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Bermudez-Santana CI, Gallego-Gómez JC. Toward a Categorization of Virus-ncRNA Interactions in the World of RNA to Disentangle the Tiny Secrets of Dengue Virus. Viruses 2024; 16:804. [PMID: 38793685 PMCID: PMC11125801 DOI: 10.3390/v16050804] [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: 04/03/2024] [Revised: 05/14/2024] [Accepted: 05/15/2024] [Indexed: 05/26/2024] Open
Abstract
In recent years, the function of noncoding RNAs (ncRNAs) as regulatory molecules of cell physiology has begun to be better understood. Advances in viral molecular biology have shown that host ncRNAs, cellular factors, and virus-derived ncRNAs and their interplay are strongly disturbed during viral infections. Nevertheless, the folding of RNA virus genomes has also been identified as a critical factor in regulating canonical and non-canonical functions. Due to the influence of host ncRNAs and the structure of RNA viral genomes, complex molecular and cellular processes in infections are modulated. We propose three main categories to organize the current information about RNA-RNA interactions in some well-known human viruses. The first category shows examples of host ncRNAs associated with the immune response triggered in viral infections. Even though miRNAs introduce a standpoint, they are briefly presented to keep researchers moving forward in uncovering other RNAs. The second category outlines interactions between virus-host ncRNAs, while the third describes how the structure of the RNA viral genome serves as a scaffold for processing virus-derived RNAs. Our grouping may provide a comprehensive framework to classify ncRNA-host-cell interactions for emerging viruses and diseases. In this sense, we introduced them to organize DENV-host-cell interactions.
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Affiliation(s)
- Clara Isabel Bermudez-Santana
- Computational and theoretical RNomics Group, Center of Excellence in Scientific Computing, Universidad Nacional de Colombia, Bogotá 111321, Colombia
| | - Juan Carlos Gallego-Gómez
- Grupo de Medicina de Traslación, Facultad de Medicina, Universidad de Antioquia, Medellín 050010, Colombia;
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2
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Nishiyama S, Hirano M, Muto M, Kambara M, Ito N, Kobayashi S, Kariwa H, Yoshii K. Y-shaped RNA Secondary Structure of a Noncoding Region in the Genomic RNA of Tick-Borne Encephalitis Virus Affects Pathogenicity. Microbiol Immunol 2022; 66:234-237. [PMID: 35194811 DOI: 10.1111/1348-0421.12971] [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: 12/30/2021] [Revised: 02/14/2022] [Accepted: 02/18/2022] [Indexed: 11/28/2022]
Abstract
Tick-borne encephalitis virus (TBEV) is a zoonotic virus that causes encephalitis in humans. Various deletions have been reported in a variable region of the 3' untranslated region of the TBEV genome. In this study, we analyzed the role of a Y-shaped secondary structure in the pathogenicity of TBEV by using reverse genetics. Deletion of the structure increased the mortality rate of virus-infected mice but did not affect virus multiplication in cultured cells and organs. Our results indicated that the secondary structure is involved in the regulation of TBEV pathogenesis. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Shoko Nishiyama
- Laboratory of Zoonotic Disease, Joint Department of Veterinary Medicine, Faculty of Applied Biosciences, Gifu University, Gifu, Japan
| | - Minato Hirano
- Laboratory of Public Health, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan.,National Research Center for the Control and Prevention of Infectious Diseases, Nagasaki University, Nagasaki, Japan
| | - Memi Muto
- Laboratory of Public Health, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Mao Kambara
- Laboratory of Public Health, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Naoto Ito
- Laboratory of Zoonotic Disease, Joint Department of Veterinary Medicine, Faculty of Applied Biosciences, Gifu University, Gifu, Japan
| | - Shintaro Kobayashi
- Laboratory of Public Health, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Hiroaki Kariwa
- Laboratory of Public Health, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan
| | - Kentaro Yoshii
- Laboratory of Public Health, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan.,National Research Center for the Control and Prevention of Infectious Diseases, Nagasaki University, Nagasaki, Japan
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3
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Zhang S, Sun R, Perdoncini Carvalho C, Han J, Zheng L, Qu F. Replication-Dependent Biogenesis of Turnip Crinkle Virus Long Noncoding RNAs. J Virol 2021; 95:e0016921. [PMID: 34160262 PMCID: PMC8387050 DOI: 10.1128/jvi.00169-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Accepted: 06/14/2021] [Indexed: 12/24/2022] Open
Abstract
Long noncoding RNAs (lncRNAs) of virus origin accumulate in cells infected by many positive-strand (+) RNA viruses to bolster viral infectivity. Their biogenesis mostly utilizes exoribonucleases of host cells that degrade viral genomic or subgenomic RNAs in the 5'-to-3' direction until being stalled by well-defined RNA structures. Here, we report a viral lncRNA that is produced by a novel replication-dependent mechanism. This lncRNA corresponds to the last 283 nucleotides of the turnip crinkle virus (TCV) genome and hence is designated tiny TCV subgenomic RNA (ttsgR). ttsgR accumulated to high levels in TCV-infected Nicotiana benthamiana cells when the TCV-encoded RNA-dependent RNA polymerase (RdRp), also known as p88, was overexpressed. Both (+) and (-) strand forms of ttsgR were produced in a manner dependent on the RdRp functionality. Strikingly, templates as short as ttsgR itself were sufficient to program ttsgR amplification, as long as the TCV-encoded replication proteins p28 and p88 were provided in trans. Consistent with its replicational origin, ttsgR accumulation required a 5' terminal carmovirus consensus sequence (CCS), a sequence motif shared by genomic and subgenomic RNAs of many viruses phylogenetically related to TCV. More importantly, introducing a new CCS motif elsewhere in the TCV genome was alone sufficient to cause the emergence of another lncRNA. Finally, abolishing ttsgR by mutating its 5' CCS gave rise to a TCV mutant that failed to compete with wild-type TCV in Arabidopsis. Collectively, our results unveil a replication-dependent mechanism for the biogenesis of viral lncRNAs, thus suggesting that multiple mechanisms, individually or in combination, may be responsible for viral lncRNA production. IMPORTANCE Many positive-strand (+) RNA viruses produce long noncoding RNAs (lncRNAs) during the process of cellular infections and mobilize these lncRNAs to counteract antiviral defenses, as well as coordinate the translation of viral proteins. Most viral lncRNAs arise from 5'-to-3' degradation of longer viral RNAs being stalled at stable secondary structures. Here, we report a viral lncRNA that is produced by the replication machinery of turnip crinkle virus (TCV). This lncRNA, designated ttsgR, shares the terminal characteristics with TCV genomic and subgenomic RNAs and overaccumulates in the presence of moderately overexpressed TCV RNA-dependent RNA polymerase (RdRp). Furthermore, templates that are of similar sizes as ttsgR are readily replicated by TCV replication proteins (p28 and RdRp) provided from nonviral sources. In summary, this study establishes an approach for uncovering low abundance viral lncRNAs, and characterizes a replicating TCV lncRNA. Similar investigations on human-pathogenic (+) RNA viruses could yield novel therapeutic targets.
