1
|
Zhou Y, Chen Z, Liu S, Liu S, Liao Y, Du A, Dong Z, Zhang Y, Chen X, Tao S, Wu X, Razzaq A, Xu G, Tan DA, Li S, Deng Y, Peng J, Dai S, Deng X, Zhang X, Jiang T, Zhang Z, Cheng G, Zhao J, Xia Z. A Cullin 5-based complex serves as an essential modulator of ORF9b stability in SARS-CoV-2 replication. Signal Transduct Target Ther 2024; 9:159. [PMID: 38937432 PMCID: PMC11211426 DOI: 10.1038/s41392-024-01874-5] [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] [Received: 10/29/2023] [Revised: 04/12/2024] [Accepted: 05/15/2024] [Indexed: 06/29/2024] Open
Abstract
The ORF9b protein, derived from the nucleocapsid's open-reading frame in both SARS-CoV and SARS-CoV-2, serves as an accessory protein crucial for viral immune evasion by inhibiting the innate immune response. Despite its significance, the precise regulatory mechanisms underlying its function remain elusive. In the present study, we unveil that the ORF9b protein of SARS-CoV-2, including emerging mutant strains like Delta and Omicron, can undergo ubiquitination at the K67 site and subsequent degradation via the proteasome pathway, despite certain mutations present among these strains. Moreover, our investigation further uncovers the pivotal role of the translocase of the outer mitochondrial membrane 70 (TOM70) as a substrate receptor, bridging ORF9b with heat shock protein 90 alpha (HSP90α) and Cullin 5 (CUL5) to form a complex. Within this complex, CUL5 triggers the ubiquitination and degradation of ORF9b, acting as a host antiviral factor, while HSP90α functions to stabilize it. Notably, treatment with HSP90 inhibitors such as GA or 17-AAG accelerates the degradation of ORF9b, leading to a pronounced inhibition of SARS-CoV-2 replication. Single-cell sequencing data revealed an up-regulation of HSP90α in lung epithelial cells from COVID-19 patients, suggesting a potential mechanism by which SARS-CoV-2 may exploit HSP90α to evade the host immunity. Our study identifies the CUL5-TOM70-HSP90α complex as a critical regulator of ORF9b protein stability, shedding light on the intricate host-virus immune response dynamics and offering promising avenues for drug development against SARS-CoV-2 in clinical settings.
Collapse
Affiliation(s)
- Yuzheng Zhou
- Department of Cell Biology, School of Life Sciences, Central South University, 410013, Changsha, China
- Institute for Hepatology, National Clinical Research Center for Infectious Disease, Shenzhen Third People's Hospital, The Second Affiliated Hospital, School of Medicine, Southern University of Science and Technology, 518112, Shenzhen, China
| | - Zongpeng Chen
- Department of Cell Biology, School of Life Sciences, Central South University, 410013, Changsha, China
| | - Sijie Liu
- Department of Cell Biology, School of Life Sciences, Central South University, 410013, Changsha, China
| | - Sixu Liu
- Department of Cell Biology, School of Life Sciences, Central South University, 410013, Changsha, China
| | - Yujie Liao
- Department of Cell Biology, School of Life Sciences, Central South University, 410013, Changsha, China
| | - Ashuai Du
- Department of Cell Biology, School of Life Sciences, Central South University, 410013, Changsha, China
| | - Zijun Dong
- Department of Basic Medicine, School of Medicine, Hunan Normal University, 410081, Changsha, China
| | - Yongxing Zhang
- Department of Cell Biology, School of Life Sciences, Central South University, 410013, Changsha, China
| | - Xuan Chen
- Department of Cell Biology, School of Life Sciences, Central South University, 410013, Changsha, China
| | - Siyi Tao
- Department of Cell Biology, School of Life Sciences, Central South University, 410013, Changsha, China
| | - Xin Wu
- Department of spine surgery, The Third Xiangya Hospital, Central South University, 410013, Changsha, China
| | - Aroona Razzaq
- Department of Cell Biology, School of Life Sciences, Central South University, 410013, Changsha, China
| | - Gang Xu
- School of Basic Medical Sciences, Anhui Medical University, 230032, Hefei, China
| | - De-An Tan
- Hunan Key Laboratory of Neurorestoratology, 921 Hospital of Joint Logistics Support Force People's Liberation Army of China (The Second Affiliated Hospital of Hunan Normal University), 410003, Changsha, Hunan, China
| | - Shanni Li
- Department of Cell Biology, School of Life Sciences, Central South University, 410013, Changsha, China
| | - Youwen Deng
- Department of spine surgery, The Third Xiangya Hospital, Central South University, 410013, Changsha, China
| | - Jian Peng
- Department of Geriatric Surgery, Xiangya Hospital, Central South University, 410008, Changsha, China
| | - Shuyan Dai
- Xiangya School of Pharmaceutical Sciences, Central South University, 410013, Changsha, China
| | - Xu Deng
- Xiangya School of Pharmaceutical Sciences, Central South University, 410013, Changsha, China
| | - Xianwen Zhang
- Institute of Infectious Diseases, Shenzhen Bay Laboratory, 518132, Shenzhen, China
| | | | - Zheng Zhang
- Institute for Hepatology, National Clinical Research Center for Infectious Disease, Shenzhen Third People's Hospital, The Second Affiliated Hospital, School of Medicine, Southern University of Science and Technology, 518112, Shenzhen, China
| | - Gong Cheng
- Institute of Infectious Diseases, Shenzhen Bay Laboratory, 518132, Shenzhen, China
- Tsinghua University-Peking University Joint Center for Life Sciences, School of Medicine, Tsinghua University, 100084, Beijing, China
| | - Jincun Zhao
- Institute for Hepatology, National Clinical Research Center for Infectious Disease, Shenzhen Third People's Hospital, The Second Affiliated Hospital, School of Medicine, Southern University of Science and Technology, 518112, Shenzhen, China
- Guangzhou Laboratory, 510005, Guangzhou, China
- State Key Laboratory of Respiratory Disease, National Clinical Research Center for Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, 510120, Guangzhou, China
| | - Zanxian Xia
- Department of Cell Biology, School of Life Sciences, Central South University, 410013, Changsha, China.
