: 09/21/2022] [Accepted: 10/20/2022] [Indexed: 11/13/2022]
Abstract
The Bunyavirales order is the largest grouping of RNA viruses, comprising emerging and re-emerging human, plant and animal pathogens. Bunyaviruses have a global distribution and many members of the order are transmitted by arthropods. They have evolved a plethora of mechanisms to manipulate the regulatory processes of the infected cell to facilitate their own replicative cycle, in hosts of disparate phylogenies. Interest in virus-vector interactions is growing rapidly. However, current understanding of tick-borne bunyavirus cellular interaction is heavily biased to studies conducted in mammalian systems. In this short review, we summarise current understandings of how tick-borne bunyaviruses utilise major cellular pathways (innate immunity, apoptosis and RNAi responses) in mammalian or tick cells to facilitate virus replication.
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Affiliation(s)
- Mazigh Fares
- Medical Research Council-University of Glasgow Centre for Virus Research, Glasgow G61 1QH, Scotland, UK
| | - Benjamin Brennan
- Medical Research Council-University of Glasgow Centre for Virus Research, Glasgow G61 1QH, Scotland, UK.
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Wang T, Xu L, Zhu B, Wang J, Zheng X. Immune escape mechanisms of severe fever with thrombocytopenia syndrome virus. Front Immunol 2022; 13:937684. [PMID: 35967309 PMCID: PMC9366518 DOI: 10.3389/fimmu.2022.937684] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 07/04/2022] [Indexed: 11/13/2022] Open
Abstract
Severe fever with thrombocytopenia syndrome (SFTS), which is caused by SFTS virus (SFTSV), poses a serious threat to global public health, with high fatalities and an increasing prevalence. As effective therapies and prevention strategies are limited, there is an urgent need to elucidate the pathogenesis of SFTS. SFTSV has evolved several mechanisms to escape from host immunity. In this review, we summarize the mechanisms through which SFTSV escapes host immune responses, including the inhibition of innate immunity and evasion of adaptive immunity. Understanding the pathogenesis of SFTS will aid in the development of new strategies for the treatment of this disease.
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Affiliation(s)
- Tong Wang
- Department of Infectious Diseases, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Joint International Laboratory of Infection and Immunity, Huazhong University of Science and Technology, Wuhan, China
| | - Ling Xu
- Department of Infectious Diseases, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Joint International Laboratory of Infection and Immunity, Huazhong University of Science and Technology, Wuhan, China
| | - Bin Zhu
- Department of Infectious Diseases, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Joint International Laboratory of Infection and Immunity, Huazhong University of Science and Technology, Wuhan, China
| | - Junzhong Wang
- Department of Infectious Diseases, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Joint International Laboratory of Infection and Immunity, Huazhong University of Science and Technology, Wuhan, China
- *Correspondence: Junzhong Wang, ; Xin Zheng,
| | - Xin Zheng
- Department of Infectious Diseases, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Joint International Laboratory of Infection and Immunity, Huazhong University of Science and Technology, Wuhan, China
- *Correspondence: Junzhong Wang, ; Xin Zheng,
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Dabie bandavirus Nonstructural Protein Interacts with Actin to Induce F-Actin Rearrangement and Inhibit Viral Adsorption and Entry. J Virol 2022; 96:e0078822. [PMID: 35862701 PMCID: PMC9327694 DOI: 10.1128/jvi.00788-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Dabie bandavirus (DBV) is an emerging Bandavirus that causes multiorgan failure with a high fatality rate in humans. While many viruses can manipulate the actin cytoskeleton to facilitate viral growth, the regulation pattern of the actin cytoskeleton and the molecular mechanisms involved in DBV entry into the host cells remain unclear. In this study, we demonstrate that expression of nonstructural protein (NSs) or infection with DBV induces actin rearrangement, which presents a point-like distribution, and this destruction is dependent on inclusion bodies (IBs). Further experiments showed that NSs inhibits viral adsorption by destroying the filopodium structure. In addition, NSs also compromised the viral entry by inhibiting clathrin aggregation on the cell surface and capturing clathrin into IBs. Furthermore, NSs induced clathrin light chain B (CLTB) degradation through the K48-linked ubiquitin proteasome pathway, which could negatively regulate clathrin-mediated endocytosis, inhibiting the viral entry. Finally, we confirmed that this NSs-induced antiviral mechanism is broadly applicable to other viruses, such as enterovirus 71 (EV71) and influenza virus, A/PR8/34 (PR8), which use the same clathrin-mediated endocytosis to enter host cells. In conclusion, our study provides new insights into the role of NSs in inhibiting endocytosis and a novel strategy for treating DBV infections. IMPORTANCEDabie bandavirus (DBV), a member of the Phenuiviridae family, is a newly emerging tick-borne pathogen that causes multifunctional organ failure and even death in humans. The actin cytoskeleton is involved in various crucial cellular processes and plays an important role in viral life activities. However, the relationship between DBV infection and the actin cytoskeleton has not been described in detail. Here, we show for the first time the interaction between NSs and actin to induce actin rearrangement, which inhibits the viral adsorption and entry. We also identify a key mechanism underlying NSs-induced entry inhibition in which NSs prevents clathrin aggregation on the cell surface by hijacking clathrin into the inclusion body and induces CLTB degradation through the K48-linked ubiquitination modification. This paper is the first to reveal the antiviral mechanism of NSs and provides a theoretical basis for the search for new antiviral targets.
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Nonstructural Protein NSs Activates Inflammasome and Pyroptosis through Interaction with NLRP3 in Human Microglial Cells Infected with Severe Fever with Thrombocytopenia Syndrome Bandavirus. J Virol 2022; 96:e0016722. [PMID: 35695505 PMCID: PMC9278151 DOI: 10.1128/jvi.00167-22] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Severe fever with thrombocytopenia syndrome (SFTS) is a tick-borne febrile disease caused by SFTS virus (SFTSV), or Dabie bandavirus, in the Phenuiviridae family. Clinically neurological disorders in SFTS have been commonly reported, but their neuropathogenesis has rarely been studied. Microglia are a type of neuroglia accounting for 10 to 12% of all cells in the brain. As resident immune cells, microglial cells are the first line of immune defense present in the central nervous system (CNS). Here, we report that SFTSV was able to infect microglial cells and stimulate interleukin 1β (IL-1β) secretion in the brains of infected neonatal BALB/c mice. We characterized the cell death induced in infected human microglial HMC3 cells, also susceptible to SFTSV, and found that the NOD-like receptor protein 3 (NLRP3) inflammasome was activated, leading to secretion of IL-1β and pyroptosis. Knockdown of NLRP3 or inhibition of the NLRP3 inflammasome activation suppressed the viral replication, suggesting that the activation of the NLRP3 inflammasome may support SFTSV replication in microglial cells. Viral nonstructural protein NSs, a known modulator of immune responses, interacted and colocalized with NLRP3 for the inflammasome activation. It appeared that the N-terminal fragment, amino acids 1 to 66, of NSs was critical to promote the assembly of the inflammasome complex by interacting with NLRP3 for its activation in microglial cells. Our findings provide evidence that SFTSV may cause neurological disorders through infecting microglia and activating the inflammasome through its nonstructural protein NSs for neural cell death and inflammation. This study may have revealed a novel mechanism of SFTSV NSs in dysregulating host response. IMPORTANCE Encephalitis or encephalopathy during severe fever with thrombocytopenia syndrome (SFTS) is considered a critical risk factor leading to high mortality, but there have been no studies to date on the pathogenesis of encephalitis or encephalopathy caused by SFTS virus. Here, we report that SFTSV infection can active the NLRP3 inflammasome and induce IL-1β secretion in the brains of infected newborn mice. In infected human HMC3 microglia, SFTSV activated the NLRP3 inflammasome via the viral nonstructural protein NSs through interaction with its N-terminal fragment. Notably, our findings suggest that the activation of the NLRP3 inflammasome may promote SFTSV replication in infected microglial cells. This study may reveal a novel mechanism by SFTSV to dysregulate host responses through its nonstructural protein, which could help us understand viral neuropathogenesis in SFTS patients.
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Wang M, Tan W, Li J, Fang L, Yue M. The Endless Wars: Severe Fever With Thrombocytopenia Syndrome Virus, Host Immune and Genetic Factors. Front Cell Infect Microbiol 2022; 12:808098. [PMID: 35782112 PMCID: PMC9240209 DOI: 10.3389/fcimb.2022.808098] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 05/10/2022] [Indexed: 01/10/2023] Open
Abstract
Severe fever with thrombocytopenia syndrome (SFTS) is an emerging arboviral infectious disease with a high rate of lethality in susceptible humans and caused by severe fever with thrombocytopenia syndrome bunyavirus (SFTSV). Currently, neither vaccine nor specific antiviral drugs are available. In recent years, given the fact that both the number of SFTS cases and epidemic regions are increasing year by year, SFTS has become a public health problem. SFTSV can be internalized into host cells through the interaction between SFTSV glycoproteins and cell receptors and can activate the host immune system to trigger antiviral immune response. However, SFTSV has evolved multiple strategies to manipulate host factors to create an optimal environment for itself. Not to be discounted, host genetic factors may be operative also in the never-ending winning or losing wars. Therefore, the identifications of SFTSV, host immune and genetic factors, and their interactions are critical for understanding the pathogenic mechanisms of SFTSV infection. This review summarizes the updated pathogenesis of SFTS with regard to virus, host immune response, and host genetic factors to provide some novel perspectives of the prevention, treatment, as well as drug and vaccine developments.
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Affiliation(s)
- Min Wang
- Department of Infectious Diseases, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Weilong Tan
- Department of Infection Disease, Huadong Research Institute for Medicine and Biotechniques, Nanjing, China
| | - Jun Li
- Department of Infectious Diseases, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Liqun Fang
- State Key Lab Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- *Correspondence: Liqun Fang, ; Ming Yue,
| | - Ming Yue
- Department of Infectious Diseases, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
- *Correspondence: Liqun Fang, ; Ming Yue,
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Xu L, Li X, Gao X, Liu S, Pang Z, Wang Z. Viral suppression of type I interferon signaling by NSs proteins of DBV, SFSV and UUKV via NSs-mediated RIG-I degradation. BIOSAFETY AND HEALTH 2022. [DOI: 10.1016/j.bsheal.2022.05.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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14
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Reverse Genetics System for Heartland Bandavirus: NSs Protein Contributes to Heartland Bandavirus Virulence. J Virol 2022; 96:e0004922. [PMID: 35319224 DOI: 10.1128/jvi.00049-22] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Heartland bandavirus (HRTV), which is an emerging tick-borne virus first identified in Missouri in 2009, causes fever, fatigue, decreased appetite, headache, nausea, diarrhea, and muscle or joint pain in humans. HRTV is genetically close to Dabie bandavirus, which is the causative agent of severe fever with thrombocytopenia syndrome (SFTS) in humans and is known as SFTS virus (SFTSV). The generation of infectious HRTV entirely from cloned cDNAs has not yet been reported. The absence of a reverse genetics system for HRTV has delayed efforts to understand its pathogenesis and to generate vaccines and antiviral drugs. Here, we developed a reverse genetics system for HRTV, which employs an RNA polymerase I-mediated expression system. A recombinant nonstructural protein (NSs)-knockout HRTV (rHRTV-NSsKO) was generated. We found that NSs interrupted signaling associated with innate immunity in HRTV-infected cells. The rHRTV-NSsKO was highly attenuated, indicated by the apparent absence of symptoms in a mouse model of HRTV infection. Moreover, mice immunized with rHRTV-NSsKO survived a lethal dose of HRTV. These findings suggest that NSs is a virulence factor of HRTV and that rHRTV-NSsKO could be a vaccine candidate for HRTV. IMPORTANCE Heartland bandavirus (HRTV) is a tick-borne virus identified in the United States in 2009. HRTV causes fever, fatigue, decreased appetite, headache, nausea, diarrhea, and muscle or joint pain in humans. FDA-approved vaccines and antiviral drugs are unavailable. The lack of a reverse genetics system hampers efforts to develop such antiviral therapeutics. Here, we developed a reverse genetics system for HRTV that led to the generation of a recombinant nonstructural protein (NSs)-knockout HRTV (rHRTV-NSsKO). We found that NSs interrupted signaling associated with innate immunity in HRTV-infected cells. Furthermore, rHRTV-NSsKO was highly attenuated and immunogenic in a mouse model. These findings suggest that NSs is a virulence factor of HRTV and that rHRTV-NSsKO could be a vaccine candidate for HRTV.