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Affiliation(s)
- Shaoyan Zhang
- Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio, USA
| | - Rong Sun
- Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio, USA
| | - Camila Perdoncini Carvalho
- Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio, USA
| | - Junping Han
- Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio, USA
| | - Limin Zheng
- Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio, USA
| | - Feng Qu
- Department of Plant Pathology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, Ohio, USA
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4
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Mwaliko C, Nyaruaba R, Zhao L, Atoni E, Karungu S, Mwau M, Lavillette D, Xia H, Yuan Z. Zika virus pathogenesis and current therapeutic advances. Pathog Glob Health 2021; 115:21-39. [PMID: 33191867 PMCID: PMC7850325 DOI: 10.1080/20477724.2020.1845005] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Zika virus (ZIKV) is an emerging arthropod-borne flavivirus that, upon infection, results in teratogenic effects and neurological disorders. ZIKV infections pose serious global public health concerns, prompting scientists to increase research on antivirals and vaccines against the virus. These efforts are still ongoing as the pathogenesis and immune evasion mechanisms of ZIKV have not yet been fully elaborated. Currently, no specific vaccines or drugs have been approved for ZIKV; however, some are undergoing clinical trials. Notably, several strategies have been used to develop antivirals, including drugs that target viral and host proteins. Additionally, drug repurposing is preferred since it is less costly and takes less time than other strategies because the drugs used have already been approved for human use. Likewise, different platforms have been evaluated for the design of vaccines, including DNA, mRNA, peptide, protein, viral vectors, virus-like particles (VLPSs), inactivated-virus, and live-attenuated virus vaccines. These vaccines have been shown to induce specific humoral and cellular immune responses and reduce viremia and viral RNA both in vitro and in vivo. Importantly, most of these vaccines have entered clinical trials. Understanding the viral disease mechanism will provide better strategies for developing therapeutic agents against ZIKV. This review provides a comprehensive summary of the viral pathogenesis of ZIKV and current advancements in the development of vaccines and drugs against this virus.
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Affiliation(s)
- Caroline Mwaliko
- Key Laboratory of Special Pathogens and Biosafety, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China,International College, University of Chinese Academy of Sciences, Beijing, China,Microbiology, Sino-Africa Joint Research Center, Nairobi, Kenya
| | - Raphael Nyaruaba
- Key Laboratory of Special Pathogens and Biosafety, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China,International College, University of Chinese Academy of Sciences, Beijing, China,Microbiology, Sino-Africa Joint Research Center, Nairobi, Kenya
| | - Lu Zhao
- Key Laboratory of Special Pathogens and Biosafety, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China,International College, University of Chinese Academy of Sciences, Beijing, China
| | - Evans Atoni
- Key Laboratory of Special Pathogens and Biosafety, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China,International College, University of Chinese Academy of Sciences, Beijing, China,Microbiology, Sino-Africa Joint Research Center, Nairobi, Kenya
| | - Samuel Karungu
- Key Laboratory of Special Pathogens and Biosafety, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China,International College, University of Chinese Academy of Sciences, Beijing, China,Microbiology, Sino-Africa Joint Research Center, Nairobi, Kenya
| | - Matilu Mwau
- Center for Infectious and Parasitic Diseases Control Research, Kenya Medical Research Institute, Nairobi, Kenya
| | - Dimitri Lavillette
- CAS Key Laboratory of Molecular Virology & Immunology, Institut Pasteur of Shanghai, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Han Xia
- Key Laboratory of Special Pathogens and Biosafety, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China,CONTACT Han Xia ; Zhiming Yuan Key Laboratory of Special Pathogens and Biosafety, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Zhiming Yuan
- Key Laboratory of Special Pathogens and Biosafety, Center for Biosafety Mega-Science, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
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5
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Szucs MJ, Nichols PJ, Jones RA, Vicens Q, Kieft JS. A New Subclass of Exoribonuclease-Resistant RNA Found in Multiple Genera of Flaviviridae. mBio 2020; 11:mBio.02352-20. [PMID: 32994331 DOI: 10.1101/2020.06.26.172668] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023] Open
Abstract