- Hunan Key Laboratory of Animal Models for Human Diseases, Hunan Key Laboratory of Medical Genetics & Center for Medical Genetics, School of Life Sciences, Central South University, 410008, Changsha, China.
| |
Collapse
|
2
|
Waman VP, Ashford P, Lam SD, Sen N, Abbasian M, Woodridge L, Goldtzvik Y, Bordin N, Wu J, Sillitoe I, Orengo CA. Predicting human and viral protein variants affecting COVID-19 susceptibility and repurposing therapeutics. Sci Rep 2024; 14:14208. [PMID: 38902252 PMCID: PMC11190248 DOI: 10.1038/s41598-024-61541-1] [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] [Received: 11/07/2023] [Accepted: 05/07/2024] [Indexed: 06/22/2024] Open
Abstract
The COVID-19 disease is an ongoing global health concern. Although vaccination provides some protection, people are still susceptible to re-infection. Ostensibly, certain populations or clinical groups may be more vulnerable. Factors causing these differences are unclear and whilst socioeconomic and cultural differences are likely to be important, human genetic factors could influence susceptibility. Experimental studies indicate SARS-CoV-2 uses innate immune suppression as a strategy to speed-up entry and replication into the host cell. Therefore, it is necessary to understand the impact of variants in immunity-associated human proteins on susceptibility to COVID-19. In this work, we analysed missense coding variants in several SARS-CoV-2 proteins and their human protein interactors that could enhance binding affinity to SARS-CoV-2. We curated a dataset of 19 SARS-CoV-2: human protein 3D-complexes, from the experimentally determined structures in the Protein Data Bank and models built using AlphaFold2-multimer, and analysed the impact of missense variants occurring in the protein-protein interface region. We analysed 468 missense variants from human proteins and 212 variants from SARS-CoV-2 proteins and computationally predicted their impacts on binding affinities for the human viral protein complexes. We predicted a total of 26 affinity-enhancing variants from 13 human proteins implicated in increased binding affinity to SARS-CoV-2. These include key-immunity associated genes (TOMM70, ISG15, IFIH1, IFIT2, RPS3, PALS1, NUP98, AXL, ARF6, TRIMM, TRIM25) as well as important spike receptors (KREMEN1, AXL and ACE2). We report both common (e.g., Y13N in IFIH1) and rare variants in these proteins and discuss their likely structural and functional impact, using information on known and predicted functional sites. Potential mechanisms associated with immune suppression implicated by these variants are discussed. Occurrence of certain predicted affinity-enhancing variants should be monitored as they could lead to increased susceptibility and reduced immune response to SARS-CoV-2 infection in individuals/populations carrying them. Our analyses aid in understanding the potential impact of genetic variation in immunity-associated proteins on COVID-19 susceptibility and help guide drug-repurposing strategies.
Collapse
Affiliation(s)
- Vaishali P Waman
- Institute of Structural and Molecular Biology, University College London, London, WC1E 6BT, UK
| | - Paul Ashford
- Institute of Structural and Molecular Biology, University College London, London, WC1E 6BT, UK
| | - Su Datt Lam
- Department of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi, Malaysia
| | - Neeladri Sen
- Institute of Structural and Molecular Biology, University College London, London, WC1E 6BT, UK
| | - Mahnaz Abbasian
- Institute of Structural and Molecular Biology, University College London, London, WC1E 6BT, UK
| | - Laurel Woodridge
- Institute of Structural and Molecular Biology, University College London, London, WC1E 6BT, UK
| | - Yonathan Goldtzvik
- Institute of Structural and Molecular Biology, University College London, London, WC1E 6BT, UK
| | - Nicola Bordin
- Institute of Structural and Molecular Biology, University College London, London, WC1E 6BT, UK
| | - Jiaxin Wu
- Institute of Structural and Molecular Biology, University College London, London, WC1E 6BT, UK
| | - Ian Sillitoe
- Institute of Structural and Molecular Biology, University College London, London, WC1E 6BT, UK
| | - Christine A Orengo
- Institute of Structural and Molecular Biology, University College London, London, WC1E 6BT, UK.