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Single-cell landscape of peripheral immune responses to fatal SFTS. Cell Rep 2021; 37:110039. [PMID: 34818556 DOI: 10.1016/j.celrep.2021.110039] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Revised: 08/19/2021] [Accepted: 11/01/2021] [Indexed: 12/13/2022] Open
Abstract
Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease with high fatality. Poor prognosis of SFTS has been associated with dysregulated host immunity; however, the immune patterns associated with pathophysiology involving SFTS exacerbation remain unclear. Here, we show that the single-cell landscape of peripheral immune responses is reprogrammed in SFTS and characterized by monocyte shift to an intermediate type along with complement activation, perturbation of plasmablast composition, and highly exhausted T cells, all correlated with lethal consequences. We identify the overexpression of interferon (IFN)-stimulated genes across most immune cell types after SFTSV infection, which are simultaneously related to older age, high viremia, and a hyperinflammatory response. A retrospective clinical study reveals no efficiency of IFN-α in treating SFTS. These data collectively support the intermediate monocytes and IFN-I-inducible plasmablasts to be major targets for SFTS virus infection, and they indicate the pivotal role of the IFN-I response in exacerbating hyperinflammation and lethal SFTS.
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Kwon JS, Jin S, Kim JY, Ra SH, Kim T, Park SY, Kim MC, Park SY, Kim D, Cha HH, Lee HJ, Kim MJ, Chong YP, Lee SO, Choi SH, Kim YS, Lee KH, Kee SH, Kim SH. Viral and Immunologic Factors Associated with Fatal Outcome of Patients with Severe Fever with Thrombocytopenia Syndrome in Korea. Viruses 2021; 13:v13122351. [PMID: 34960620 PMCID: PMC8703577 DOI: 10.3390/v13122351] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/11/2021] [Accepted: 11/18/2021] [Indexed: 12/12/2022] Open
Abstract
Significant progress has been made on the molecular biology of the severe fever with thrombopenia virus (SFTSV); however, many parts of the pathophysiological mechanisms of mortality in SFTS remain unclear. In this study, we investigated virologic and immunologic factors for fatal outcomes of patients with SFTS. We prospectively enrolled SFTS patients admitted from July 2015 to October 2020. Plasma samples were subjected to SFTSV RNA RT-PCR, multiplex microbead immunoassay for 17 cytokines, and IFA assay. A total of 44 SFTS patients were enrolled, including 37 (84.1%) survivors and 7 (15.9%) non-survivors. Non-survivors had a 2.5 times higher plasma SFTSV load than survivors at admission (p < 0.001), and the viral load in non-survivors increased progressively during hospitalization. In addition, non-survivors did not develop adequate anti-SFTSV IgG, whereas survivors exhibited anti-SFTSV IgG during hospitalization. IFN-α, IL-10, IP-10, IFN-γ, IL-6, IL-8, MCP-1, MIP-1α, and G-CSF were significantly elevated in non-survivors compared to survivors and did not revert to normal ranges during hospitalization (p < 0.05). Severe signs of inflammation such as a high plasma concentration of IFN-α, IL-10, IP-10, IFN-γ, IL-6, IL-8, MCP-1, MIP-1α, and G-CSF, poor viral control, and inadequate antibody response during the disease course were associated with mortality in SFTS patients.
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Affiliation(s)
- Ji-Soo Kwon
- Department of Infectious Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea; (J.-S.K.); (S.J.); (J.-Y.K.); (S.-H.R.); (H.-H.C.); (H.-J.L.); (M.-J.K.); (Y.-P.C.); (S.-O.L.); (S.-H.C.); (Y.-S.K.)
| | - Sol Jin
- Department of Infectious Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea; (J.-S.K.); (S.J.); (J.-Y.K.); (S.-H.R.); (H.-H.C.); (H.-J.L.); (M.-J.K.); (Y.-P.C.); (S.-O.L.); (S.-H.C.); (Y.-S.K.)
| | - Ji-Yeun Kim
- Department of Infectious Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea; (J.-S.K.); (S.J.); (J.-Y.K.); (S.-H.R.); (H.-H.C.); (H.-J.L.); (M.-J.K.); (Y.-P.C.); (S.-O.L.); (S.-H.C.); (Y.-S.K.)
| | - Sang-Hyun Ra
- Department of Infectious Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea; (J.-S.K.); (S.J.); (J.-Y.K.); (S.-H.R.); (H.-H.C.); (H.-J.L.); (M.-J.K.); (Y.-P.C.); (S.-O.L.); (S.-H.C.); (Y.-S.K.)
| | - Taeeun Kim
- Division of Infectious Diseases, Gyeongsang National University Hospital, Gyeongsang National University School of Medicine, Jinju 52727, Korea;
| | - Se-Yoon Park
- Division of Infectious Diseases, Department of Internal Medicine, Soonchunhyang University Seoul Hospital, Soonchunhyang University College of Medicine, Seoul 04401, Korea;
| | - Min-Chul Kim
- Division of Infectious Diseases, Chung-Ang University Hospital, Seoul 06973, Korea;
| | - Seong-Yeon Park
- Department of Infectious Diseases, Dongguk University Ilsan Hospital, Goyang 10326, Korea;
| | - Dasarang Kim
- Department of Microbiology, Institute for Viral Diseases, College of Medicine, Korea University, Seoul 02841, Korea; (D.K.); (S.-H.K.)
| | - Hye-Hee Cha
- Department of Infectious Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea; (J.-S.K.); (S.J.); (J.-Y.K.); (S.-H.R.); (H.-H.C.); (H.-J.L.); (M.-J.K.); (Y.-P.C.); (S.-O.L.); (S.-H.C.); (Y.-S.K.)
| | - Hyun-Jung Lee
- Department of Infectious Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea; (J.-S.K.); (S.J.); (J.-Y.K.); (S.-H.R.); (H.-H.C.); (H.-J.L.); (M.-J.K.); (Y.-P.C.); (S.-O.L.); (S.-H.C.); (Y.-S.K.)
| | - Min-Jae Kim
- Department of Infectious Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea; (J.-S.K.); (S.J.); (J.-Y.K.); (S.-H.R.); (H.-H.C.); (H.-J.L.); (M.-J.K.); (Y.-P.C.); (S.-O.L.); (S.-H.C.); (Y.-S.K.)
| | - Yong-Pil Chong
- Department of Infectious Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea; (J.-S.K.); (S.J.); (J.-Y.K.); (S.-H.R.); (H.-H.C.); (H.-J.L.); (M.-J.K.); (Y.-P.C.); (S.-O.L.); (S.-H.C.); (Y.-S.K.)
| | - Sang-Oh Lee
- Department of Infectious Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea; (J.-S.K.); (S.J.); (J.-Y.K.); (S.-H.R.); (H.-H.C.); (H.-J.L.); (M.-J.K.); (Y.-P.C.); (S.-O.L.); (S.-H.C.); (Y.-S.K.)
| | - Sang-Ho Choi
- Department of Infectious Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea; (J.-S.K.); (S.J.); (J.-Y.K.); (S.-H.R.); (H.-H.C.); (H.-J.L.); (M.-J.K.); (Y.-P.C.); (S.-O.L.); (S.-H.C.); (Y.-S.K.)
| | - Yang-Soo Kim
- Department of Infectious Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea; (J.-S.K.); (S.J.); (J.-Y.K.); (S.-H.R.); (H.-H.C.); (H.-J.L.); (M.-J.K.); (Y.-P.C.); (S.-O.L.); (S.-H.C.); (Y.-S.K.)
| | - Keun-Hwa Lee
- Department of Microbiology, College of Medicine, Hanyang University, Seoul 04763, Korea;
| | - Sun-Ho Kee
- Department of Microbiology, Institute for Viral Diseases, College of Medicine, Korea University, Seoul 02841, Korea; (D.K.); (S.-H.K.)
| | - Sung-Han Kim
- Department of Infectious Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea; (J.-S.K.); (S.J.); (J.-Y.K.); (S.-H.R.); (H.-H.C.); (H.-J.L.); (M.-J.K.); (Y.-P.C.); (S.-O.L.); (S.-H.C.); (Y.-S.K.)
- Correspondence: ; Tel.: +82-2-3010-3305
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Wuerth JD, Weber F. NSs of the mildly virulent sandfly fever Sicilian virus is unable to inhibit interferon signaling and upregulation of interferon-stimulated genes. J Gen Virol 2021; 102. [PMID: 34726591 PMCID: PMC8742993 DOI: 10.1099/jgv.0.001676] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Phleboviruses (order Bunyavirales, family Phenuiviridae) are globally emerging arboviruses with a wide spectrum of virulence. Sandfly fever Sicilian virus (SFSV) is one of the most ubiquitous members of the genus Phlebovirus and associated with a self-limited, incapacitating febrile disease in travellers and military troops. The phleboviral NSs protein is an established virulence factor, acting as antagonist of the antiviral interferon (IFN) system. Consistently, we previously reported that SFSV NSs targets the induction of IFN mRNA synthesis by specifically binding to the DNA-binding domain of the IFN transcription factor IRF3. Here, we further characterized the effect of SFSV and its NSs towards IFN induction, and evaluated its potential to affect the downstream IFN-stimulated signalling and the subsequent transactivation of antiviral interferon-stimulated genes (ISGs). We found that SFSV dampened, but did not entirely abolish type I and type III IFN induction. Furthermore, SFSV NSs did not affect IFN signalling, resulting in substantial ISG expression in infected cells. Hence, although SFSV targets IRF3 to reduce IFN induction, it is not capable of entirely disarming the IFN system in the presence of high basal IRF3 and/or IRF7 levels, and we speculate that this significantly contributes to its low level of virulence.
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Affiliation(s)
- Jennifer Deborah Wuerth
- Institute for Virology, FB10-Veterinary Medicine, Justus-Liebig University, Giessen, Germany.,Institute of Innate Immunity, University of Bonn, Bonn, Germany
| | - Friedemann Weber
- Institute for Virology, FB10-Veterinary Medicine, Justus-Liebig University, Giessen, Germany
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Yan JM, Zhang WK, Li F, Zhou CM, Yu XJ. Integrated transcriptome profiling in THP-1 macrophages infected with bunyavirus SFTSV. Virus Res 2021; 306:198594. [PMID: 34637813 DOI: 10.1016/j.virusres.2021.198594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Revised: 09/10/2021] [Accepted: 10/06/2021] [Indexed: 10/20/2022]
Abstract
Severe fever with thrombocytopenia syndrome virus (SFTSV) is a tick-borne bunyavirus that causes an emerging hemorrhagic fever termed SFTS with high mortality. However, knowledge of SFTSV-host interactions is largely limited. Here, we performed a global transcriptome analysis of mRNAs and lncRNAs in THP-1 macrophages infected with SFTSV for 24 and 48 h. A total of 2,334 differentially expressed mRNAs and 154 differentially expressed lncRNAs were identified with 577 mRNAs and 31 lncRNAs commonly changed at both time points. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that differentially expressed mRNAs were mainly associated with innate immune, cytokine signaling, systemic lupus erythematosus, and alcoholism. Differentially expressed lncRNAs were enriched in systemic lupus erythematosus, alcoholism, and ribosome. Bioinformatic analysis also revealed hub regulatory mRNAs including IL6, TNF, UBA52, SRC, IL10, CXCL10, and CDK1 and core regulatory lncRNAs including XLOC_083027 and XLOC_113317. Transcription factor analysis of the differentially expressed mRNAs revealed that IRF1, SPI1, SPIB, ELF5, and FEV were enriched during SFTSV infection. Taken together, our studies illustrate the complex interaction between THP-1 macrophages and SFTSV.
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Affiliation(s)
- Jia-Min Yan
- State Key Laboratory of Virology, School of Health Sciences, Wuhan University, Wuhan, 430071, China
| | - Wen-Kang Zhang
- State Key Laboratory of Virology, School of Health Sciences, Wuhan University, Wuhan, 430071, China
| | - Fei Li
- School of Public Health, Shandong University, Jinan, Shandong 250012, China
| | - Chuan-Min Zhou
- State Key Laboratory of Virology, School of Health Sciences, Wuhan University, Wuhan, 430071, China; Zhongnan hospital of Wuhan University, Wuhan, 430071, China.
| | - Xue-Jie Yu
- State Key Laboratory of Virology, School of Health Sciences, Wuhan University, Wuhan, 430071, China.