Viruses have developed innovative strategies to exploit the cellular machinery and overcome the antiviral defenses of the host, often using specifically structured RNA elements. Examples are found in the Flavivirus genus (in the family Flaviviridae), where during flaviviral infection, pathogenic subgenomic flaviviral RNAs (sfRNAs) accumulate in the cell. These sfRNAs are formed when a host cell 5' to 3' exoribonuclease degrades the viral genomic RNA but is blocked by an exoribonuclease-resistant RNA structure (xrRNA) located in the viral genome's 3' untranslated region (UTR). Although known to exist in several Flaviviridae genera, the full distribution and diversity of xrRNAs in this family were unknown. Using the recently solved high-resolution structure of an xrRNA from the divergent flavivirus Tamana bat virus (TABV) as a reference, we used bioinformatic searches to identify xrRNAs in the remaining three genera of Flaviviridae: Pegivirus, Pestivirus, and Hepacivirus We biochemically and structurally characterized several examples, determining that they are genuine xrRNAs with a conserved fold. These new xrRNAs look superficially similar to the previously described xrRNAs but possess structural differences making them distinct from previous classes of xrRNAs. Overall, we have identified the presence of xrRNA in all four genera of Flaviviridae, but not in all species. Our findings thus require adjustments of previous xrRNA classification schemes and expand the previously known distribution of xrRNA in Flaviviridae.IMPORTANCE The members of the Flaviviridae comprise one of the largest families of positive-sense single-stranded RNA (+ssRNA) and are divided into the Flavivirus, Pestivirus, Pegivirus, and Hepacivirus genera. The genus Flavivirus contains many medically relevant viruses such as Zika virus, dengue virus, and Powassan virus. In these, a part of the RNA of the virus twists up into a distinct three-dimensional shape called an exoribonuclease-resistant RNA (xrRNA) that blocks the ability of the cell to "chew up" the viral RNA. Hence, part of the RNA of the virus remains intact, and this protected part is important for viral infection. These xrRNAs were known to occur in flaviviruses, but whether they existed in the other members of the family was not known. In this study, we identified a new subclass of xrRNA found not only in flaviviruses but also in the remaining three genera. The fact that these structured viral RNAs exist throughout the Flaviviridae family suggests they are important parts of the infection strategy of diverse pathogens, which could lead to new avenues of research.
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Affiliation(s)
- Matthew J Szucs
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado, USA
| | - Parker J Nichols
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado, USA
| | - Rachel A Jones
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado, USA
| | - Quentin Vicens
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado, USA
| | - Jeffrey S Kieft
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, Colorado, USA
- RNA BioScience Initiative, University of Colorado Denver School of Medicine, Aurora, Colorado, USA
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6
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Abstract
The members of the Flaviviridae comprise one of the largest families of positive-sense single-stranded RNA (+ssRNA) and are divided into the Flavivirus, Pestivirus, Pegivirus, and Hepacivirus genera. The genus Flavivirus contains many medically relevant viruses such as Zika virus, dengue virus, and Powassan virus. In these, a part of the RNA of the virus twists up into a distinct three-dimensional shape called an exoribonuclease-resistant RNA (xrRNA) that blocks the ability of the cell to “chew up” the viral RNA. Hence, part of the RNA of the virus remains intact, and this protected part is important for viral infection. These xrRNAs were known to occur in flaviviruses, but whether they existed in the other members of the family was not known. In this study, we identified a new subclass of xrRNA found not only in flaviviruses but also in the remaining three genera. The fact that these structured viral RNAs exist throughout the Flaviviridae family suggests they are important parts of the infection strategy of diverse pathogens, which could lead to new avenues of research. Viruses have developed innovative strategies to exploit the cellular machinery and overcome the antiviral defenses of the host, often using specifically structured RNA elements. Examples are found in the Flavivirus genus (in the family Flaviviridae), where during flaviviral infection, pathogenic subgenomic flaviviral RNAs (sfRNAs) accumulate in the cell. These sfRNAs are formed when a host cell 5′ to 3′ exoribonuclease degrades the viral genomic RNA but is blocked by an exoribonuclease-resistant RNA structure (xrRNA) located in the viral genome’s 3′ untranslated region (UTR). Although known to exist in several Flaviviridae genera, the full distribution and diversity of xrRNAs in this family were unknown. Using the recently solved high-resolution structure of an xrRNA from the divergent flavivirus Tamana bat virus (TABV) as a reference, we used bioinformatic searches to identify xrRNAs in the remaining three genera of Flaviviridae: Pegivirus, Pestivirus, and Hepacivirus. We biochemically and structurally characterized several examples, determining that they are genuine xrRNAs with a conserved fold. These new xrRNAs look superficially similar to the previously described xrRNAs but possess structural differences making them distinct from previous classes of xrRNAs. Overall, we have identified the presence of xrRNA in all four genera of Flaviviridae, but not in all species. Our findings thus require adjustments of previous xrRNA classification schemes and expand the previously known distribution of xrRNA in Flaviviridae.