| |
Collapse
|
3
|
Yu M, Li J, Gao W, Li Z, Zhang W. Multiple E3 ligases act as antiviral factors against SARS-CoV-2 via inducing the ubiquitination and degradation of ORF9b. J Virol 2024; 98:e0162423. [PMID: 38709105 DOI: 10.1128/jvi.01624-23] [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] [Received: 10/18/2023] [Accepted: 04/07/2024] [Indexed: 05/07/2024] Open
Abstract
Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) open reading frame 9b (ORF9b) antagonizes the antiviral type I and III interferon (IFN) responses and is ubiquitinated and degraded via the ubiquitin-proteasome pathway. However, E3 ubiquitin ligases that mediate the polyubiquitination and degradation of ORF9b remain unknown. In this study, we identified 14 E3 ligases that specifically bind to SARS-CoV-2 ORF9b. Specifically, three E3 ligases, HECT, UBA, and WWE domain-containing E3 ubiquitin protein ligase 1 (HUWE1), ubiquitin protein ligase E3 component n-recognin 4 (UBR4), and UBR5, induced K48-linked polyubiquitination and degradation of ORF9b, thereby attenuating ORF9b-mediated inhibition of the IFN response and SARS-CoV-2 replication. Moreover, each E3 ligase performed this function independent of the other two E3 ligases. Therefore, the three E3 ligases identified in this study as anti-SARS-CoV-2 host factors provide novel molecular insight into the virus-host interaction.IMPORTANCEUbiquitination is an important post-translational modification that regulates multiple biological processes, including viral replication. Identification of E3 ubiquitin ligases that target viral proteins for degradation can provide novel targets for antagonizing viral infections. Here, we identified multiple E3 ligases, including HECT, UBA, and WWE domain-containing E3 ubiquitin protein ligase 1 (HUWE1), ubiquitin protein ligase E3 component n-recognin 4 (UBR4), and UBR5, that ubiquitinated and induced the degradation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) open reading frame 9b (ORF9b), an interferon (IFN) antagonist, thereby enhancing IFN production and attenuating SARS-CoV-2 replication. Our study provides new possibilities for drug development targeting the interaction between E3 ligases and ORF9b.
Collapse
Affiliation(s)
- Miao Yu
- Department of Infectious Diseases, Infectious Diseases and Pathogen Biology Center, Key Laboratory of Organ Regeneration and Transplantation of The Ministry of Education, The First Hospital of Jilin University, Changchun, Jilin, China
- Department of Geriatrics and Special medical treatment, The First Hospital of Jilin University, Changchun, Jilin, China
| | - Jie Li
- Department of Geriatrics and Special medical treatment, The First Hospital of Jilin University, Changchun, Jilin, China
| | - Wenying Gao
- Department of Infectious Diseases, Infectious Diseases and Pathogen Biology Center, Key Laboratory of Organ Regeneration and Transplantation of The Ministry of Education, The First Hospital of Jilin University, Changchun, Jilin, China
- Institute of Virology and AIDS Research, The First Hospital of Jilin University, Changchun, Jilin, China
| | - Zhaolong Li
- Department of Infectious Diseases, Infectious Diseases and Pathogen Biology Center, Key Laboratory of Organ Regeneration and Transplantation of The Ministry of Education, The First Hospital of Jilin University, Changchun, Jilin, China
- Institute of Virology and AIDS Research, The First Hospital of Jilin University, Changchun, Jilin, China
| | - Wenyan Zhang
- Department of Infectious Diseases, Infectious Diseases and Pathogen Biology Center, Key Laboratory of Organ Regeneration and Transplantation of The Ministry of Education, The First Hospital of Jilin University, Changchun, Jilin, China
- Institute of Virology and AIDS Research, The First Hospital of Jilin University, Changchun, Jilin, China
| |
Collapse
|
4
|
Caobi A, Saeed M. Upping the ante: enhanced expression of interferon-antagonizing ORF6 and ORF9b proteins by SARS-CoV-2 variants of concern. Curr Opin Microbiol 2024; 79:102454. [PMID: 38518551 PMCID: PMC11162932 DOI: 10.1016/j.mib.2024.102454] [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: 01/09/2024] [Revised: 02/24/2024] [Accepted: 02/25/2024] [Indexed: 03/24/2024]
Abstract
SARS-CoV-2 exhibits a remarkable capability to subvert the host antiviral innate immune system. This adeptness is orchestrated by viral proteins, which initially attempt to obstruct the activation of the antiviral immune program and then act as a fail-safe mechanism to mitigate the downstream effects of the activated immune response. This dual strategy leads to delayed expression and enfeebled action of type-I and -III interferons at the infection site, enabling the virus to replicate extensively in the lungs and subsequently disseminate to other organs. Throughout the course of the COVID-19 pandemic, SARS-CoV-2 has undergone evolution, giving rise to several variants of concern, some with exceedingly higher transmission and virulence. These improved features have been linked, at least in part, to the heightened expression or activity of specific viral proteins involved in circumventing host defense mechanisms. In this review, we aim to provide a concise summary of two SARS-CoV-2 proteins, ORF6 and ORF9b, which provided selective advantage to certain variants, affecting their biology and pathogenesis.
Collapse
Affiliation(s)
- Allen Caobi
- Department of Biochemistry and Cell Biology, Boston University Chobanian and Avedisian School of Medicine, Boston, MA 02118, USA; National Emerging Infectious Diseases Laboratories (NEIDL), Boston University, Boston, MA 02118, USA
| | - Mohsan Saeed
- Department of Biochemistry and Cell Biology, Boston University Chobanian and Avedisian School of Medicine, Boston, MA 02118, USA; National Emerging Infectious Diseases Laboratories (NEIDL), Boston University, Boston, MA 02118, USA.
| |
Collapse
|
5
|
den Brave F, Pfanner N, Becker T. Mitochondrial entry gate as regulatory hub. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119529. [PMID: 37951505 DOI: 10.1016/j.bbamcr.2023.119529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2023] [Revised: 06/18/2023] [Accepted: 06/23/2023] [Indexed: 11/14/2023]
Abstract
Mitochondria import 1000-1300 different precursor proteins from the cytosol. The main mitochondrial entry gate is formed by the translocase of the outer membrane (TOM complex). Molecular coupling and modification of TOM subunits control and modulate protein import in response to cellular signaling. The TOM complex functions as regulatory hub to integrate mitochondrial protein biogenesis and quality control into the cellular proteostasis network.