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Suppression of JAK-STAT signaling by Epstein-Barr virus tegument protein BGLF2 through recruitment of SHP1 phosphatase and promotion of STAT2 degradation. J Virol 2021; 95:e0102721. [PMID: 34319780 DOI: 10.1128/jvi.01027-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Some lytic proteins encoded by Epstein-Barr virus (EBV) suppress host interferon (IFN) signaling to facilitate viral replication. In this study we sought to identify and characterize EBV proteins antagonizing IFN signaling. The induction of IFN-stimulated genes (ISGs) by IFN-β was effectively suppressed by EBV. A functional screen was therefore performed to identify IFN-antagonizing proteins encoded by EBV. EBV tegument protein BGLF2 was identified as a potent suppressor of JAK-STAT signaling. This activity was found to be independent of its stimulatory effect on p38 and JNK pathways. Association of BGLF2 with STAT2 resulted in more pronounced K48-linked polyubiquitination and proteasomal degradation of the latter. Mechanistically, BGLF2 promoted the recruitment of SHP1 phosphatase to STAT1 to inhibit its tyrosine phosphorylation. In addition, BGLF2 associated with cullin 1 E3 ubiquitin ligase to facilitate its recruitment to STAT2. Consequently, BGLF2 suppressed ISG induction by IFN-β. Furthermore, BGLF2 also suppressed type II and type III IFN signaling, although the suppressive effect on type II IFN response was milder. When pre-treated with IFN-β, host cells became less susceptible to primary infection of EBV. This phenotype was reversed when expression of BGLF2 was enforced. Finally, genetic disruption of BGLF2 in EBV led to more pronounced induction of ISGs. Taken together, our study unveils the roles of BGLF2 not only in the subversion of innate IFN response but also in lytic infection and reactivation of EBV. Importance Epstein-Barr virus (EBV) is an oncogenic virus associated with the development of lymphoid and epithelial malignancies. EBV has to subvert interferon-mediated host antiviral response to replicate and cause diseases. It is therefore of great interest to identify and characterize interferon-antagonizing proteins produced by EBV. In this study we perform a screen to search for EBV proteins that suppress the action of interferons. We further show that BGLF2 protein of EBV is particularly strong in this suppression. This is achieved by inhibiting two key proteins STAT1 and STAT2 that mediate the antiviral activity of interferons. BGLF2 recruits a host enzyme to remove the phosphate group from STAT1 thereby inactivating its activity. BGLF2 also redirects STAT2 for degradation. A recombinant virus in which BGLF2 gene has been disrupted can activate host interferon response more robustly. Our findings reveal a novel mechanism by which EBV BGLF2 protein suppresses interferon signaling.
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20
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Zhang L, Fu Y, Zhang R, Guan Y, Jiang N, Zheng N, Wu Z. Nonstructural Protein NSs Hampers Cellular Antiviral Response through LSm14A during Severe Fever with Thrombocytopenia Syndrome Virus Infection. THE JOURNAL OF IMMUNOLOGY 2021; 207:590-601. [PMID: 34244294 DOI: 10.4049/jimmunol.2100148] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 05/10/2021] [Indexed: 11/19/2022]
Abstract
The nonstructural protein (NSs) of severe fever with thrombocytopenia syndrome virus (SFTSV) plays multiple functions in the virus life cycle. Proteomic screening for host proteins interacting with NSs identified the cellular protein LSm14A. LSm14A, a member of the LSm family involved in RNA processing in the processing bodies, binds to viral RNA or synthetic homolog and mediates IFN regulatory factor 3 activation and IFN-β induction. NSs interacted with and colocalized with LSm14A, and this interaction effectively inhibited downstream phosphorylation and dimerization of IFN regulatory factor 3, resulting in the suppression of antiviral signaling and IFN induction in several cell types of human origin. Knockdown of NSs resulted in the suppression of SFTSV replication in host cells. Viral RNA bound to LSm14A-NSs protein complex during the interaction. A newly discovered LRRD motif of NSs functioned to interact with LSm14A. Altogether, our data demonstrated a mechanism used by SFTSV to inhibit host innate immune response.
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Affiliation(s)
- Li Zhang
- Center for Public Health Research, Medical School, Nanjing University, Nanjing, People's Republic of China
| | - Yuxuan Fu
- Center for Public Health Research, Medical School, Nanjing University, Nanjing, People's Republic of China
| | - Rui Zhang
- Center for Public Health Research, Medical School, Nanjing University, Nanjing, People's Republic of China
| | - Yajie Guan
- Center for Public Health Research, Medical School, Nanjing University, Nanjing, People's Republic of China
| | - Na Jiang
- Center for Public Health Research, Medical School, Nanjing University, Nanjing, People's Republic of China
| | - Nan Zheng
- Center for Public Health Research, Medical School, Nanjing University, Nanjing, People's Republic of China; .,State Key Lab of Analytical Chemistry for Life Science, Nanjing University, Nanjing, People's Republic of China; and.,Medical School and Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, People's Republic of China
| | - Zhiwei Wu
- Center for Public Health Research, Medical School, Nanjing University, Nanjing, People's Republic of China; .,State Key Lab of Analytical Chemistry for Life Science, Nanjing University, Nanjing, People's Republic of China; and.,Medical School and Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, People's Republic of China
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21
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Zhou CM, Yu XJ. Unraveling the Underlying Interaction Mechanism Between Dabie bandavirus and Innate Immune Response. Front Immunol 2021; 12:676861. [PMID: 34122440 PMCID: PMC8190332 DOI: 10.3389/fimmu.2021.676861] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Accepted: 05/10/2021] [Indexed: 12/22/2022] Open
Abstract
The genus Bandavirus consists of seven tick-borne bunyaviruses, among which four are known to infect humans. Dabie bandavirus, severe fever with thrombocytopenia syndrome virus (SFTSV), poses serious threats to public health worldwide. SFTSV is a tick-borne virus mainly reported in China, South Korea, and Japan with a mortality rate of up to 30%. To date, most immunology-related studies focused on the antagonistic role of SFTSV non-structural protein (NSs) in sequestering RIG-I-like-receptors (RLRs)-mediated type I interferon (IFN) induction and type I IFN mediated signaling pathway. It is still elusive whether the interaction of SFTSV and other conserved innate immune responses exists. As of now, no specific vaccines or therapeutics are approved for SFTSV prevention or treatments respectively, in part due to a lack of comprehensive understanding of the molecular interactions occurring between SFTSV and hosts. Hence, it is necessary to fully understand the host-virus interactions including antiviral responses and viral evasion mechanisms. In this review, we highlight the recent progress in understanding the pathogenesis of SFTS and speculate underlying novel mechanisms in response to SFTSV infection.
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Affiliation(s)
- Chuan-min Zhou
- State Key Laboratory of Virology, School of Health Sciences, Wuhan University, Wuhan, China
- Department of Infectious Diseases, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Xue-jie Yu
- State Key Laboratory of Virology, School of Health Sciences, Wuhan University, Wuhan, China
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22
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Preparation of a polyclonal antibody against the non-structural protein, NSs of SFTSV. Protein Expr Purif 2021; 184:105892. [PMID: 33895264 DOI: 10.1016/j.pep.2021.105892] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 04/18/2021] [Accepted: 04/19/2021] [Indexed: 11/23/2022]
Abstract
Severe fever with thrombocytopenia syndrome virus (SFTSV) is newly discovered virus which is the member of the order Bunyavirales, family phenuiviridae, phlebovirus genus. Its genome is composed of 3 segments of negative-sense RNA L, M and S. NSs is a non structure protein encoded by S segment which is important for viral replication and virulence. NSs protein of SFTSV is only involved in the regulation of host innate immune responses and suppression of IFN-promoter activities. So, the exact functions of this protein need to be studied deeply. To understand the exact role of NSs from SFTSV in viral replication and host immune response, a qualified antibody against this protein is required. In this study, NSs gene of SFTSV, was cloned into a bacterial expression vector (pGEX-6P-1) and the recombinant plasmid was transformed into Escherichia coli BL21 (DE3) cells. The SFTSV NSs fusion protein was purified using Glutathione Sepharose 4B and utilized as an antigen to immunize rabbits and obtain an anti-SFTSV NSs polyclonal antibody. Proper expression of the fusion protein and polyclonal antibody specificity were confirmed by western blotting and immunofluorescence analyses. The polyclonal antibody recognized NSs from SFTSV specifically. This is the first report that NSs can form viroplasm-like structures not only in infected cells but also in transfected cells with NSs plasmids. This polyclonal antibody will be useful for future studies of NSs functions.
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Lee JK, Shin OS. Nonstructural Protein of Severe Fever with Thrombocytopenia Syndrome Phlebovirus Inhibits TBK1 to Evade Interferon-Mediated Response. J Microbiol Biotechnol 2021; 31:226-232. [PMID: 33397830 PMCID: PMC9705905 DOI: 10.4014/jmb.2008.08048] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 12/10/2020] [Accepted: 12/28/2020] [Indexed: 12/15/2022]
Abstract
Severe fever with thrombocytopenia syndrome virus (SFTSV) is an emerging phlebovirus of the Phenuiviridae family that has been circulating in the following Asian countries: Vietnam, Myanmar, Taiwan, China, Japan, and South Korea. Despite the increasing infection rates and relatively high mortality rate, there is limited information available regarding SFTSV pathogenesis. In addition, there are currently no vaccines or effective antiviral treatments available. Previous reports have shown that SFTSV suppresses the host immune response and its nonstructural proteins (NSs) function as an antagonist of type I interferon (IFN), whose induction is an essential part of the host defense system against viral infections. Given that SFTSV NSs suppress the innate immune response by inhibiting type I IFN, we investigated the mechanism utilized by SFTSV NSs to evade IFN-mediated response. Our co-immunoprecipitation data suggest the interactions between NSs and retinoic acid inducible gene-I (RIG-I) or TANK binding kinase 1 (TBK1). Furthermore, confocal analysis indicates the ability of NSs to sequester RIG-I and related downstream molecules in the cytoplasmic structures called inclusion bodies (IBs). NSs are also capable of inhibiting TBK1-interferon regulatory factor 3 (IRF3) interaction, and therefore prevent the phosphorylation and nuclear translocation of IRF3 for the induction of type I IFN. The ability of SFTSV NSs to interact with and sequester TBK1 and IRF3 in IBs demonstrate an effective yet unique method utilized by SFTSV to evade and suppress host immunity.
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Affiliation(s)
- Jae Kyung Lee
- BK21 Graduate program, Department of Biomedical Sciences, Korea University College of Medicine, Seoul 08308, Republic of Korea
| | - Ok Sarah Shin
- BK21 Graduate program, Department of Biomedical Sciences, Korea University College of Medicine, Seoul 08308, Republic of Korea,Corresponding author Phone: +82-2-2626-3280 E-mail:
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Liu JW, Chu M, Jiao YJ, Zhou CM, Qi R, Yu XJ. SFTSV Infection Induced Interleukin-1β Secretion Through NLRP3 Inflammasome Activation. Front Immunol 2021; 12:595140. [PMID: 33708197 PMCID: PMC7940371 DOI: 10.3389/fimmu.2021.595140] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 01/11/2021] [Indexed: 11/13/2022] Open
Abstract
Severe fever with thrombocytopenia syndrome virus (SFTSV) is an emerging tick-borne virus that causes hemorrhagic fever. Previous studies showed that SFTSV-infected patients exhibited elevated levels of pro-inflammatory cytokines like interleukin-1β (IL-1β), indicating that SFTSV infection may activate inflammasomes. However, the detailed mechanism remains poorly understood. Herein, we found that SFTSV could stimulate the IL-1β secretion in the infected human peripheral blood mononuclear cells (PBMCs), human macrophages, and C57/BL6 mice. We demonstrate that the maturation and secretion of IL-1β during SFTSV infection is mediated by the nucleotide and oligomerization domain, leucine-rich repeat-containing protein family, pyrin-containing domain 3 (NLRP3) inflammasome. This process is dependent on protease caspase-1, a component of the NLRP3 inflammasome complex. For the first time, our study discovered the role of NLRP3 in response to SFTSV infection. This finding may lead to the development of novel drugs to impede the pathogenesis of SFTSV infection.