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7
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Eiermann N, Haneke K, Sun Z, Stoecklin G, Ruggieri A. Dance with the Devil: Stress Granules and Signaling in Antiviral Responses. Viruses 2020; 12:v12090984. [PMID: 32899736 PMCID: PMC7552005 DOI: 10.3390/v12090984] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 08/31/2020] [Accepted: 08/31/2020] [Indexed: 02/07/2023] Open
Abstract
Cells have evolved highly specialized sentinels that detect viral infection and elicit an antiviral response. Among these, the stress-sensing protein kinase R, which is activated by double-stranded RNA, mediates suppression of the host translation machinery as a strategy to limit viral replication. Non-translating mRNAs rapidly condensate by phase separation into cytosolic stress granules, together with numerous RNA-binding proteins and components of signal transduction pathways. Growing evidence suggests that the integrated stress response, and stress granules in particular, contribute to antiviral defense. This review summarizes the current understanding of how stress and innate immune signaling act in concert to mount an effective response against virus infection, with a particular focus on the potential role of stress granules in the coordination of antiviral signaling cascades.
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Affiliation(s)
- Nina Eiermann
- Division of Biochemistry, Mannheim Institute for Innate Immunoscience (MI3), Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany; (N.E.); (K.H.); (G.S.)
| | - Katharina Haneke
- Division of Biochemistry, Mannheim Institute for Innate Immunoscience (MI3), Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany; (N.E.); (K.H.); (G.S.)
| | - Zhaozhi Sun
- Department of Infectious Diseases, Molecular Virology, Center for Integrative Infectious Disease Research (CIID), University of Heidelberg, 69120 Heidelberg, Germany;
| | - Georg Stoecklin
- Division of Biochemistry, Mannheim Institute for Innate Immunoscience (MI3), Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany; (N.E.); (K.H.); (G.S.)
| | - Alessia Ruggieri
- Department of Infectious Diseases, Molecular Virology, Center for Integrative Infectious Disease Research (CIID), University of Heidelberg, 69120 Heidelberg, Germany;
- Correspondence:
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Zika Virus Subgenomic Flavivirus RNA Generation Requires Cooperativity between Duplicated RNA Structures That Are Essential for Productive Infection in Human Cells. J Virol 2020; 94:JVI.00343-20. [PMID: 32581095 DOI: 10.1128/jvi.00343-20] [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: 02/27/2020] [Accepted: 06/16/2020] [Indexed: 12/15/2022] Open
Abstract
Zika virus (ZIKV) is an emerging flavivirus, mainly transmitted by mosquitoes, which represents a global health threat. A common feature of flavivirus-infected cells is the accumulation of viral noncoding subgenomic RNAs by partial degradation of the viral genome, known as sfRNAs, involved in immune evasion and pathogenesis. Although great effort is being made to understand the mechanism by which these sfRNAs function during infection, the picture of how they work is still incomplete. In this study, we developed new genetic tools to dissect the functions of ZIKV RNA structures for viral replication and sfRNA production in mosquito and human hosts. ZIKV infections mostly accumulate two kinds of sfRNAs, sfRNA1 and sfRNA2, by stalling genome degradation upstream of duplicated stem loops (SLI and SLII) of the viral 3' untranslated region (UTR). Although the two SLs share conserved sequences and structures, different functions have been found for ZIKV replication in human and mosquito cells. While both SLs are enhancers for viral infection in human cells, they play opposite roles in the mosquito host. The dissection of determinants for sfRNA formation indicated a strong cooperativity between SLI and SLII, supporting a high-order organization of this region of the 3' UTR. Using recombinant ZIKV with different SLI and SLII arrangements, which produce different types of sfRNAs or lack the ability to generate these molecules, revealed that at least one sfRNA was necessary for efficient infection and transmission in Aedes aegypti mosquitoes. Importantly, we demonstrate an absolute requirement of sfRNAs for ZIKV propagation in human cells. In this regard, viruses lacking sfRNAs, constructed by deletion of the region containing SLI and SLII, were able to infect human cells but the infection was rapidly cleared by antiviral responses. Our findings are unique for ZIKV, since in previous studies, other flaviviruses with deletions of analogous regions of the genome, including dengue and West Nile viruses, accumulated distinct species of sfRNAs and were infectious in human cells. We conclude that flaviviruses share common strategies for sfRNA generation, but they have evolved mechanisms to produce different kinds of these RNAs to accomplish virus-specific functions.IMPORTANCE Flaviviruses are important emerging and reemerging human pathogens. Understanding the molecular mechanisms for viral replication and evasion of host antiviral responses is relevant to development of control strategies. Flavivirus infections produce viral noncoding RNAs, known as sfRNAs, involved in viral replication and pathogenesis. In this study, we dissected molecular determinants for Zika virus sfRNA generation in the two natural hosts, human cells and mosquitoes. We found that two RNA structures of the viral 3' UTR operate in a cooperative manner to produce two species of sfRNAs and that the deletion of these elements has a profoundly different impact on viral replication in the two hosts. Generation of at least one sfRNA was necessary for efficient Zika virus infection of Aedes aegypti mosquitoes. Moreover, recombinant viruses with different 3' UTR arrangements revealed an essential role of sfRNAs for productive infection in human cells. In summary, we define molecular requirements for Zika virus sfRNA accumulation and provide new ideas of how flavivirus RNA structures have evolved to succeed in different hosts.