Collapse
Affiliation(s)
- Fabian den Brave
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, 53115 Bonn, Germany
| | - Nikolaus Pfanner
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, 79104 Freiburg, Germany; CIBSS Centre for Integrative Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany.
| | - Thomas Becker
- Institute of Biochemistry and Molecular Biology, Faculty of Medicine, University of Bonn, 53115 Bonn, Germany.
| |
Collapse
|
6
|
Noh SS, Shin HJ. RSV Induces Activation of Intracellular EGFR on the Mitochondrial Membrane for Virus Propagation. Int J Mol Sci 2023; 24:17431. [PMID: 38139259 PMCID: PMC10744162 DOI: 10.3390/ijms242417431] [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] [Received: 11/17/2023] [Revised: 12/05/2023] [Accepted: 12/11/2023] [Indexed: 12/24/2023] Open
Abstract
Respiratory syncytial virus (RSV) infects people of all ages and is one of the most common causative agents of lower respiratory tract infections, such as pneumonia, especially in infants under one year of age. However, no direct treatment has been developed for RSV infections. Maintenance of mitochondrial homeostasis and epidermal growth factor receptor (EGFR) activity is important for human cell growth. This study reported that RSV infection maintained the total cellular ATP levels and promoted the intracellular activity of EGFR to replicate RSV. RSV activates the intracellular EGFR-mediated cell survival signaling cascade and maintains mitochondrial EGFR expression for viral production during early events after infection. The approved EGFR inhibitor, vandetanib, markedly reduces RSV propagation, suggesting that EGFR is an attractive host target for RSV therapeutics. Our results suggest that RSV infection maintains cellular ATP levels and promotes the activation of intracellular EGFR in the mitochondrial membrane, significantly contributing to robust RSV propagation.
Collapse
Affiliation(s)
- Se Sil Noh
- Department of Microbiology, School of Medicine, Chungnam National University, Daejeon 35015, Republic of Korea;
- Department of Medical Science, School of Medicine, Chungnam National University, Daejeon 35015, Republic of Korea
- Brain Korea 21 FOUR Project for Medical Science, Chungnam National University, Daejeon 35015, Republic of Korea
| | - Hye Jin Shin
- Department of Microbiology, School of Medicine, Chungnam National University, Daejeon 35015, Republic of Korea;
- Department of Medical Science, School of Medicine, Chungnam National University, Daejeon 35015, Republic of Korea
- Research Institute for Medical Sciences, School of Medicine, Chungnam National University, Daejeon 35015, Republic of Korea
| |
Collapse
|
7
|
Lenhard S, Gerlich S, Khan A, Rödl S, Bökenkamp JE, Peker E, Zarges C, Faust J, Storchova Z, Räschle M, Riemer J, Herrmann JM. The Orf9b protein of SARS-CoV-2 modulates mitochondrial protein biogenesis. J Cell Biol 2023; 222:e202303002. [PMID: 37682539 PMCID: PMC10491932 DOI: 10.1083/jcb.202303002] [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: 03/01/2023] [Revised: 07/06/2023] [Accepted: 08/07/2023] [Indexed: 09/09/2023] Open
Abstract
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) expresses high amounts of the protein Orf9b to target the mitochondrial outer membrane protein Tom70. Tom70 serves as an import receptor for mitochondrial precursors and, independently of this function, is critical for the cellular antiviral response. Previous studies suggested that Orf9b interferes with Tom70-mediated antiviral signaling, but its implication for mitochondrial biogenesis is unknown. In this study, we expressed Orf9b in human HEK293 cells and observed an Orf9b-mediated depletion of mitochondrial proteins, particularly in respiring cells. To exclude that the observed depletion was caused by the antiviral response, we generated a yeast system in which the function of human Tom70 could be recapitulated. Upon expression of Orf9b in these cells, we again observed a specific decline of a subset of mitochondrial proteins and a general reduction of mitochondrial volume. Thus, the SARS-CoV-2 virus is able to modulate the mitochondrial proteome by a direct effect of Orf9b on mitochondrial Tom70-dependent protein import.
Collapse
Affiliation(s)
- Svenja Lenhard
- Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Sarah Gerlich
- Biochemistry, University of Cologne, Cologne, Germany
- CECAD, University of Cologne, Cologne, Germany
| | - Azkia Khan
- Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Saskia Rödl
- Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Jan-Eric Bökenkamp
- Molecular Genetics, University of Kaiserslautern, Kaiserslautern, Germany
| | - Esra Peker
- Biochemistry, University of Cologne, Cologne, Germany
- CECAD, University of Cologne, Cologne, Germany
| | - Christine Zarges
- Biochemistry, University of Cologne, Cologne, Germany
- CECAD, University of Cologne, Cologne, Germany
| | - Janina Faust
- Cell Biology, University of Kaiserslautern, Kaiserslautern, Germany
| | - Zuzana Storchova
- Molecular Genetics, University of Kaiserslautern, Kaiserslautern, Germany
| | - Markus Räschle
- Molecular Genetics, University of Kaiserslautern, Kaiserslautern, Germany
| | - Jan Riemer
- Biochemistry, University of Cologne, Cologne, Germany
- CECAD, University of Cologne, Cologne, Germany
| | | |
Collapse
|
8
|
Godbold GD, Hewitt FC, Kappell AD, Scholz MB, Agar SL, Treangen TJ, Ternus KL, Sandbrink JB, Koblentz GD. Improved understanding of biorisk for research involving microbial modification using annotated sequences of concern. Front Bioeng Biotechnol 2023; 11:1124100. [PMID: 37180048 PMCID: PMC10167326 DOI: 10.3389/fbioe.2023.1124100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 04/11/2023] [Indexed: 05/15/2023] Open
Abstract
Regulation of research on microbes that cause disease in humans has historically been focused on taxonomic lists of 'bad bugs'. However, given our increased knowledge of these pathogens through inexpensive genome sequencing, 5 decades of research in microbial pathogenesis, and the burgeoning capacity of synthetic biologists, the limitations of this approach are apparent. With heightened scientific and public attention focused on biosafety and biosecurity, and an ongoing review by US authorities of dual-use research oversight, this article proposes the incorporation of sequences of concern (SoCs) into the biorisk management regime governing genetic engineering of pathogens. SoCs enable pathogenesis in all microbes infecting hosts that are 'of concern' to human civilization. Here we review the functions of SoCs (FunSoCs) and discuss how they might bring clarity to potentially problematic research outcomes involving infectious agents. We believe that annotation of SoCs with FunSoCs has the potential to improve the likelihood that dual use research of concern is recognized by both scientists and regulators before it occurs.