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Affiliation(s)
- Jian-Wei Liu
- State Key Laboratory of Virology, School of Health Sciences, Wuhan University, Wuhan, China
| | - Min Chu
- State Key Laboratory of Virology, School of Health Sciences, Wuhan University, Wuhan, China
| | - Yong-Jun Jiao
- Institute of Pathogenic Microbiology, Jiangsu Provincial Center for Disease Prevention and Control, Nanjing, China
| | - Chuan-Min Zhou
- State Key Laboratory of Virology, School of Health Sciences, Wuhan University, Wuhan, China
| | - Rui Qi
- State Key Laboratory of Virology, School of Health Sciences, Wuhan University, Wuhan, China
| | - Xue-Jie Yu
- State Key Laboratory of Virology, School of Health Sciences, Wuhan University, Wuhan, China
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A Look into Bunyavirales Genomes: Functions of Non-Structural (NS) Proteins. Viruses 2021; 13:v13020314. [PMID: 33670641 PMCID: PMC7922539 DOI: 10.3390/v13020314] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/12/2021] [Accepted: 02/16/2021] [Indexed: 12/13/2022] Open
Abstract
In 2016, the Bunyavirales order was established by the International Committee on Taxonomy of Viruses (ICTV) to incorporate the increasing number of related viruses across 13 viral families. While diverse, four of the families (Peribunyaviridae, Nairoviridae, Hantaviridae, and Phenuiviridae) contain known human pathogens and share a similar tri-segmented, negative-sense RNA genomic organization. In addition to the nucleoprotein and envelope glycoproteins encoded by the small and medium segments, respectively, many of the viruses in these families also encode for non-structural (NS) NSs and NSm proteins. The NSs of Phenuiviridae is the most extensively studied as a host interferon antagonist, functioning through a variety of mechanisms seen throughout the other three families. In addition, functions impacting cellular apoptosis, chromatin organization, and transcriptional activities, to name a few, are possessed by NSs across the families. Peribunyaviridae, Nairoviridae, and Phenuiviridae also encode an NSm, although less extensively studied than NSs, that has roles in antagonizing immune responses, promoting viral assembly and infectivity, and even maintenance of infection in host mosquito vectors. Overall, the similar and divergent roles of NS proteins of these human pathogenic Bunyavirales are of particular interest in understanding disease progression, viral pathogenesis, and developing strategies for interventions and treatments.
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Molecular Signatures of Inflammatory Profile and B-Cell Function in Patients with Severe Fever with Thrombocytopenia Syndrome. mBio 2021; 12:mBio.02583-20. [PMID: 33593977 PMCID: PMC8545090 DOI: 10.1128/mbio.02583-20] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Dabie bandavirus (severe fever with thrombocytopenia syndrome virus [SFTSV]) induces an immunopathogenic disease with a high fatality rate; however, the mechanisms underlying its clinical manifestations are largely unknown. In this study, we applied targeted proteomics and single-cell transcriptomics to examine the differential immune landscape in SFTS patient blood. Serum immunoprofiling identified low-risk and high-risk clusters of SFTS patients based on inflammatory cytokine levels, which corresponded to disease severity. Single-cell transcriptomic analysis of SFTS patient peripheral blood mononuclear cells (PBMCs) at different infection stages showed pronounced expansion of B cells with alterations in B-cell subsets in fatal cases. Furthermore, plasma cells in which the interferon (IFN) pathway is downregulated were identified as the primary reservoir of SFTSV replication. This study identified not only the molecular signatures of serum inflammatory cytokines and B-cell lineage populations in SFTSV-induced fatalities but also plasma cells as the viral reservoir. Thus, this suggests that altered B-cell function is linked to lethality in SFTSV infections.
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Gallo G, Caignard G, Badonnel K, Chevreux G, Terrier S, Szemiel A, Roman-Sosa G, Binder F, Gu Q, Da Silva Filipe A, Ulrich RG, Kohl A, Vitour D, Tordo N, Ermonval M. Interactions of Viral Proteins from Pathogenic and Low or Non-Pathogenic Orthohantaviruses with Human Type I Interferon Signaling. Viruses 2021; 13:140. [PMID: 33478127 PMCID: PMC7835746 DOI: 10.3390/v13010140] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 01/12/2021] [Accepted: 01/16/2021] [Indexed: 12/13/2022] Open
Abstract
Rodent-borne orthohantaviruses are asymptomatic in their natural reservoir, but they can cause severe diseases in humans. Although an exacerbated immune response relates to hantaviral pathologies, orthohantaviruses have to antagonize the antiviral interferon (IFN) response to successfully propagate in infected cells. We studied interactions of structural and nonstructural (NSs) proteins of pathogenic Puumala (PUUV), low-pathogenic Tula (TULV), and non-pathogenic Prospect Hill (PHV) viruses, with human type I and III IFN (IFN-I and IFN-III) pathways. The NSs proteins of all three viruses inhibited the RIG-I-activated IFNβ promoter, while only the glycoprotein precursor (GPC) of PUUV, or its cleavage product Gn/Gc, and the nucleocapsid (N) of TULV inhibited it. Moreover, the GPC of both PUUV and TULV antagonized the promoter of IFN-stimulated responsive elements (ISRE). Different viral proteins could thus contribute to inhibition of IFNβ response in a viral context. While PUUV and TULV strains replicated similarly, whether expressing entire or truncated NSs proteins, only PUUV encoding a wild type NSs protein led to late IFN expression and activation of IFN-stimulated genes (ISG). This, together with the identification of particular domains of NSs proteins and different biological processes that are associated with cellular proteins in complex with NSs proteins, suggested that the activation of IFN-I is probably not the only antiviral pathway to be counteracted by orthohantaviruses and that NSs proteins could have multiple inhibitory functions.
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Affiliation(s)
- Giulia Gallo
- Unité des Stratégies Antivirales, Institut Pasteur, 75015 Paris, France; (G.G.); (N.T.)
- Ecole Doctorale Complexité du Vivant, Sorbonne Université, 75006 Paris, France
| | - Grégory Caignard
- UMR 1161 Virologie, Anses-INRAE-EnvA, 94700 Maisons-Alfort, France; (G.C.); (D.V.)
| | - Karine Badonnel
- BREED, INRAE, Université Paris-Saclay, 78350 Jouy-en-Josas, France;
| | - Guillaume Chevreux
- Institut Jacques Monod, CNRS UMR 7592, ProteoSeine Mass Spectrometry Plateform, Université de Paris, 75013 Paris, France; (G.C.); (S.T.)
| | - Samuel Terrier
- Institut Jacques Monod, CNRS UMR 7592, ProteoSeine Mass Spectrometry Plateform, Université de Paris, 75013 Paris, France; (G.C.); (S.T.)
| | - Agnieszka Szemiel
- MRC-University of Glasgow Centre for Virus Research, Glasgow G61 1QH, UK; (A.S.); (Q.G.); (A.D.S.F.); (A.K.)
| | | | - Florian Binder
- Friedrich-Loeffler-Institut, Institute of Novel and Emerging Infectious Diseases, 17493 Greifswald-Insel Riems, Germany; (F.B.); (R.G.U.)
| | - Quan Gu
- MRC-University of Glasgow Centre for Virus Research, Glasgow G61 1QH, UK; (A.S.); (Q.G.); (A.D.S.F.); (A.K.)
| | - Ana Da Silva Filipe
- MRC-University of Glasgow Centre for Virus Research, Glasgow G61 1QH, UK; (A.S.); (Q.G.); (A.D.S.F.); (A.K.)
| | - Rainer G. Ulrich
- Friedrich-Loeffler-Institut, Institute of Novel and Emerging Infectious Diseases, 17493 Greifswald-Insel Riems, Germany; (F.B.); (R.G.U.)
| | - Alain Kohl
- MRC-University of Glasgow Centre for Virus Research, Glasgow G61 1QH, UK; (A.S.); (Q.G.); (A.D.S.F.); (A.K.)
| | - Damien Vitour
- UMR 1161 Virologie, Anses-INRAE-EnvA, 94700 Maisons-Alfort, France; (G.C.); (D.V.)
| | - Noël Tordo
- Unité des Stratégies Antivirales, Institut Pasteur, 75015 Paris, France; (G.G.); (N.T.)
- Institut Pasteur de Guinée, BP 4416 Conakry, Guinea
| | - Myriam Ermonval
- Unité des Stratégies Antivirales, Institut Pasteur, 75015 Paris, France; (G.G.); (N.T.)
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28
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Baseline mapping of severe fever with thrombocytopenia syndrome virology, epidemiology and vaccine research and development. NPJ Vaccines 2020; 5:111. [PMID: 33335100 PMCID: PMC7746727 DOI: 10.1038/s41541-020-00257-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 10/13/2020] [Indexed: 12/13/2022] Open
Abstract
Severe fever with thrombocytopenia syndrome virus (SFTSV) is a newly emergent tick-borne bunyavirus first discovered in 2009 in China. SFTSV is a growing public health problem that may become more prominent owing to multiple competent tick-vectors and the expansion of human populations in areas where the vectors are found. Although tick-vectors of SFTSV are found in a wide geographic area, SFTS cases have only been reported from China, South Korea, Vietnam, and Japan. Patients with SFTS often present with high fever, leukopenia, and thrombocytopenia, and in some cases, symptoms can progress to severe outcomes, including hemorrhagic disease. Reported SFTSV case fatality rates range from ~5 to >30% depending on the region surveyed, with more severe disease reported in older individuals. Currently, treatment options for this viral infection remain mostly supportive as there are no licensed vaccines available and research is in the discovery stage. Animal models for SFTSV appear to recapitulate many facets of human disease, although none of the models mirror all clinical manifestations. There are insufficient data available on basic immunologic responses, the immune correlate(s) of protection, and the determinants of severe disease by SFTSV and related viruses. Many aspects of SFTSV virology and epidemiology are not fully understood, including a detailed understanding of the annual numbers of cases and the vertebrate host of the virus, so additional research on this disease is essential towards the development of vaccines and therapeutics.
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29
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Li J, Li S, Yang L, Cao P, Lu J. Severe fever with thrombocytopenia syndrome virus: a highly lethal bunyavirus. Crit Rev Microbiol 2020; 47:112-125. [PMID: 33245676 DOI: 10.1080/1040841x.2020.1847037] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Severe fever with thrombocytopenia syndrome virus (SFTSV) is a novel bunyavirus. Since 2007, SFTS disease has been reported in China with high fatality rate up to 30%, which drew high attention from Centre for Disease Control and Prevention and government. SFTSV is endemic in the centra l and eastern China, Korea and Japan. There also have been similar cases reported in Vietnam. The number of SFTSV infection cases has a steady growth in these years. As SFTSV could transmitted from person to person, it will expose the public to infectious risk. In 2018 annual review of the Blueprint list of priority diseases, World Health Organisation has listed SFTSV infection as prioritised diseases for research and development in emergency contexts. However, the pathogenesis of SFTSV remains largely unclear. Currently, there are no specific therapeutics or vaccines to combat infections of SFTSV. This review discusses recent findings of epidemiology, transmission pathway, pathogenesis and treatments of SFTS disease.
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Affiliation(s)
- Jing Li
- NHC Key Laboratory of Carcinogenesis, Department of Hematology, Xiangya Hospital, Central South University, Changsha, China.,Department of Microbiology, School of Basic Medical Sciences, Central South University, Changsha, China.,China-Africa Research Center of Infectious Diseases, Central South University, Changsha, China
| | - Shen Li
- NHC Key Laboratory of Carcinogenesis, Department of Hematology, Xiangya Hospital, Central South University, Changsha, China.,Department of Microbiology, School of Basic Medical Sciences, Central South University, Changsha, China.,China-Africa Research Center of Infectious Diseases, Central South University, Changsha, China
| | - Li Yang
- NHC Key Laboratory of Carcinogenesis, Department of Hematology, Xiangya Hospital, Central South University, Changsha, China.,Department of Microbiology, School of Basic Medical Sciences, Central South University, Changsha, China.,China-Africa Research Center of Infectious Diseases, Central South University, Changsha, China
| | - Pengfei Cao
- NHC Key Laboratory of Carcinogenesis, Department of Hematology, Xiangya Hospital, Central South University, Changsha, China.,Department of Microbiology, School of Basic Medical Sciences, Central South University, Changsha, China.,China-Africa Research Center of Infectious Diseases, Central South University, Changsha, China
| | - Jianhong Lu
- NHC Key Laboratory of Carcinogenesis, Department of Hematology, Xiangya Hospital, Central South University, Changsha, China.,Department of Microbiology, School of Basic Medical Sciences, Central South University, Changsha, China.,China-Africa Research Center of Infectious Diseases, Central South University, Changsha, China
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30
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Wang L, Kaya KD, Kim S, Brooks MJ, Wang J, Xin Y, Qian J, Swaroop A, Handa JT. Retinal pigment epithelium transcriptome analysis in chronic smoking reveals a suppressed innate immune response and activation of differentiation pathways. Free Radic Biol Med 2020; 156:176-189. [PMID: 32634473 PMCID: PMC7434665 DOI: 10.1016/j.freeradbiomed.2020.06.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 05/26/2020] [Accepted: 06/03/2020] [Indexed: 02/06/2023]
Abstract
Cigarette smoking, a powerful mixture of chemical oxidants, is the strongest environmental risk factor for developing age-related macular degeneration (AMD), the most common cause of blindness among the elderly in western societies. Despite intensive study, the full impact of smoking on the retinal pigment epithelium (RPE), a central cell type involved in AMD pathobiology, remains unknown. The relative contribution of the known dysfunctional pathways to AMD, at what stage they are most pathogenic, or whether other processes are relevant, is poorly understood, and furthermore, whether smoking activates them, is unknown. We performed global RNA-sequencing of the RPE from C57BL/6J mice exposed to chronic cigarette smoke for 6 months to identify potential pathogenic and cytoprotective pathways. The RPE transcriptome induced by chronic cigarette smoking exhibited a mixed response of marked suppression of the innate immune response including type I and II interferons and upregulation of cell differentiation and morphogenic gene clusters, suggesting an attempt by the RPE to maintain its differentiated state despite smoke-induced injury. Given that mice exposed to chronic smoke develop early features of AMD, these novel findings are potentially relevant to the transition from aging to AMD.