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9
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Zhang Y, Zhang Y, Liu Z, Cheng M, Ma J, Wang Y, Qin C, Fang X. Long non-coding subgenomic flavivirus RNAs have extended 3D structures and are flexible in solution. EMBO Rep 2019; 20:e47016. [PMID: 31502753 PMCID: PMC6832101 DOI: 10.15252/embr.201847016] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 08/14/2019] [Accepted: 08/21/2019] [Indexed: 01/05/2023] Open
Abstract
Most mosquito-borne flaviviruses, including Zika virus (ZIKV), Dengue virus (DENV), and West Nile virus (WNV), produce long non-coding subgenomic RNAs (sfRNAs) in infected cells that link to pathogenicity and immune evasion. Until now, the structural characterization of these lncRNAs remains limited. Here, we studied the 3D structures of individual and combined subdomains of sfRNAs, and visualized the accessible 3D conformational spaces of complete sfRNAs from DENV2, ZIKV, and WNV by small angle X-ray scattering (SAXS) and computational modeling. The individual xrRNA1s and xrRNA2s adopt similar structures in solution as the crystal structure of ZIKV xrRNA1, and all xrRNA1-2s form compact structures with reduced flexibility. While the DB12 of DENV2 is extended, the DB12s of ZIKV and WNV are compact due to the formation of intertwined double pseudoknots. All 3' stem-loops (3'SLs) share similar rod-like structures. Complete sfRNAs are extended and sample a large conformational space in solution. Our work not only provides structural insight into the function of flavivirus sfRNAs, but also highlights strategies of visualizing other lncRNAs in solution by SAXS and computational methods.
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Affiliation(s)
- Yupeng Zhang
- Beijing Advanced Innovation Center for Structural BiologySchool of Life SciencesTsinghua UniversityBeijingChina
| | - Yikan Zhang
- Beijing Advanced Innovation Center for Structural BiologySchool of Life SciencesTsinghua UniversityBeijingChina
| | - Zhong‐Yu Liu
- State Key Laboratory of Pathogen and BiosecurityBeijing Institute of Microbiology and EpidemiologyBeijingChina
- Guangzhou Eighth People's HospitalGuangzhou Medical UniversityGuangzhouChina
- School of Medicine (Shenzhen)Sun Yat‐sen UniversityGuangzhouChina
| | - Meng‐Li Cheng
- State Key Laboratory of Pathogen and BiosecurityBeijing Institute of Microbiology and EpidemiologyBeijingChina
| | - Junfeng Ma
- Beijing Advanced Innovation Center for Structural BiologySchool of Life SciencesTsinghua UniversityBeijingChina
| | - Yan Wang
- Beijing Advanced Innovation Center for Structural BiologySchool of Life SciencesTsinghua UniversityBeijingChina
| | - Cheng‐Feng Qin
- State Key Laboratory of Pathogen and BiosecurityBeijing Institute of Microbiology and EpidemiologyBeijingChina
| | - Xianyang Fang
- Beijing Advanced Innovation Center for Structural BiologySchool of Life SciencesTsinghua UniversityBeijingChina
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10
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RNase L Antiviral Activity Is Not a Critical Component of the Oas1b-Mediated Flavivirus Resistance Phenotype. J Virol 2019; 93:JVI.00946-19. [PMID: 31462564 DOI: 10.1128/jvi.00946-19] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 08/21/2019] [Indexed: 01/09/2023] Open
Abstract
In mice, resistance to central nervous system (CNS) disease induced by members of the genus Flavivirus is conferred by an allele of the 2'-5' oligoadenylate synthetase 1b gene that encodes the inactive full-length protein (Oas1b-FL). The susceptibility allele encodes a C-terminally truncated protein (Oas1b-tr). We show that the efficiency of neuron infection in the brains of resistant and susceptible mice is similar after an intracranial inoculation of two flaviviruses, but amplification of viral proteins and double-stranded RNA (dsRNA) is inhibited in infected neurons in resistant mouse brains at later times. Active OAS proteins detect cytoplasmic dsRNA and synthesize short 2'-5'-linked oligoadenylates (2'-5'A) that interact with the latent endonuclease RNase L, causing it to dimerize and cleave single-stranded RNAs. To evaluate the contribution of RNase L to the resistance phenotype in vivo, we created a line of resistant RNase L-/- mice. Evidence of RNase L activation in infected RNase L+/+ mice was indicated by higher levels of viral RNA in the brains of infected RNase L-/- mice. Activation of type I interferon (IFN) signaling was detected in both resistant and susceptible brains, but Oas1a and Oas1b mRNA levels were lower in RNase L+/+ mice of both types, suggesting that activated RNase L also has a proflaviviral effect. Inhibition of virus replication was robust in resistant RNase L-/- mice, indicating that activated RNase L is not a critical factor in mediating this phenotype.IMPORTANCE The mouse genome encodes a family of Oas proteins that synthesize 2'-5'A in response to dsRNA. 2'-5'A activates the endonuclease RNase L to cleave single-stranded viral and cellular RNAs. The inactive, full-length Oas1b protein confers flavivirus-specific disease resistance. Although similar numbers of neurons were infected in resistant and susceptible brains after an intracranial virus infection, viral components amplified only in susceptible brains at later times. A line of resistant RNase L-/- mice was used to evaluate the contribution of RNase L to the resistance phenotype in vivo Activation of RNase L antiviral activity by flavivirus infection was indicated by increased viral RNA levels in the brains of RNase L-/- mice. Oas1a and Oas1b mRNA levels were higher in infected RNase L-/- mice, indicating that activated RNase L also have a proflaviviral affect. However, the resistance phenotype was equally robust in RNase L-/- and RNase L+/+ mice.