Collapse
Affiliation(s)
| | | | | | | | - Stacy L. Agar
- Signature Science, LLC, Charlottesville, VA, United States
| | - Todd J. Treangen
- Department of Computer Science, Rice University, Houston, TX, United States
| | | | - Jonas B. Sandbrink
- Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Gregory D. Koblentz
- Schar School of Policy and Government, George Mason University, Arlington, VA, United States
| |
Collapse
|
9
|
Abstract
SARS-CoV-2, the virus responsible for the COVID-19 pandemic, has been associated with substantial global morbidity and mortality. Despite a tropism that is largely confined to the airways, COVID-19 is associated with multiorgan dysfunction and long-term cognitive pathologies. A major driver of this biology stems from the combined effects of virus-mediated interference with the host antiviral defences in infected cells and the sensing of pathogen-associated material by bystander cells. Such a dynamic results in delayed induction of type I and III interferons (IFN-I and IFN-III) at the site of infection, but systemic IFN-I and IFN-III priming in distal organs and barrier epithelial surfaces, respectively. In this Review, we examine the relationship between SARS-CoV-2 biology and the cellular response to infection, detailing how antagonism and dysregulation of host innate immune defences contribute to disease severity of COVID-19.
Collapse
Affiliation(s)
- Judith M Minkoff
- Department of Microbiology, New York University Langone Health, New York, NY, USA
| | - Benjamin tenOever
- Department of Microbiology, New York University Langone Health, New York, NY, USA.
| |
Collapse
|
10
|
Jin X, Sun X, Chai Y, Bai Y, Li Y, Hao T, Qi J, Song H, Wong CCL, Gao GF. Structural characterization of SARS-CoV-2 dimeric ORF9b reveals potential fold-switching trigger mechanism. SCIENCE CHINA. LIFE SCIENCES 2023; 66:152-164. [PMID: 36184694 PMCID: PMC9527070 DOI: 10.1007/s11427-022-2168-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 07/20/2022] [Indexed: 11/06/2022]
Abstract
The constant emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants indicates the evolution and adaptation of the virus. Enhanced innate immune evasion through increased expression of viral antagonist proteins, including ORF9b, contributes to the improved transmission of the Alpha variant; hence, more attention should be paid to these viral proteins. ORF9b is an accessory protein that suppresses innate immunity via a monomer conformation by binding to Tom70. Here, we solved the dimeric structure of SARS-CoV-2 ORF9b with a long hydrophobic tunnel containing a lipid molecule that is crucial for the dimeric conformation and determined the specific lipid ligands as monoglycerides by conducting a liquid chromatography with tandem mass spectrometry analysis, suggesting an important role in the viral life cycle. Notably, a long intertwined loop accessible for host factor binding was observed in the structure. Eight phosphorylated residues in ORF9b were identified, and residues S50 and S53 were found to contribute to the stabilization of dimeric ORF9b. Additionally, we proposed a model of multifunctional ORF9b with a distinct conformation, suggesting that ORF9b is a fold-switching protein, while both lipids and phosphorylation contribute to the switching. Specifically, the ORF9b monomer interacts with Tom70 to suppress the innate immune response, whereas the ORF9b dimer binds to the membrane involving mature virion assembly. Our results provide a better understanding of the multiple functions of ORF9b.