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Affiliation(s)
- Lei Wang
- Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA.
| | - Koray D Kaya
- Neurobiology, Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
| | - Sujung Kim
- Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA.
| | - Matthew J Brooks
- Neurobiology, Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
| | - Jie Wang
- Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA.
| | - Ying Xin
- Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA.
| | - Jiang Qian
- Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA.
| | - Anand Swaroop
- Neurobiology, Neurodegeneration & Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
| | - James T Handa
- Wilmer Eye Institute, Johns Hopkins University, Baltimore, MD, USA.
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31
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Wong LYR, Ye ZW, Lui PY, Zheng X, Yuan S, Zhu L, Fung SY, Yuen KS, Siu KL, Yeung ML, Cai Z, Woo PCY, Yuen KY, Chan CP, Jin DY. Middle East Respiratory Syndrome Coronavirus ORF8b Accessory Protein Suppresses Type I IFN Expression by Impeding HSP70-Dependent Activation of IRF3 Kinase IKKε. THE JOURNAL OF IMMUNOLOGY 2020; 205:1564-1579. [PMID: 32747502 DOI: 10.4049/jimmunol.1901489] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 07/08/2020] [Indexed: 12/11/2022]
Abstract
Middle East respiratory syndrome coronavirus (MERS-CoV) is a highly pathogenic human coronavirus causing severe disease and mortality. MERS-CoV infection failed to elicit robust IFN response, suggesting that the virus might have evolved strategies to evade host innate immune surveillance. In this study, we identified and characterized type I IFN antagonism of MERS-CoV open reading frame (ORF) 8b accessory protein. ORF8b was abundantly expressed in MERS-CoV-infected Huh-7 cells. When ectopically expressed, ORF8b inhibited IRF3-mediated IFN-β expression induced by Sendai virus and poly(I:C). ORF8b was found to act at a step upstream of IRF3 to impede the interaction between IRF3 kinase IKKε and chaperone protein HSP70, which is required for the activation of IKKε and IRF3. An infection study using recombinant wild-type and ORF8b-deficient MERS-CoV further confirmed the suppressive role of ORF8b in type I IFN induction and its disruption of the colocalization of HSP70 with IKKε. Ectopic expression of HSP70 relieved suppression of IFN-β expression by ORF8b in an IKKε-dependent manner. Enhancement of IFN-β induction in cells infected with ORF8b-deficient virus was erased when HSP70 was depleted. Taken together, HSP70 chaperone is important for IKKε activation, and MERS-CoV ORF8b suppresses type I IFN expression by competing with IKKε for interaction with HSP70.
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Affiliation(s)
- Lok-Yin Roy Wong
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong
| | - Zi-Wei Ye
- State Key Laboratory of Emerging Infectious Diseases, Department of Microbiology, The University of Hong Kong, Pokfulam, Hong Kong; and
| | - Pak-Yin Lui
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong
| | - Xuyang Zheng
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong
| | - Shuofeng Yuan
- State Key Laboratory of Emerging Infectious Diseases, Department of Microbiology, The University of Hong Kong, Pokfulam, Hong Kong; and
| | - Lin Zhu
- State Key Laboratory of Environmental and Biological Analysis, Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong
| | - Sin-Yee Fung
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong
| | - Kit-San Yuen
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong
| | - Kam-Leung Siu
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong
| | - Man-Lung Yeung
- State Key Laboratory of Emerging Infectious Diseases, Department of Microbiology, The University of Hong Kong, Pokfulam, Hong Kong; and
| | - Zongwei Cai
- State Key Laboratory of Environmental and Biological Analysis, Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong
| | - Patrick Chiu-Yat Woo
- State Key Laboratory of Emerging Infectious Diseases, Department of Microbiology, The University of Hong Kong, Pokfulam, Hong Kong; and
| | - Kwok-Yung Yuen
- State Key Laboratory of Emerging Infectious Diseases, Department of Microbiology, The University of Hong Kong, Pokfulam, Hong Kong; and
| | - Chi-Ping Chan
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong;
| | - Dong-Yan Jin
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong;
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The Severe Fever with Thrombocytopenia Syndrome Virus NSs Protein Interacts with CDK1 To Induce G 2 Cell Cycle Arrest and Positively Regulate Viral Replication. J Virol 2020; 94:JVI.01575-19. [PMID: 31852787 DOI: 10.1128/jvi.01575-19] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 12/10/2019] [Indexed: 12/12/2022] Open
Abstract
Severe fever with thrombocytopenia syndrome virus (SFTSV) is a newly identified phlebovirus associated with severe hemorrhagic fever in humans. While many viruses subvert the host cell cycle to promote viral growth, it is unknown whether this is a strategy employed by SFTSV. In this study, we investigated how SFTSV manipulates the cell cycle and the effect of the host cell cycle on SFTSV replication. Our results suggest that cells arrest at the G2/M transition following infection with SFTSV. The accumulation of cells at the G2/M transition did not affect virus adsorption and entry but did facilitate viral replication. In addition, we found that SFTSV NSs, a nonstructural protein that forms viroplasm-like structures in the cytoplasm of infected cells and promotes virulence by modulating the interferon response, induces a large number of cells to arrest at the G2/M transition by interacting with CDK1. The interaction between NSs and CDK1, which is inclusion body dependent, inhibits formation and nuclear import of the cyclin B1-CDK1 complex, thereby leading to cell cycle arrest. Expression of a CDK1 loss-of-function mutant reversed the inhibitive effect of NSs on the cell cycle, suggesting that this protein is a potential antiviral target. Our study provides new insight into the role of a specific viral protein in SFTSV replication, indicating that NSs induces G2/M arrest of SFTSV-infected cells, which promotes viral replication.IMPORTANCE Severe fever with thrombocytopenia syndrome virus (SFTSV) is a tick-borne pathogen that causes severe hemorrhagic fever. Although SFTSV poses a serious threat to public health and was recently isolated, its pathogenesis remains unclear. In particular, the relationship between SFTSV infection and the host cell cycle has not been described. Here, we show for the first time that both asynchronized and synchronized SFTSV-susceptible cells arrest at the G2/M checkpoint following SFTSV infection and that the accumulation of cells at this checkpoint facilitates viral replication. We also identify a key mechanism underlying SFTSV-induced G2/M arrest, in which SFTSV NSs interacts with CDK1 to inhibit formation and nuclear import of the cyclin B1-CDK1 complex, thus preventing it from regulating cell cycle progression. Our study highlights the key role that NSs plays in SFTSV-induced G2/M arrest.
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Clarke EC, Bradfute SB. The use of mice lacking type I or both type I and type II interferon responses in research on hemorrhagic fever viruses. Part 1: Potential effects on adaptive immunity and response to vaccination. Antiviral Res 2020; 174:104703. [DOI: 10.1016/j.antiviral.2019.104703] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 12/10/2019] [Accepted: 12/20/2019] [Indexed: 12/25/2022]
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Cross-genotype protection of live-attenuated vaccine candidate for severe fever with thrombocytopenia syndrome virus in a ferret model. Proc Natl Acad Sci U S A 2019; 116:26900-26908. [PMID: 31818942 PMCID: PMC6936527 DOI: 10.1073/pnas.1914704116] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Severe fever with thrombocytopenia syndrome virus (SFTSV) is an emerging viral pathogen discovered in 2009. The virus is present in countries of East Asia and is transmitted through the bite of an infected Haemaphysalis longicornis tick. SFTSV disease is associated with high morbidity and is often fatal. Despite the incidence of disease, no antiviral therapy or vaccine has been approved for use. Here, we report and assess 2 live attenuated viruses as vaccine candidates in our recently described ferret model of infection. We show that the viruses caused no clinical disease or mortality in healthy animals. Immunized animals mounted a robust humoral immune response to a single dose of virus, and this response protected the animals from a lethal challenge. Severe fever with thrombocytopenia syndrome (SFTS) virus (SFTSV) is an emerging tick-borne virus classified within the Banyangvirus genus. SFTS disease has been reported throughout East Asia since 2009 and is characterized by high fever, thrombocytopenia, and leukopenia and has a 12 to 30% case fatality rate. Due to the recent emergence of SFTSV, there has been little time to conduct research into preventative measures aimed at combatting the virus. SFTSV is listed as one of the World Health Organization’s Prioritized Pathogens for research into antiviral therapeutics and vaccine development. Here, we report 2 attenuated recombinant SFTS viruses that induce a humoral immune response in immunized ferrets and confer complete cross-genotype protection to lethal challenge. Animals infected with rHB29NSsP102A or rHB2912aaNSs (both genotype D) had a reduced viral load in both serum and tissues and presented without high fever, thrombocytopenia, or mortality associated with infection. rHB29NSsP102A- or rHB2912aaNSs-immunized animals developed a robust anti-SFTSV immune response against cross-genotype isolates of SFTSV. This immune response was capable of neutralizing live virus in a focus-reduction neutralization test (FRNT) and was 100% protective against a cross-genotype lethal challenge with the CB1/2014 strain of SFTSV (genotype B). Thus, using our midsized, aged ferret infection model, we demonstrate 2 live attenuated vaccine candidates against the emerging pathogen SFTSV.
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Immune Modulation and Immune-Mediated Pathogenesis of Emerging Tickborne Banyangviruses. Vaccines (Basel) 2019; 7:vaccines7040125. [PMID: 31547199 PMCID: PMC6963857 DOI: 10.3390/vaccines7040125] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Revised: 09/17/2019] [Accepted: 09/18/2019] [Indexed: 12/21/2022] Open
Abstract
In the last decade, the emergence of several, novel tickborne viruses have caused significant disease in humans. Of interest are the tickborne banyangviruses: Severe fever with thrombocytopenia syndrome virus (SFTSV), Heartland virus (HRTV), and Guertu virus (GTV). SFTSV and HRTV infection in humans cause viral hemorrhagic fever-like disease leading to mortality rates ranging from 6–30% of the cases. The systemic inflammatory response syndrome (SIRS) associated with SFTSV infection is hypothesized to contribute significantly to pathology seen in patients. Despite the severe disease caused by HRTV and SFTSV, there are no approved therapeutics or vaccines. Investigation of the immune response during and following infection is critical to the generation of fully protective vaccines and/or supportive treatments, and overall understanding of viral immune evasion mechanisms may aid in the development of a new class of therapeutics.
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Ning YJ, Mo Q, Feng K, Min YQ, Li M, Hou D, Peng C, Zheng X, Deng F, Hu Z, Wang H. Interferon-γ-Directed Inhibition of a Novel High-Pathogenic Phlebovirus and Viral Antagonism of the Antiviral Signaling by Targeting STAT1. Front Immunol 2019; 10:1182. [PMID: 31191546 PMCID: PMC6546826 DOI: 10.3389/fimmu.2019.01182] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 05/09/2019] [Indexed: 12/20/2022] Open
Abstract
Severe fever with thrombocytopenia syndrome (SFTS) is a life-threatening infectious disease caused by a novel phlebovirus, SFTS virus (SFTSV). Currently, there is no vaccine or antiviral available and the viral pathogenesis remains largely unknown. In this study, we demonstrated that SFTSV infection results in substantial production of serum interferon-γ (IFN-γ) in patients and then that IFN-γ in turn exhibits a robust anti-SFTSV activity in cultured cells, indicating the potential role of IFN-γ in anti-SFTSV immune responses. However, the IFN-γ anti-SFTSV efficacy was compromised once viral infection had been established. Consistently, we found that viral nonstructural protein (NSs) expression counteracts IFN-γ signaling. By protein interaction analyses combined with mass spectrometry, we identified the transcription factor of IFN-γ signaling pathway, STAT1, as the cellular target of SFTSV for IFN-γ antagonism. Mechanistically, SFTSV blocks IFN-γ-triggered STAT1 action through (1) NSs-STAT1 interaction-mediated sequestration of STAT1 into viral inclusion bodies and (2) viral infection-induced downregulation of STAT1 protein level. Finally, the efficacy of IFN-γ as an anti-SFTSV drug in vivo was evaluated in a mouse infection model: IFN-γ pretreatment but not posttreatment conferred significant protection to mice against lethal SFTSV infection, confirming IFN-γ's anti-SFTSV effect and viral antagonism against IFN-γ after the infection establishment. These findings present a picture of virus-host arm race and may promote not only the understanding of virus-host interactions and viral pathogenesis but also the development of antiviral therapeutics.