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11
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Chen J, Ao L, Yang J. Long non-coding RNAs in diseases related to inflammation and immunity. ANNALS OF TRANSLATIONAL MEDICINE 2019; 7:494. [PMID: 31700930 DOI: 10.21037/atm.2019.08.37] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Long non-coding RNAs (lncRNAs) have been key regulators of gene expression in innate and adaptive immunity. Although lncRNAs have been reported to be associated with some diseases, its expression and function in diseases related to inflammation and immunity are still unknown. We reviewed how lncRNA regulated transcription and controlled the function and balance of the cells in the immune response. In addition, we discussed the impacts and challenges of lncRNAs on immunity in diseases.
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Affiliation(s)
- Jiao Chen
- Reproductive Medicine Center, Renmin Hospital of Wuhan University, Wuhan 430000, China.,Hubei Clinic Research Center for Assisted Reproductive Technology and Embryonic Development, Wuhan 430000, China
| | - Liangfei Ao
- Reproductive Medicine Center, Renmin Hospital of Wuhan University, Wuhan 430000, China.,Hubei Clinic Research Center for Assisted Reproductive Technology and Embryonic Development, Wuhan 430000, China
| | - Jing Yang
- Reproductive Medicine Center, Renmin Hospital of Wuhan University, Wuhan 430000, China.,Hubei Clinic Research Center for Assisted Reproductive Technology and Embryonic Development, Wuhan 430000, China
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12
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Hodge K, Kamkaew M, Pisitkun T, Chimnaronk S. Flavors of Flaviviral RNA Structure: towards an Integrated View of RNA Function from Translation through Encapsidation. Bioessays 2019; 41:e1900003. [PMID: 31210384 PMCID: PMC7161798 DOI: 10.1002/bies.201900003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 05/02/2019] [Indexed: 01/03/2023]
Abstract
For many viruses, RNA is the holder of genetic information and serves as the template for both replication and translation. While host and viral proteins play important roles in viral decision‐making, the extent to which viral RNA (vRNA) actively participates in translation and replication might be surprising. Here, the focus is on flaviviruses, which include common human scourges such as dengue, West Nile, and Zika viruses, from an RNA‐centric viewpoint. In reviewing more recent findings, an attempt is made to fill knowledge gaps and revisit some canonical views of vRNA structures involved in replication. In particular, alternative views are offered on the nature of the flaviviral promoter and genome cyclization, and the feasibility of refining in vitro‐derived models with modern RNA probing and sequencing methods is pointed out. By tracing vRNA structures from translation through encapsidation, a dynamic molecule closely involved in the self‐regulation of viral replication is revealed.
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Affiliation(s)
- Kenneth Hodge
- The Systems Biology Center, Research Affairs, Faculty of Medicine, Chulalongkorn University, 1873 Rama 4 Road, Pathumwan, Bangkok, 10330, Thailand
| | - Maliwan Kamkaew
- Laboratory of RNA Biology, Institute of Molecular Biosciences, Mahidol University, Salaya Campus, Nakhon Pathom, 73170, Thailand
| | - Trairak Pisitkun
- The Systems Biology Center, Research Affairs, Faculty of Medicine, Chulalongkorn University, 1873 Rama 4 Road, Pathumwan, Bangkok, 10330, Thailand
| | - Sarin Chimnaronk
- Laboratory of RNA Biology, Institute of Molecular Biosciences, Mahidol University, Salaya Campus, Nakhon Pathom, 73170, Thailand
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13
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Mazeaud C, Freppel W, Chatel-Chaix L. The Multiples Fates of the Flavivirus RNA Genome During Pathogenesis. Front Genet 2018. [PMID: 30564270 DOI: 10.3389/fgene.2018.00595/full] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/26/2023] Open
Abstract
The Flavivirus genus comprises many viruses (including dengue, Zika, West Nile and yellow fever viruses) which constitute important public health concerns worldwide. For several of these pathogens, neither antivirals nor vaccines are currently available. In addition to this unmet medical need, flaviviruses are of particular interest since they constitute an excellent model for the study of spatiotemporal regulation of RNA metabolism. Indeed, with no DNA intermediate or nuclear step, the flaviviral life cycle entirely relies on the cytoplasmic fate of a single RNA species, namely the genomic viral RNA (vRNA) which contains all the genetic information necessary for optimal viral replication. From a single open reading frame, the vRNA encodes a polyprotein which is processed to generate the mature viral proteins. In addition to coding for the viral polyprotein, the vRNA serves as a template for RNA synthesis and is also selectively packaged into newly assembled viral particles. Notably, vRNA translation, replication and encapsidation must be tightly coordinated in time and space via a fine-tuned equilibrium as these processes cannot occur simultaneously and hence, are mutually exclusive. As such, these dynamic processes involve several vRNA secondary and tertiary structures as well as RNA modifications. Finally, the vRNA can be detected as a foreign molecule by cytosolic sensors which trigger upon activation antiviral signaling pathways and the production of antiviral factors such as interferons and interferon-stimulated genes. However, to create an environment favorable to infection, flaviviruses have evolved mechanisms to dampen these antiviral processes, notably through the production of a specific vRNA degradation product termed subgenomic flavivirus RNA (sfRNA). In this review, we discuss the current understanding of the fates of flavivirus vRNA and how this is regulated at the molecular level to achieve an optimal replication within infected cells.