Collapse
Affiliation(s)
- Xiyue Jin
- grid.59053.3a0000000121679639School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230027 China ,grid.9227.e0000000119573309CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101 China
| | - Xue Sun
- grid.11135.370000 0001 2256 9319Peking University First Hospital, Peking University, Beijing, 100034 China ,grid.11135.370000 0001 2256 9319Center for Precision Medicine Multi-Omics Research, Peking University Health Science Center, Peking University, Beijing, 100191 China
| | - Yan Chai
- grid.9227.e0000000119573309CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101 China
| | - Yu Bai
- grid.9227.e0000000119573309CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101 China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Ying Li
- grid.9227.e0000000119573309CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101 China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Tianjiao Hao
- grid.9227.e0000000119573309CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101 China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Jianxun Qi
- grid.9227.e0000000119573309CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101 China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Hao Song
- grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, 100049 China ,grid.9227.e0000000119573309Research Network of Immunity and Health (RNIH), Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, 100101 China
| | - Catherine C. L. Wong
- grid.11135.370000 0001 2256 9319Peking University First Hospital, Peking University, Beijing, 100034 China ,grid.11135.370000 0001 2256 9319Center for Precision Medicine Multi-Omics Research, Peking University Health Science Center, Peking University, Beijing, 100191 China ,grid.11135.370000 0001 2256 9319Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871 China ,grid.11135.370000 0001 2256 9319School of Basic Medical Sciences, Peking University Health Science Center, Peking University, Beijing, 100191 China
| | - George F. Gao
- grid.59053.3a0000000121679639School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230027 China ,grid.9227.e0000000119573309CAS Key Laboratory of Pathogen Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101 China ,grid.410726.60000 0004 1797 8419University of Chinese Academy of Sciences, Beijing, 100049 China ,grid.9227.e0000000119573309Research Network of Immunity and Health (RNIH), Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, 100101 China
| |
Collapse
|
11
|
Montes de Oca-B P. Evidence of mitochondria origin of SARS-CoV-2 double-membrane vesicles: a review. F1000Res 2022; 10:1009. [PMID: 38827572 PMCID: PMC11140301 DOI: 10.12688/f1000research.73170.2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/26/2022] [Indexed: 06/04/2024] Open
Abstract
Coronavirus Disease-19 (COVID-19) pandemic is caused by the coronavirus SARS-CoV-2 that has infected in a year more than 200 million people and has killed almost 4.5 million people worldwide. This infection affects mainly certain groups of people that have high susceptibility to present severe COVID-19 due to comorbidities. Moreover, the long-COVID-19 comprises a series of symptoms that may remain in some patients for months after infection that further compromises health of individuals. Therefore, this pandemic poses a serious emergency worldwide. Thus, since this pandemic is profoundly affecting economic and social life of societies, a deeper understanding of SARS-CoV-2 infection cycle could help to envisage novel therapeutic alternatives that limit or stop COVID-19. Several recent findings have unexpectedly found that mitochondria play a critical role in SARS-CoV-2 cell infection. Indeed, it has been suggested that this organelle could be the origin of its replication niches, the double membrane vesicles (DMV), as its been observed with another virus. In this regard, mitochondria derived vesicles (MDV), involved in mitochondria quality control, were discovered more than 10 years ago and interestingly there is a population characterized by a double membrane. MDV shedding is induced by mitochondrial stress and it has a fast assembly dynamic, reason that perhaps has precluded their identification in electron microscopy or tomography studies. These and other features of MDV together with recent SARS-CoV-2 protein interactome with the host and other findings linking SARS-CoV-2 to mitochondria, support that these vesicles are the precursors of SARS-CoV-2 induced DMV. In this work, the celular, molecular, phenotypical and biochemical evidence that supports this hypothesis is reviewed and integrated into the current model of SARS-CoV-2 cell infection. In this scheme, some relevant questions are raised as pending topics for research that would help in the near future to test this hypothesis. The intention (abstract truncated).
Collapse
Affiliation(s)
- Pavel Montes de Oca-B
- Neurociencia Cognitiva, Instituto de Fisiologia-UNAM, CDMX, CDMX, 04510, Mexico
- Unidad de Neurobiologia Dinamica, Instituto Nacional de Neurologia y Neurocirugia, CDMX, CDMX, 14269, Mexico
| |
Collapse
|
12
|
Ayinde KS, Pinheiro GM, Ramos CH. Binding of SARS-CoV-2 protein ORF9b to mitochondrial translocase TOM70 prevents its interaction with chaperone HSP90. Biochimie 2022; 200:99-106. [PMID: 35643212 PMCID: PMC9132681 DOI: 10.1016/j.biochi.2022.05.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Revised: 05/21/2022] [Accepted: 05/23/2022] [Indexed: 01/17/2023]
Abstract
The emergence of the COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), remains a great threat to global health. ORF9b, an important accessory protein of SARS-CoV-2, plays a critical role in the viral host interaction, targeting TOM70, a member of the mitochondrial translocase of the outer membrane complex. The assembly between ORF9b and TOM70 is implicated in disrupting mitochondrial antiviral signaling, leading to immune evasion. We describe the expression, purification, and characterization of ORF9b alone or coexpressed with the cytosolic domain of human TOM70 in E. coli. ORF9b has 97 residues and was purified as a homodimer with an molecular mass of 22 kDa as determined by SEC-MALS. Circular dichroism experiments showed that Orf9b alone exhibits a random conformation. The ORF9b-TOM70 complex characterized by CD and differential scanning calorimetry showed that the complex is folded and more thermally stable than free TOM70, indicating strong binding. Importantly, protein-protein interaction assays demonstrated that full-length human Hsp90 is capable of binding to free TOM70 but not to the ORF9b-TOM70 complex. To narrow down the nature of this inhibition, the isolated C-terminal domain of Hsp90 was also tested. These results were used to build a model of the mechanism of inhibition, in which ORF9b efficiently targets two sites of interaction between TOM70 and Hsp90. The findings showed that ORF9b complexed with TOM70 prevents the interaction with Hsp90, and this is one major explanation for SARS-CoV-2 evasion of host innate immunity via the inhibition of the interferon activation pathway.