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Affiliation(s)
- Yun-Jia Ning
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Qiong Mo
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Kuan Feng
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Yuan-Qin Min
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Mingyue Li
- Department of Infectious Diseases, Union Hospital, Institute of Infection and Immunology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Dianhai Hou
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Cheng Peng
- Department of Infectious Diseases, Union Hospital, Institute of Infection and Immunology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xin Zheng
- Department of Infectious Diseases, Union Hospital, Institute of Infection and Immunology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Fei Deng
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Zhihong Hu
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Hualin Wang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
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Species-Specific Pathogenicity of Severe Fever with Thrombocytopenia Syndrome Virus Is Determined by Anti-STAT2 Activity of NSs. J Virol 2019; 93:JVI.02226-18. [PMID: 30814285 DOI: 10.1128/jvi.02226-18] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 02/14/2019] [Indexed: 11/20/2022] Open
Abstract
Severe fever with thrombocytopenia syndrome virus (SFTSV) is a novel emerging virus that has been identified in China, South Korea, and Japan, and it induces thrombocytopenia and leukocytopenia in humans with a high case fatality rate. SFTSV is pathogenic to humans, while immunocompetent adult mice and golden Syrian hamsters infected with SFTSV never show apparent symptoms. However, mice deficient for the gene encoding the α chain of the alpha- and beta-interferon receptor (Ifnar1-/- mice) and golden Syrian hamsters deficient for the gene encoding signal transducer and activator of transcription 2 (Stat2-/- hamsters) are highly susceptible to SFTSV infection, with infection resulting in death. The nonstructural protein (NSs) of SFTSV has been reported to inhibit the type I IFN response through sequestration of human STAT proteins. Here, we demonstrated that SFTSV induces lethal acute disease in STAT2-deficient mice but not in STAT1-deficient mice. Furthermore, we discovered that NSs cannot inhibit type I IFN signaling in murine cells due to an inability to bind to murine STAT2. Taken together, our results imply that the dysfunction of NSs in antagonizing murine STAT2 can lead to inefficient replication and the loss of pathogenesis of SFTSV in mice.IMPORTANCE Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease caused by SFTSV, which has been reported in China, South Korea, and Japan. Here, we revealed that mice lacking STAT2, which is an important factor for antiviral innate immunity, are highly susceptible to SFTSV infection. We also show that SFTSV NSs cannot exert its anti-innate immunity activity in mice due to the inability of the protein to bind to murine STAT2. Our findings suggest that the dysfunction of SFTSV NSs as an IFN antagonist in murine cells confers a loss of pathogenicity of SFTSV in mice.
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Feng K, Deng F, Hu Z, Wang H, Ning YJ. Heartland virus antagonizes type I and III interferon antiviral signaling by inhibiting phosphorylation and nuclear translocation of STAT2 and STAT1. J Biol Chem 2019; 294:9503-9517. [PMID: 31040183 DOI: 10.1074/jbc.ra118.006563] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2018] [Revised: 04/17/2019] [Indexed: 01/30/2023] Open
Abstract
Heartland virus (HRTV) is a pathogenic phlebovirus recently identified in the United States and related to severe fever with thrombocytopenia syndrome virus (SFTSV) emerging in Asia. We previously reported that SFTSV disrupts host antiviral responses directed by interferons (IFNs) and their downstream regulators, signal transducer and activator of transcription (STAT) proteins. However, whether HRTV infection antagonizes the IFN-STAT signaling axis remains unclear. Here, we show that, similar to SFTSV, HRTV also inhibits IFN-α- and IFN-λ-mediated antiviral responses. As expected, the nonstructural protein (NSs) of HRTV (HNSs) robustly antagonized both type I and III IFN signaling. Protein interaction analyses revealed that a common component downstream of type I and III IFN signaling, STAT2, is the target of HNSs. Of note, the DNA-binding and linker domains of STAT2 were required for an efficient HNSs-STAT2 interaction. Unlike the NSs of SFTSV (SNSs), which blocks both STAT2 and STAT1 nuclear accumulation, HNSs specifically blocked IFN-triggered nuclear translocation only of STAT2. However, upon HRTV infection, IFN-induced nuclear translocation of both STAT2 and STAT1 was suppressed, suggesting that STAT1 is an additional HRTV target for IFN antagonism. Consistently, despite HNSs inhibiting phosphorylation only of STAT2 and not STAT1, HRTV infection diminished both STAT2 and STAT1 phosphorylation. These results suggest that HRTV antagonizes IFN antiviral signaling by dampening both STAT2 and STAT1 activities. We propose that HNSs-specific targeting of STAT2 likely plays an important role but is not all of the "tactics" of HRTV in its immune evasion.
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Affiliation(s)
- Kuan Feng
- From the State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China and.,the University of Chinese Academy of Sciences, Beijing 101408, China
| | - Fei Deng
- From the State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China and
| | - Zhihong Hu
- From the State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China and
| | - Hualin Wang
- From the State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China and
| | - Yun-Jia Ning
- From the State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China and
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Siu KL, Yuen KS, Castaño-Rodriguez C, Ye ZW, Yeung ML, Fung SY, Yuan S, Chan CP, Yuen KY, Enjuanes L, Jin DY. Severe acute respiratory syndrome coronavirus ORF3a protein activates the NLRP3 inflammasome by promoting TRAF3-dependent ubiquitination of ASC. FASEB J 2019; 33:8865-8877. [PMID: 31034780 DOI: 10.1096/fj.201802418r] [Citation(s) in RCA: 374] [Impact Index Per Article: 74.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Severe acute respiratory syndrome coronavirus (SARS-CoV) is capable of inducing a storm of proinflammatory cytokines. In this study, we show that the SARS-CoV open reading frame 3a (ORF3a) accessory protein activates the NLRP3 inflammasome by promoting TNF receptor-associated factor 3 (TRAF3)-mediated ubiquitination of apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC). SARS-CoV and its ORF3a protein were found to be potent activators of pro-IL-1β gene transcription and protein maturation, the 2 signals required for activation of the NLRP3 inflammasome. ORF3a induced pro-IL-1β transcription through activation of NF-κB, which was mediated by TRAF3-dependent ubiquitination and processing of p105. ORF3a-induced elevation of IL-1β secretion was independent of its ion channel activity or absent in melanoma 2 but required NLRP3, ASC, and TRAF3. ORF3a interacted with TRAF3 and ASC, colocalized with them in discrete punctate structures in the cytoplasm, and facilitated ASC speck formation. TRAF3-dependent K63-linked ubiquitination of ASC was more pronounced in SARS-CoV-infected cells or when ORF3a was expressed. Taken together, our findings reveal a new mechanism by which SARS-CoV ORF3a protein activates NF-κB and the NLRP3 inflammasome by promoting TRAF3-dependent ubiquitination of p105 and ASC.-Siu, K.-L., Yuen, K.-S., Castaño-Rodriguez, C., Ye, Z.-W., Yeung, M.-L., Fung, S.-Y., Yuan, S., Chan, C.-P., Yuen, K.-Y., Enjuanes, L., Jin, D.-Y. Severe acute respiratory syndrome coronavirus ORF3a protein activates the NLRP3 inflammasome by promoting TRAF3-dependent ubiquitination of ASC.
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Affiliation(s)
- Kam-Leung Siu
- School of Biomedical Sciences, The University of Hong Kong, PokFuLam, Hong Kong
| | - Kit-San Yuen
- School of Biomedical Sciences, The University of Hong Kong, PokFuLam, Hong Kong
| | - Carlos Castaño-Rodriguez
- Department of Molecular and Cell Biology, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC), Madrid, Spain
| | - Zi-Wei Ye
- Department of Microbiology, The University of Hong Kong, Pokfulam, Hong Kong
| | - Man-Lung Yeung
- Department of Microbiology, The University of Hong Kong, Pokfulam, Hong Kong
| | - Sin-Yee Fung
- School of Biomedical Sciences, The University of Hong Kong, PokFuLam, Hong Kong
| | - Shuofeng Yuan
- Department of Microbiology, The University of Hong Kong, Pokfulam, Hong Kong
| | - Chi-Ping Chan
- School of Biomedical Sciences, The University of Hong Kong, PokFuLam, Hong Kong
| | - Kwok-Yung Yuen
- Department of Microbiology, The University of Hong Kong, Pokfulam, Hong Kong
| | - Luis Enjuanes
- Department of Molecular and Cell Biology, Centro Nacional de Biotecnología-Consejo Superior de Investigaciones Científicas (CNB-CSIC), Madrid, Spain
| | - Dong-Yan Jin
- School of Biomedical Sciences, The University of Hong Kong, PokFuLam, Hong Kong
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Targeting SUMO Modification of the Non-Structural Protein 5 of Zika Virus as a Host-Targeting Antiviral Strategy. Int J Mol Sci 2019; 20:ijms20020392. [PMID: 30658479 PMCID: PMC6359730 DOI: 10.3390/ijms20020392] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 01/14/2019] [Accepted: 01/15/2019] [Indexed: 01/28/2023] Open
Abstract
Post-translational modifications of host or viral proteins are key strategies exploited by viruses to support virus replication and counteract host immune response. SUMOylation is a post-translational modification process mediated by a family of ubiquitin-like proteins called small ubiquitin-like modifier (SUMO) proteins. Multiple sequence alignment of 78 representative flaviviruses showed that most (72/78, 92.3%) have a putative SUMO-interacting motif (SIM) at their non-structural 5 (NS5) protein’s N-terminal domain. The putative SIM was highly conserved among 414 pre-epidemic and epidemic Zika virus (ZIKV) strains, with all of them having a putative SIM core amino acid sequence of VIDL (327/414, 79.0%) or VVDL (87/414, 21.0%). Molecular docking predicted that the hydrophobic SIM core residues bind to the β2 strand of the SUMO-1 protein, and the acidic residues flanking the core strengthen the binding through interactions with the basic surface of the SUMO protein. The SUMO inhibitor 2-D08 significantly reduced replication of flaviviruses and protected cells against ZIKV-induced cytopathic effects in vitro. A SIM-mutated ZIKV NS5 failed to efficiently suppress type I interferon signaling. Overall, these findings may suggest SUMO modification of the viral NS5 protein to be an evolutionarily conserved post-translational modification process among flaviviruses to enhance virus replication and suppress host antiviral response.
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Severe fever with thrombocytopenia syndrome phlebovirus non-structural protein activates TPL2 signalling pathway for viral immunopathogenesis. Nat Microbiol 2019; 4:429-437. [PMID: 30617349 DOI: 10.1038/s41564-018-0329-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 11/23/2018] [Indexed: 02/02/2023]
Abstract
Severe fever with thrombocytopenia syndrome phlebovirus (SFTSV), listed in the World Health Organization Prioritized Pathogens, is an emerging phlebovirus with a high fatality1-4. Owing to the lack of therapies and vaccines5,6, there is a pressing need to understand SFTSV pathogenesis. SFSTV non-structural protein (NSs) has been shown to block type I interferon induction7-11 and facilitate disease progression12,13. Here, we report that SFTSV-NSs targets the tumour progression locus 2 (TPL2)-A20-binding inhibitor of NF-κB activation 2 (ABIN2)-p105 complex to induce the expression of interleukin-10 (IL-10) for viral pathogenesis. Using a combination of reverse genetics, a TPL2 kinase inhibitor and Tpl2-/- mice showed that NSs interacted with ABIN2 and promoted TPL2 complex formation and signalling activity, resulting in the marked upregulation of Il10 expression. Whereas SFTSV infection of wild-type mice led to rapid weight loss and death, Tpl2-/- mice or Il10-/- mice survived an infection. Furthermore, SFTSV-NSs P102A and SFTSV-NSs K211R that lost the ability to induce TPL2 signalling and IL-10 production showed drastically reduced pathogenesis. Remarkably, the exogenous administration of recombinant IL-10 effectively rescued the attenuated pathogenic activity of SFTSV-NSs P102A, resulting in a lethal infection. Our study demonstrates that SFTSV-NSs targets the TPL2 signalling pathway to induce immune-suppressive IL-10 cytokine production as a means to dampen the host defence and promote viral pathogenesis.