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Affiliation(s)
- Clément Mazeaud
- Institut National de la Recherche Scientifique, Centre INRS-Institut Armand-Frappier, Laval, QC, Canada
| | - Wesley Freppel
- Institut National de la Recherche Scientifique, Centre INRS-Institut Armand-Frappier, Laval, QC, Canada
| | - Laurent Chatel-Chaix
- Institut National de la Recherche Scientifique, Centre INRS-Institut Armand-Frappier, Laval, QC, Canada
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14
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Mazeaud C, Freppel W, Chatel-Chaix L. The Multiples Fates of the Flavivirus RNA Genome During Pathogenesis. Front Genet 2018; 9:595. [PMID: 30564270 PMCID: PMC6288177 DOI: 10.3389/fgene.2018.00595] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 11/15/2018] [Indexed: 12/11/2022] Open
Abstract
The Flavivirus genus comprises many viruses (including dengue, Zika, West Nile and yellow fever viruses) which constitute important public health concerns worldwide. For several of these pathogens, neither antivirals nor vaccines are currently available. In addition to this unmet medical need, flaviviruses are of particular interest since they constitute an excellent model for the study of spatiotemporal regulation of RNA metabolism. Indeed, with no DNA intermediate or nuclear step, the flaviviral life cycle entirely relies on the cytoplasmic fate of a single RNA species, namely the genomic viral RNA (vRNA) which contains all the genetic information necessary for optimal viral replication. From a single open reading frame, the vRNA encodes a polyprotein which is processed to generate the mature viral proteins. In addition to coding for the viral polyprotein, the vRNA serves as a template for RNA synthesis and is also selectively packaged into newly assembled viral particles. Notably, vRNA translation, replication and encapsidation must be tightly coordinated in time and space via a fine-tuned equilibrium as these processes cannot occur simultaneously and hence, are mutually exclusive. As such, these dynamic processes involve several vRNA secondary and tertiary structures as well as RNA modifications. Finally, the vRNA can be detected as a foreign molecule by cytosolic sensors which trigger upon activation antiviral signaling pathways and the production of antiviral factors such as interferons and interferon-stimulated genes. However, to create an environment favorable to infection, flaviviruses have evolved mechanisms to dampen these antiviral processes, notably through the production of a specific vRNA degradation product termed subgenomic flavivirus RNA (sfRNA). In this review, we discuss the current understanding of the fates of flavivirus vRNA and how this is regulated at the molecular level to achieve an optimal replication within infected cells.
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Affiliation(s)
- Clément Mazeaud
- Institut National de la Recherche Scientifique, Centre INRS-Institut Armand-Frappier, Laval, QC, Canada
| | - Wesley Freppel
- Institut National de la Recherche Scientifique, Centre INRS-Institut Armand-Frappier, Laval, QC, Canada
| | - Laurent Chatel-Chaix
- Institut National de la Recherche Scientifique, Centre INRS-Institut Armand-Frappier, Laval, QC, Canada
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15
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Slonchak A, Khromykh AA. Subgenomic flaviviral RNAs: What do we know after the first decade of research. Antiviral Res 2018; 159:13-25. [PMID: 30217649 DOI: 10.1016/j.antiviral.2018.09.006] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 09/10/2018] [Accepted: 09/10/2018] [Indexed: 12/13/2022]
Abstract
The common feature of flaviviral infection is the accumulation of abundant virus-derived noncoding RNA, named flaviviral subgenomic RNA (sfRNA) in infected cells. This RNA represents a product of incomplete degradation of viral genomic RNA by the cellular 5'-3' exoribonuclease XRN1 that stalls at the conserved highly structured elements in the 3' untranslated region (UTR). This mechanism of sfRNA generation was discovered a decade ago and since then sfRNA has been a focus of intense research. The ability of flaviviruses to produce sfRNA was shown to be evolutionary conserved in all members of Flavivirus genus. Mutations in the 3'UTR that affect production of sfRNAs and their interactions with host factors showed that sfRNAs are responsible for viral pathogenicity, host adaptation, and emergence of new pathogenic strains. RNA structural elements required for XRN1 stalling have been elucidated and the role of sfRNAs in inhibiting host antiviral responses in arthropod and vertebrate hosts has been demonstrated. Some molecular mechanisms determining these properties of sfRNA have been recently characterized, while other aspects of sfRNA functions remain an open avenue for future research. In this review we summarise the current state of knowledge on the mechanisms of generation and functional roles of sfRNAs in the life cycle of flaviviruses and highlight the gaps in our knowledge to be addressed in the future.
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Affiliation(s)
- Andrii Slonchak
- The Australian Infectious Disease Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD, 4072, Australia
| | - Alexander A Khromykh
- The Australian Infectious Disease Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD, 4072, Australia.
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16
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Mechanism and structural diversity of exoribonuclease-resistant RNA structures in flaviviral RNAs. Nat Commun 2018; 9:119. [PMID: 29317714 PMCID: PMC5760640 DOI: 10.1038/s41467-017-02604-y] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 12/12/2017] [Indexed: 01/21/2023] Open
Abstract
Flaviviruses such as Yellow fever, Dengue, West Nile, and Zika generate disease-linked viral noncoding RNAs called subgenomic flavivirus RNAs. Subgenomic flavivirus RNAs result when the 5'-3' progression of cellular exoribonuclease Xrn1 is blocked by RNA elements called Xrn1-resistant RNAs located within the viral genome's 3'-untranslated region that operate without protein co-factors. Here, we show that Xrn1-resistant RNAs can halt diverse exoribonucleases, revealing a mechanism in which they act as general mechanical blocks that 'brace' against an enzyme's surface, presenting an unfolding problem that confounds further enzyme progression. Further, we directly demonstrate that Xrn1-resistant RNAs exist in a diverse set of flaviviruses, including some specific to insects or with no known arthropod vector. These Xrn1-resistant RNAs comprise two secondary structural classes that mirror previously reported phylogenic analysis. Our discoveries have implications for the evolution of exoribonuclease resistance, the use of Xrn1-resistant RNAs in synthetic biology, and the development of new therapies.