Collapse
Affiliation(s)
- Kehinde S. Ayinde
- Institute of Chemistry, University of Campinas UNICAMP, 13083-970, Campinas, SP, Brazil,Institute of Biology, University of Campinas (UNICAMP), SP, Brazil
| | - Glaucia M.S. Pinheiro
- Institute of Chemistry, University of Campinas UNICAMP, 13083-970, Campinas, SP, Brazil
| | - Carlos H.I. Ramos
- Institute of Chemistry, University of Campinas UNICAMP, 13083-970, Campinas, SP, Brazil,Corresponding author
| |
Collapse
|
13
|
Chen J, Lu Z, Yang X, Zhou Y, Gao J, Zhang S, Huang S, Cai J, Yu J, Zhao W, Zhang B. Severe Acute Respiratory Syndrome Coronavirus 2 ORF8 Protein Inhibits Type I Interferon Production by Targeting HSP90B1 Signaling. Front Cell Infect Microbiol 2022; 12:899546. [PMID: 35677655 PMCID: PMC9168264 DOI: 10.3389/fcimb.2022.899546] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 04/08/2022] [Indexed: 12/14/2022] Open
Abstract
Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a global pandemic that has currently infected over 430 million individuals worldwide. With the variant strains of SARS-CoV-2 emerging, a region of high mutation rates in ORF8 was identified during the early pandemic, which resulted in a mutation from leucine (L) to serine (S) at amino acid 84. A typical feature of ORF8 is the immune evasion by suppressing interferon response; however, the mechanisms by which the two variants of ORF8 antagonize the type I interferon (IFN-I) pathway have not yet been clearly investigated. Here, we reported that SARS-CoV-2 ORF8L and ORF8S with no difference inhibit the production of IFN-β, MDA5, RIG-I, ISG15, ISG56, IRF3, and other IFN-related genes induced by poly(I:C). In addition, both ORF8L and ORF8S proteins were found to suppress the nuclear translocation of IRF3. Mechanistically, the SARS-CoV-2 ORF8 protein interacts with HSP90B1, which was later investigated to induce the production of IFN-β and IRF3. Taken together, these results indicate that SARS-CoV-2 ORF8 antagonizes the RIG-I/MDA-5 signaling pathway by targeting HSP90B1, which subsequently exhibits an inhibitory effect on the production of IFN-I. These functions appeared not to be influenced by the genotypes of ORF8L and ORF8S. Our study provides an explanation for the antiviral immune suppression of SARS-CoV-2 and suggests implications for the pathogenic mechanism and treatment of COVID-19.
Collapse
Affiliation(s)
- Jiayi Chen
- BSL-3 Laboratory (Guangdong), Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, China
| | - Zixin Lu
- BSL-3 Laboratory (Guangdong), Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, China
| | - Xiuwen Yang
- BSL-3 Laboratory (Guangdong), Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, China
| | - Yezhen Zhou
- BSL-3 Laboratory (Guangdong), Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, China
| | - Jing Gao
- BSL-3 Laboratory (Guangdong), Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, China
| | - Shihao Zhang
- BSL-3 Laboratory (Guangdong), Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, China
| | - Shan Huang
- Department of Epidemiology, School of Public Health, Southern Medical University, Guangzhou, China
| | - Jintai Cai
- BSL-3 Laboratory (Guangdong), Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, China
| | - Jianhai Yu
- BSL-3 Laboratory (Guangdong), Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, China
| | - Wei Zhao
- BSL-3 Laboratory (Guangdong), Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, China
- *Correspondence: Bao Zhang, ; Wei Zhao,
| | - Bao Zhang
- BSL-3 Laboratory (Guangdong), Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, China
- *Correspondence: Bao Zhang, ; Wei Zhao,
| |
Collapse
|
14
|
Gusev E, Sarapultsev A, Solomatina L, Chereshnev V. SARS-CoV-2-Specific Immune Response and the Pathogenesis of COVID-19. Int J Mol Sci 2022; 23:1716. [PMID: 35163638 PMCID: PMC8835786 DOI: 10.3390/ijms23031716] [Citation(s) in RCA: 79] [Impact Index Per Article: 39.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 01/31/2022] [Accepted: 02/01/2022] [Indexed: 12/13/2022] Open
Abstract
The review aims to consolidate research findings on the molecular mechanisms and virulence and pathogenicity characteristics of coronavirus disease (COVID-19) causative agent, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and their relevance to four typical stages in the development of acute viral infection. These four stages are invasion; primary blockade of antiviral innate immunity; engagement of the virus's protection mechanisms against the factors of adaptive immunity; and acute, long-term complications of COVID-19. The invasion stage entails the recognition of the spike protein (S) of SARS-CoV-2 target cell receptors, namely, the main receptor (angiotensin-converting enzyme 2, ACE2), its coreceptors, and potential alternative receptors. The presence of a diverse repertoire of receptors allows SARS-CoV-2 to infect various types of cells, including those not expressing ACE2. During the second stage, the majority of the polyfunctional structural, non-structural, and extra proteins SARS-CoV-2 synthesizes in infected cells are involved in the primary blockage of antiviral innate immunity. A high degree of redundancy and systemic action characterizing these pathogenic factors allows SARS-CoV-2 to overcome antiviral mechanisms at the initial stages of invasion. The third stage includes passive and active protection of the virus from factors of adaptive immunity, overcoming of the barrier function at the focus of inflammation, and generalization of SARS-CoV-2 in the body. The fourth stage is associated with the deployment of variants of acute and long-term complications of COVID-19. SARS-CoV-2's ability to induce autoimmune and autoinflammatory pathways of tissue invasion and development of both immunosuppressive and hyperergic mechanisms of systemic inflammation is critical at this stage of infection.