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NSs Protein of Sandfly Fever Sicilian Phlebovirus Counteracts Interferon (IFN) Induction by Masking the DNA-Binding Domain of IFN Regulatory Factor 3. J Virol 2018; 92:JVI.01202-18. [PMID: 30232186 PMCID: PMC6232482 DOI: 10.1128/jvi.01202-18] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 09/13/2018] [Indexed: 12/25/2022] Open
Abstract
Sandfly fever Sicilian virus (SFSV) is one of the most widespread and frequently identified members of the genus Phlebovirus (order Bunyavirales, family Phenuiviridae) infecting humans. Being transmitted by Phlebotomus sandflies, SFSV causes a self-limiting, acute, often incapacitating febrile disease ("sandfly fever," "Pappataci fever," or "dog disease") that has been known since at least the beginning of the 20th century. We show that, similarly to other pathogenic phleboviruses, SFSV suppresses the induction of the antiviral type I interferon (IFN) system in an NSs-dependent manner. SFSV NSs interfered with the TBK1-interferon regulatory factor 3 (IRF3) branch of the RIG-I signaling pathway but not with NF-κB activation. Consistently, we identified IRF3 as a host interactor of SFSV NSs. In contrast to IRF3, neither the IFN master regulator IRF7 nor any of the related transcription factors IRF2, IRF5, and IRF9 were bound by SFSV NSs. In spite of this specificity for IRF3, NSs did not inhibit its phosphorylation, dimerization, or nuclear accumulation, and the interaction was independent of the IRF3 activation or multimerization state. In further studies, we identified the DNA-binding domain of IRF3 (amino acids 1 to 113) as sufficient for NSs binding and found that SFSV NSs prevented the association of activated IRF3 with the IFN-β promoter. Thus, unlike highly virulent phleboviruses, which either destroy antiviral host factors or sequester whole signaling chains into inactive aggregates, SFSV modulates type I IFN induction by directly masking the DNA-binding domain of IRF3.IMPORTANCE Phleboviruses are receiving increased attention due to the constant discovery of new species and the ongoing spread of long-known members of the genus. Outbreaks of sandfly fever were reported in the 19th century, during World War I, and during World War II. Currently, SFSV is recognized as one of the most widespread phleboviruses, exhibiting high seroprevalence rates in humans and domestic animals and causing a self-limiting but incapacitating disease predominantly in immunologically naive troops and travelers. We show how the nonstructural NSs protein of SFSV counteracts the upregulation of the antiviral interferon (IFN) system. SFSV NSs specifically inhibits promoter binding by IFN transcription factor 3 (IRF3), a molecular strategy which is unique among phleboviruses and, to our knowledge, among human pathogenic RNA viruses in general. This IRF3-specific and stoichiometric mechanism, greatly distinct from the ones exhibited by the highly virulent phleboviruses, correlates with the intermediate level of pathogenicity of SFSV.
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Two Conserved Amino Acids within the NSs of Severe Fever with Thrombocytopenia Syndrome Phlebovirus Are Essential for Anti-interferon Activity. J Virol 2018; 92:JVI.00706-18. [PMID: 30021900 DOI: 10.1128/jvi.00706-18] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 07/13/2018] [Indexed: 01/14/2023] Open
Abstract
The nonstructural protein (NSs) of severe fever with thrombocytopenia syndrome phlebovirus (SFTSV) sequesters TANK-binding kinase 1 (TBK1) into NSs-induced cytoplasmic structures to inhibit the phosphorylation and nuclear translocation of interferon (IFN) regulatory factor 3 (IRF3) and subsequent interferon beta (IFN-β) production. Although the C-terminal region of SFTSV NSs (NSs66-249) has been linked to the formation of NSs-induced cytoplasmic structures and inhibition of host IFN-β responses, the role of the N-terminal region in antagonizing host antiviral responses remains to be defined. Here, we demonstrate that two conserved amino acids at positions 21 and 23 in the SFTSV and heartland virus (HRTV) NSs are essential for suppression of IRF3 phosphorylation and IFN-β mRNA expression following infection with SFTSV or recombinant influenza virus lacking the NS1 gene. Surprisingly, formation of SFTSV/HRTV NSs-induced cytoplasmic structures is not essential for inhibition of host antiviral responses. Rather, an association between SFTSV/HRTV NSs and TBK1 is required for suppression of mitochondrial antiviral signaling protein (MAVS)-mediated activation of IFN-β promoter activity. Although SFTSV NSs did not prevent the ubiquitination of TBK1, it associates with TBK1 through its N-terminal kinase domain (residues 1 to 307) to block the autophosphorylation of TBK1. Furthermore, we found that both wild-type NSs and the 21/23A mutant (NSs in which residues at positions 21 and 23 were replaced with alanine) of SFTSV suppressed NLRP3 inflammasome-dependent interleukin-1β (IL-1β) secretion, suggesting that the importance of these residues is restricted to TBK1-dependent IFN signaling. Together, our findings strongly implicate the two conserved amino acids at positions 21 and 23 of SFTSV/HRTV NSs in the inhibition of host interferon responses.IMPORTANCE Recognition of viruses by host innate immune systems plays a critical role not only in providing resistance to viral infection but also in the initiation of antigen-specific adaptive immune responses against viruses. Severe fever with thrombocytopenia syndrome (SFTS) is a newly emerging infectious disease caused by the SFTS phlebovirus (SFTSV), a highly pathogenic tick-borne phlebovirus. The 294-amino-acid nonstructural protein (NSs) of SFTSV associates with TANK-binding kinase 1 (TBK1), a key regulator of host innate antiviral immunity, to inhibit interferon beta (IFN-β) production and enhance viral replication. Here, we demonstrate that two conserved amino acids at positions 21 and 23 in the NSs of SFTSV and heartland virus, another tick-borne phlebovirus, are essential for association with TBK1 and suppression of IFN-β production. Our results provide important insight into the molecular mechanisms by which SFTSV NSs helps to counteract host antiviral strategies.
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Xu XQ, Guo L, Wang X, Liu Y, Liu H, Zhou RH, Gu J, Liu JB, Xu P, Zhou L, Ho WZ. Human Cervical Epithelial Cells Release Antiviral Factors and Inhibit HIV Replication in Macrophages. J Innate Immun 2018; 11:29-40. [PMID: 30032138 DOI: 10.1159/000490586] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 06/03/2018] [Indexed: 12/11/2022] Open
Abstract
The female reproductive tract is a major site of HIV sexual transmission. We here examined whether human cervical epithelial cells (HCEs) can be immunologically activated and produce antiviral factors against HIV. We demonstrated that HCEs (End1/E6E7 cells) possess the functional toll-like receptor (TLR)3 signaling system, which could be activated by Poly I:C and induce multiple cellular HIV restriction factors. The treatment of primary human macrophages with supernatant (SN) from TLR3-activated End1/E6E7 cell cultures resulted in HIV inhibition. This SN-mediated HIV inhibition was mainly through the induction of interferons (IFN)-β and IFN-λs, as the antibodies to IFN-β or IFN-λs receptor could effectively block the SN-mediated anti-HIV effect. Further studies showed that the incubation of macrophages with SN from the activated cervical epithelial cell cultures induced the expression of a number of IFN-stimulated genes (ISGs), including IFN-stimulated gene (ISG15), ISG56, 2', 5'-oligoadenylate synthetase 1 (OAS 1), OAS 2, Myxovirus Resistance A (MxA), MxB, and Guanylate-binding protein 5 (GBP5). In addition, TLR3-activated cells produced the CC chemokines [regulated on activation, normal T cell expressed and secreted (RANTES), Human macrophage inflammatory protein 1 alpha (MIP-1α), MIP-1β] the ligands of HIV entry co-receptor CCR5. These observations support further studies on HCEs as potentially crucial and alternative targets for immunological intervention to control and prevent HIV sexual transmission.
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Affiliation(s)
- Xi-Qiu Xu
- Institute of Medical Virology, State Key Laboratory of Virology, Wuhan University School of Basic Medical Sciences, Wuhan, China
| | - Le Guo
- Institute of Medical Virology, State Key Laboratory of Virology, Wuhan University School of Basic Medical Sciences, Wuhan, China
| | - Xu Wang
- Department of Pathology and Laboratory Medicine, Temple University Lewis Katz School of Medicine, Philadelphia, Pennsylvania, USA
| | - Yu Liu
- Institute of Medical Virology, State Key Laboratory of Virology, Wuhan University School of Basic Medical Sciences, Wuhan, China
| | - Hang Liu
- Institute of Medical Virology, State Key Laboratory of Virology, Wuhan University School of Basic Medical Sciences, Wuhan, China
| | - Run-Hong Zhou
- Institute of Medical Virology, State Key Laboratory of Virology, Wuhan University School of Basic Medical Sciences, Wuhan, China
| | - Jun Gu
- Institute of Medical Virology, State Key Laboratory of Virology, Wuhan University School of Basic Medical Sciences, Wuhan, China
| | - Jin-Biao Liu
- Animal Biosafety Level III Laboratory at the Center for Animal Experiment, Wuhan University School of Medicine, Wuhan, China
| | - Pei Xu
- School of Medicine (Shenzhen), Sun Yat-sen University, Guangzhou, China
| | - Li Zhou
- Animal Biosafety Level III Laboratory at the Center for Animal Experiment, Wuhan University School of Medicine, Wuhan,
| | - Wen-Zhe Ho
- Institute of Medical Virology, State Key Laboratory of Virology, Wuhan University School of Basic Medical Sciences, Wuhan, China.,Department of Pathology and Laboratory Medicine, Temple University Lewis Katz School of Medicine, Philadelphia, Pennsylvania, USA
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Kitagawa Y, Sakai M, Shimojima M, Saijo M, Itoh M, Gotoh B. Nonstructural protein of severe fever with thrombocytopenia syndrome phlebovirus targets STAT2 and not STAT1 to inhibit type I interferon-stimulated JAK-STAT signaling. Microbes Infect 2018; 20:360-368. [PMID: 29886262 DOI: 10.1016/j.micinf.2018.05.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Revised: 05/30/2018] [Accepted: 05/31/2018] [Indexed: 01/17/2023]
Abstract
The nonstructural protein NSs of severe fever with thrombocytopenia syndrome phlebovirus blocks type I interferon (IFN)-stimulated JAK-STAT signaling. However, there is continuing controversy as to whether NSs targets STAT1 or STAT2 or both for this blockade. The present study was designed to gain a further understanding of the blockade mechanism. Immunoprecipitation experiments revealed a stronger interaction of NSs with STAT2 than with any other component constituting the JAK-STAT pathway. Expression of NSs resulted in the formation of cytoplasmic inclusion bodies (IBs), and affected cytoplasmic distribution of STAT2. STAT2 was relocated to NSs-induced IBs. Consequently, NSs inhibited IFN-α-stimulated tyrosine phosphorylation and nuclear translocation of STAT2. These inhibitory effects as well as the signaling blockade activity were not observed in NSs mutant proteins lacking the STAT2-binding ability. In contrast, NSs affected neither subcellular distribution nor phosphorylation of STAT1 in response to IFN-α and IFN-γ, demonstrating that NSs has little physical and functional interactions with STAT1. Taken together, these results suggest that NSs sequesters STAT2 into NSs-induced IBs, thereby blocking type I IFN JAK-STAT signaling.
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Affiliation(s)
- Yoshinori Kitagawa
- Division of Microbiology and Infectious Diseases, Department of Pathology, Shiga University of Medical Science, Seta Tsukinowa-cho, Otsu, Shiga, 520-2192, Japan
| | - Madoka Sakai
- Division of Microbiology and Infectious Diseases, Department of Pathology, Shiga University of Medical Science, Seta Tsukinowa-cho, Otsu, Shiga, 520-2192, Japan; Department of Microbiology, Faculty of Bio-Science, Nagahama Institute of Bio-Science and Technology, 1266 Tamura-cho, Nagahama, Shiga, 526-0829, Japan
| | - Masayuki Shimojima
- Department of Virology I, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo, 162-8640, Japan
| | - Masayuki Saijo
- Department of Virology I, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo, 162-8640, Japan
| | - Masae Itoh
- Department of Microbiology, Faculty of Bio-Science, Nagahama Institute of Bio-Science and Technology, 1266 Tamura-cho, Nagahama, Shiga, 526-0829, Japan
| | - Bin Gotoh
- Division of Microbiology and Infectious Diseases, Department of Pathology, Shiga University of Medical Science, Seta Tsukinowa-cho, Otsu, Shiga, 520-2192, Japan.