Collapse
Affiliation(s)
- Evgenii Gusev
- Laboratory of Immunology of Inflammation, Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Science, 620049 Ekaterinburg, Russia
| | - Alexey Sarapultsev
- Laboratory of Immunology of Inflammation, Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Science, 620049 Ekaterinburg, Russia
- Russian-Chinese Education and Research Center of System Pathology, South Ural State University, 454080 Chelyabinsk, Russia
| | - Liliya Solomatina
- Laboratory of Immunology of Inflammation, Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Science, 620049 Ekaterinburg, Russia
| | - Valeriy Chereshnev
- Laboratory of Immunology of Inflammation, Institute of Immunology and Physiology, Ural Branch of the Russian Academy of Science, 620049 Ekaterinburg, Russia
| |
Collapse
|
15
|
Pizzato M, Baraldi C, Boscato Sopetto G, Finozzi D, Gentile C, Gentile MD, Marconi R, Paladino D, Raoss A, Riedmiller I, Ur Rehman H, Santini A, Succetti V, Volpini L. SARS-CoV-2 and the Host Cell: A Tale of Interactions. FRONTIERS IN VIROLOGY 2022. [DOI: 10.3389/fviro.2021.815388] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The ability of a virus to spread between individuals, its replication capacity and the clinical course of the infection are macroscopic consequences of a multifaceted molecular interaction of viral components with the host cell. The heavy impact of COVID-19 on the world population, economics and sanitary systems calls for therapeutic and prophylactic solutions that require a deep characterization of the interactions occurring between virus and host cells. Unveiling how SARS-CoV-2 engages with host factors throughout its life cycle is therefore fundamental to understand the pathogenic mechanisms underlying the viral infection and to design antiviral therapies and prophylactic strategies. Two years into the SARS-CoV-2 pandemic, this review provides an overview of the interplay between SARS-CoV-2 and the host cell, with focus on the machinery and compartments pivotal for virus replication and the antiviral cellular response. Starting with the interaction with the cell surface, following the virus replicative cycle through the characterization of the entry pathways, the survival and replication in the cytoplasm, to the mechanisms of egress from the infected cell, this review unravels the complex network of interactions between SARS-CoV-2 and the host cell, highlighting the knowledge that has the potential to set the basis for the development of innovative antiviral strategies.
Collapse
|
16
|
Montenegro YHA, Zanatta G, Quincozes-Santos A, Leipnitz G. TOM70 in Glial Cells as a Potential Target for Treatment of COVID-19. Front Cell Neurosci 2021; 15:811376. [PMID: 35002631 PMCID: PMC8740195 DOI: 10.3389/fncel.2021.811376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 12/07/2021] [Indexed: 11/24/2022] Open
Affiliation(s)
| | - Geancarlo Zanatta
- Programa de Pós-Graduação em Bioquímica, Universidade Federal do Ceará, Fortaleza, Brazil
- Departamento de Física, Universidade Federal do Ceará, Fortaleza, Brazil
| | - André Quincozes-Santos
- Programa de Pós-Graduação em Neurociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Guilhian Leipnitz
- Programa de Pós-Graduação em Neurociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| |
Collapse
|
17
|
The N-terminal Region of Middle East Respiratory Syndrome Coronavirus Accessory Protein 8b is Essential for Enhanced Virulence of an Attenuated Murine Coronavirus. J Virol 2021; 96:e0184221. [PMID: 34817197 PMCID: PMC8826903 DOI: 10.1128/jvi.01842-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Middle East respiratory syndrome coronavirus (MERS-CoV) is a beta coronavirus that emerged in 2012, causing severe pneumonia and renal failure. MERS-CoV encodes five accessory proteins. Some of them have been shown to interfere with host antiviral immune response. However, the roles of protein 8b in innate immunity and viral virulence was rarely studied. Here, we introduced individual MERS-CoV accessory protein genes into the genome of an attenuated murine coronavirus (Mouse hepatitis virus, MHV), respectively, and found accessory protein 8b could enhance viral replication in vivo and in vitro and increase the lethality of infected mice. RNA-seq analysis revealed that protein 8b could significantly inhibit type I interferon production (IFN-I) and innate immune response in mice infected with MHV expressing protein 8b. We also found that MERS-CoV protein 8b could initiate from multiple internal methionine sites and at least three protein variants were identified. Residues 1-23 of protein 8b was demonstrated to be responsible for increased virulence in vivo. In addition, the inhibitory effect on IFN-I of protein 8b might not contribute to its virulence enhancement as aa1-23 deletion did not affect IFN-I production in vitro and in vivo. Next, we also found that protein 8b was localized to the endoplasmic reticulum (ER)/Golgi membrane in infected cells, which was disrupted by C-terminal region aa 88-112 deletion. This study will provide new insight into the pathogenesis of MERS-CoV infection. IMPORTANCE Multiple coronaviruses (CoV) cause severe respiratory infections and become global public health threats such as SARS-CoV, MERS-CoV, and SARS-CoV-2. Each coronavirus contains different numbers of accessory proteins which show high variability among different CoVs. Accessory proteins are demonstrated to play essential roles in pathogenesis of CoVs. MERS-CoV contains 5 accessory proteins (protein 3, 4a, 4b, 5, 8b), and deletion of all four accessory proteins (protein 3, 4a, 4b, 5), significantly affects MERS-CoV replication and pathogenesis. However, whether ORF8b also regulates MERS-CoV infection is unknown. Here, we constructed mouse hepatitis virus (MHV) recombinant virus expressing MERS-CoV protein 8b and demonstrated protein 8b could significantly enhance the virulence of MHV, which is mediated by N-terminal domain of protein 8b. This study will shed light on the understanding of pathogenesis of MERS-CoV infection.
Collapse
|