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Mapping of Transcription Termination within the S Segment of SFTS Phlebovirus Facilitated Generation of NSs Deletant Viruses. J Virol 2017; 91:JVI.00743-17. [PMID: 28592543 PMCID: PMC5533932 DOI: 10.1128/jvi.00743-17] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Accepted: 05/31/2017] [Indexed: 12/15/2022] Open
Abstract
SFTS phlebovirus (SFTSV) is an emerging tick-borne bunyavirus that was first reported in China in 2009. Here we report the generation of a recombinant SFTSV (rHB29NSsKO) that cannot express the viral nonstructural protein (NSs) upon infection of cells in culture. We show that rHB29NSsKO replication kinetics are greater in interferon (IFN)-incompetent cells and that the virus is unable to suppress IFN induced in response to viral replication. The data confirm for the first time in the context of virus infection that NSs acts as a virally encoded IFN antagonist and that NSs is dispensable for virus replication. Using 3' rapid amplification of cDNA ends (RACE), we mapped the 3' end of the N and NSs mRNAs, showing that the mRNAs terminate within the coding region of the opposite open reading frame. We show that the 3' end of the N mRNA terminates upstream of a 5'-GCCAGCC-3' motif present in the viral genomic RNA. With this knowledge, and using virus-like particles, we could demonstrate that the last 36 nucleotides of the NSs open reading frame (ORF) were needed to ensure the efficient termination of the N mRNA and were required for recombinant virus rescue. We demonstrate that it is possible to recover viruses lacking NSs (expressing just a 12-amino-acid NSs peptide or encoding enhanced green fluorescent protein [eGFP]) or an NSs-eGFP fusion protein in the NSs locus. This opens the possibility for further studies of NSs and potentially the design of attenuated viruses for vaccination studies.IMPORTANCE SFTS phlebovirus (SFTSV) and related tick-borne viruses have emerged globally since 2009. SFTSV has been shown to cause severe disease in humans. For bunyaviruses, it has been well documented that the nonstructural protein (NSs) enables the virus to counteract the human innate antiviral defenses and that NSs is one of the major determinants of virulence in infection. Therefore, the use of reverse genetics systems to engineer viruses lacking NSs is an attractive strategy to rationally attenuate bunyaviruses. Here we report the generation of several recombinant SFTS viruses that cannot express the NSs protein or have the NSs open reading frame replaced with a reporter gene. These viruses cannot antagonize the mammalian interferon (IFN) response mounted to virus infection. The generation of NSs-lacking viruses was achieved by mapping the transcriptional termination of two S-segment-derived subgenomic mRNAs, which revealed that transcription termination occurs upstream of a 5'-GCCAGCC-3' motif present in the virus genomic S RNA.
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Differential Antagonism of Human Innate Immune Responses by Tick-Borne Phlebovirus Nonstructural Proteins. mSphere 2017; 2:mSphere00234-17. [PMID: 28680969 PMCID: PMC5489658 DOI: 10.1128/msphere.00234-17] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 06/05/2017] [Indexed: 12/24/2022] Open
Abstract
In recent years, several newly discovered tick-borne viruses causing a wide spectrum of diseases in humans have been ascribed to the Phlebovirus genus of the Bunyaviridae family. The nonstructural protein (NSs) of bunyaviruses is the main virulence factor and interferon (IFN) antagonist. We studied the molecular mechanisms of IFN antagonism employed by the NSs proteins of human apathogenic Uukuniemi virus (UUKV) and those of Heartland virus (HRTV) and severe fever with thrombocytopenia syndrome virus (SFTSV), both of which cause severe disease. Using reporter assays, we found that UUKV NSs weakly inhibited the activation of the beta interferon (IFN-β) promoter and response elements. UUKV NSs weakly antagonized human IFN-β promoter activation through a novel interaction with mitochondrial antiviral-signaling protein (MAVS), confirmed by coimmunoprecipitation and confocal microscopy studies. HRTV NSs efficiently antagonized both IFN-β promoter activation and type I IFN signaling pathways through interactions with TBK1, preventing its phosphorylation. HRTV NSs exhibited diffused cytoplasmic localization. This is in comparison to the inclusion bodies formed by SFTSV NSs. HRTV NSs also efficiently interacted with STAT2 and impaired IFN-β-induced phosphorylation but did not affect STAT1 or its translocation to the nucleus. Our results suggest that a weak interaction between STAT1 and HRTV or SFTSV NSs may explain their inability to block type II IFN signaling efficiently, thus enabling the activation of proinflammatory responses that lead to severe disease. Our findings offer insights into how pathogenicity may be linked to the capacity of NSs proteins to block the innate immune system and illustrate the plethora of viral immune evasion strategies utilized by emerging phleboviruses. IMPORTANCE Since 2011, there has been a large expansion in the number of emerging tick-borne viruses that have been assigned to the Phlebovirus genus. Heartland virus (HRTV) and SFTS virus (SFTSV) were found to cause severe disease in humans, unlike other documented tick-borne phleboviruses such as Uukuniemi virus (UUKV). Phleboviruses encode nonstructural proteins (NSs) that enable them to counteract the human innate antiviral defenses. We assessed how these proteins interacted with the innate immune system. We found that UUKV NSs engaged with innate immune factors only weakly, at one early step. However, the viruses that cause more severe disease efficiently disabled the antiviral response by targeting multiple components at several stages across the innate immune induction and signaling pathways. Our results suggest a correlation between the efficiency of the virus protein/host interaction and severity of disease.
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Selective Activation of Type II Interferon Signaling by Zika Virus NS5 Protein. J Virol 2017; 91:JVI.00163-17. [PMID: 28468880 DOI: 10.1128/jvi.00163-17] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2017] [Accepted: 04/25/2017] [Indexed: 12/24/2022] Open
Abstract
Severe complications of Zika virus (ZIKV) infection might be caused by inflammation, but how ZIKV induces proinflammatory cytokines is not understood. In this study, we show opposite regulatory effects of the ZIKV NS5 protein on interferon (IFN) signaling. Whereas ZIKV and its NS5 protein were potent suppressors of type I and type III IFN signaling, they were found to activate type II IFN signaling. Inversely, IFN-γ augmented ZIKV replication. NS5 interacted with STAT2 and targeted it for ubiquitination and degradation, but it had no influence on STAT1 stability or nuclear translocation. The recruitment of STAT1-STAT2-IRF9 to IFN-β-stimulated genes was compromised when NS5 was expressed. Concurrently, the formation of STAT1-STAT1 homodimers and their recruitment to IFN-γ-stimulated genes, such as the gene encoding the proinflammatory cytokine CXCL10, were augmented. Silencing the expression of an IFN-γ receptor subunit or treatment of ZIKV-infected cells with a JAK2 inhibitor suppressed viral replication and viral induction of IFN-γ-stimulated genes. Taken together, our findings provide a new mechanism by which the ZIKV NS5 protein differentially regulates IFN signaling to facilitate viral replication and cause diseases. This activity might be shared by a group of viral IFN modulators.IMPORTANCE Mammalian cells produce three types of interferons to combat viral infection and to control host immune responses. To replicate and cause diseases, pathogenic viruses have developed different strategies to defeat the action of host interferons. Many viral proteins, including the Zika virus (ZIKV) NS5 protein, are known to be able to suppress the antiviral property of type I and type III interferons. Here we further show that the ZIKV NS5 protein can also boost the activity of type II interferon to induce cellular proteins that promote inflammation. This is mediated by the differential effect of the ZIKV NS5 protein on a pair of cellular transcription factors, STAT1 and STAT2. NS5 induces the degradation of STAT2 but promotes the formation of STAT1-STAT1 protein complexes, which activate genes controlled by type II interferon. A drug that specifically inhibits the IFN-γ receptor or STAT1 shows an anti-ZIKV effect and might also have anti-inflammatory activity.
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Drake MJ, Brennan B, Briley Jr K, Bart SM, Sherman E, Szemiel AM, Minutillo M, Bushman FD, Bates P. A role for glycolipid biosynthesis in severe fever with thrombocytopenia syndrome virus entry. PLoS Pathog 2017; 13:e1006316. [PMID: 28388693 PMCID: PMC5397019 DOI: 10.1371/journal.ppat.1006316] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Revised: 04/19/2017] [Accepted: 03/24/2017] [Indexed: 01/01/2023] Open
Abstract
A novel bunyavirus was recently found to cause severe febrile illness with high mortality in agricultural regions of China, Japan, and South Korea. This virus, named severe fever with thrombocytopenia syndrome virus (SFTSV), represents a new group within the Phlebovirus genus of the Bunyaviridae. Little is known about the viral entry requirements beyond showing dependence on dynamin and endosomal acidification. A haploid forward genetic screen was performed to identify host cell requirements for SFTSV entry. The screen identified dependence on glucosylceramide synthase (ugcg), the enzyme responsible for initiating de novo glycosphingolipid biosynthesis. Genetic and pharmacological approaches confirmed that UGCG expression and enzymatic activity were required for efficient SFTSV entry. Furthermore, inhibition of UGCG affected a post-internalization stage of SFTSV entry, leading to the accumulation of virus particles in enlarged cytoplasmic structures, suggesting impaired trafficking and/or fusion of viral and host membranes. These findings specify a role for glucosylceramide in SFTSV entry and provide a novel target for antiviral therapies.
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Affiliation(s)
- Mary Jane Drake
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Benjamin Brennan
- MRC-University of Glasgow Centre for Virus Research, University of Glasgow, Glasgow, United Kingdom
| | - Kenneth Briley Jr
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Stephen M. Bart
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Eric Sherman
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Agnieszka M. Szemiel
- MRC-University of Glasgow Centre for Virus Research, University of Glasgow, Glasgow, United Kingdom
| | - Madeleine Minutillo
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Frederic D. Bushman
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Paul Bates
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
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50
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Chen X, Ye H, Li S, Jiao B, Wu J, Zeng P, Chen L. Severe fever with thrombocytopenia syndrome virus inhibits exogenous Type I IFN signaling pathway through its NSs invitro. PLoS One 2017; 12:e0172744. [PMID: 28234991 PMCID: PMC5325526 DOI: 10.1371/journal.pone.0172744] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 02/08/2017] [Indexed: 12/18/2022] Open
Abstract
Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease caused by a novel bunyavirus (SFTS virus, SFTSV). At present there is still no specific antiviral treatment for SFTSV; To understand which cells support SFTSV life cycle and whether SFTSV infection activates host innate immunity, four different cell lines (Vero, Hela, Huh7.5.1, and Huh7.0) were infected with SFTSV. Intracellular/extracellular viral RNA and expression of IFNα, and IFNß were detected by real-time RT- PCR following infection. To confirm the role of non-structural protein (NSs) of SFTSV in exogenous IFNα-induced Jak/STAT signaling, p-STAT1 (Western Blot), ISRE activity (Luciferase assay) and ISG expression (real-time PCR) were examined following IFNα stimulation in the presence or absence of over-expression of NSs in Hela cells. Our study showed that all the four cell lines supported SFTSV life cycle and SFTSV activated host innate immunity to produce type I IFNs in Hela cells but not in Huh7.0, Huh7.5.1 or Vero cells. NSs inhibited exogenous IFNα-induced Jak/STAT signaling as shown by decreased p-STAT1 level, suppressed ISRE activity and down-regulated ISG expression. Suppression of the exogenous Type I IFN-induced Jak/STAT signaling by NSs might be one of the mechanisms of SFTSV to evade host immune surveillance.
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Affiliation(s)
- Xu Chen
- Institute of Blood Transfusion, Chinese Academic of Medical Sciences and Peking Union Medical College, Chengdu, China
| | - Haiyan Ye
- Institute of Blood Transfusion, Chinese Academic of Medical Sciences and Peking Union Medical College, Chengdu, China
| | - Shilin Li
- Institute of Blood Transfusion, Chinese Academic of Medical Sciences and Peking Union Medical College, Chengdu, China
| | - Baihai Jiao
- Institute of Blood Transfusion, Chinese Academic of Medical Sciences and Peking Union Medical College, Chengdu, China
| | - Jianqin Wu
- Institute of Blood Transfusion, Chinese Academic of Medical Sciences and Peking Union Medical College, Chengdu, China
| | - Peibin Zeng
- West China School of Public Health, Sichuan University, Chengdu, Sichuan, China
- * E-mail: (PZ); (LC)
| | - Limin Chen
- Institute of Blood Transfusion, Chinese Academic of Medical Sciences and Peking Union Medical College, Chengdu, China
- Toronto General Research Institute, University of Toronto, Toronto, Ontario, Canada
- * E-mail: (PZ); (LC)
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