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17
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Arbovirus Adaptation: Roles in Transmission and Emergence. CURRENT CLINICAL MICROBIOLOGY REPORTS 2017. [DOI: 10.1007/s40588-017-0068-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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18
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The 5' and 3' Untranslated Regions of the Flaviviral Genome. Viruses 2017; 9:v9060137. [PMID: 28587300 PMCID: PMC5490814 DOI: 10.3390/v9060137] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Revised: 05/16/2017] [Accepted: 05/29/2017] [Indexed: 01/30/2023] Open
Abstract
Flaviviruses are enveloped arthropod-borne viruses with a single-stranded, positive-sense RNA genome that can cause serious illness in humans and animals. The 11 kb 5′ capped RNA genome consists of a single open reading frame (ORF), and is flanked by 5′ and 3′ untranslated regions (UTR). The ORF is a polyprotein that is processed into three structural and seven non-structural proteins. The UTRs have been shown to be important for viral replication and immune modulation. Both of these regions consist of elements that are essential for genome cyclization, resulting in initiation of RNA synthesis. Genome mutation studies have been employed to investigate each component of the essential elements to show the necessity of each component and its role in viral RNA replication and growth. Furthermore, the highly structured 3′UTR is responsible for the generation of subgenomic flavivirus RNA (sfRNA) that helps the virus evade host immune response, thereby affecting viral pathogenesis. In addition, changes within the 3′UTR have been shown to affect transmissibility between vector and host, which can influence the development of vaccines.
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Fernández-Sanlés A, Ríos-Marco P, Romero-López C, Berzal-Herranz A. Functional Information Stored in the Conserved Structural RNA Domains of Flavivirus Genomes. Front Microbiol 2017; 8:546. [PMID: 28421048 PMCID: PMC5376627 DOI: 10.3389/fmicb.2017.00546] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 03/15/2017] [Indexed: 02/05/2023] Open
Abstract
The genus Flavivirus comprises a large number of small, positive-sense single-stranded, RNA viruses able to replicate in the cytoplasm of certain arthropod and/or vertebrate host cells. The genus, which has some 70 member species, includes a number of emerging and re-emerging pathogens responsible for outbreaks of human disease around the world, such as the West Nile, dengue, Zika, yellow fever, Japanese encephalitis, St. Louis encephalitis, and tick-borne encephalitis viruses. Like other RNA viruses, flaviviruses have a compact RNA genome that efficiently stores all the information required for the completion of the infectious cycle. The efficiency of this storage system is attributable to supracoding elements, i.e., discrete, structural units with essential functions. This information storage system overlaps and complements the protein coding sequence and is highly conserved across the genus. It therefore offers interesting potential targets for novel therapeutic strategies. This review summarizes our knowledge of the features of flavivirus genome functional RNA domains. It also provides a brief overview of the main achievements reported in the design of antiviral nucleic acid-based drugs targeting functional genomic RNA elements.
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Affiliation(s)
- Alba Fernández-Sanlés
- Department of Molecular Biology, Instituto de Parasitología y Biomedicina "López-Neyra," Consejo Superior de Investigaciones Científicas (IPBLN-CSIC)Granada, Spain
| | - Pablo Ríos-Marco
- Department of Molecular Biology, Instituto de Parasitología y Biomedicina "López-Neyra," Consejo Superior de Investigaciones Científicas (IPBLN-CSIC)Granada, Spain
| | - Cristina Romero-López
- Department of Molecular Biology, Instituto de Parasitología y Biomedicina "López-Neyra," Consejo Superior de Investigaciones Científicas (IPBLN-CSIC)Granada, Spain
| | - Alfredo Berzal-Herranz
- Department of Molecular Biology, Instituto de Parasitología y Biomedicina "López-Neyra," Consejo Superior de Investigaciones Científicas (IPBLN-CSIC)Granada, Spain
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20
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Filomatori CV, Carballeda JM, Villordo SM, Aguirre S, Pallarés HM, Maestre AM, Sánchez-Vargas I, Blair CD, Fabri C, Morales MA, Fernandez-Sesma A, Gamarnik AV. Dengue virus genomic variation associated with mosquito adaptation defines the pattern of viral non-coding RNAs and fitness in human cells. PLoS Pathog 2017; 13:e1006265. [PMID: 28264033 PMCID: PMC5354447 DOI: 10.1371/journal.ppat.1006265] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 03/16/2017] [Accepted: 02/28/2017] [Indexed: 12/23/2022] Open
Abstract
The Flavivirus genus includes a large number of medically relevant pathogens that cycle between humans and arthropods. This host alternation imposes a selective pressure on the viral population. Here, we found that dengue virus, the most important viral human pathogen transmitted by insects, evolved a mechanism to differentially regulate the production of viral non-coding RNAs in mosquitos and humans, with a significant impact on viral fitness in each host. Flavivirus infections accumulate non-coding RNAs derived from the viral 3’UTRs (known as sfRNAs), relevant in viral pathogenesis and immune evasion. We found that dengue virus host adaptation leads to the accumulation of different species of sfRNAs in vertebrate and invertebrate cells. This process does not depend on differences in the host machinery; but it was found to be dependent on the selection of specific mutations in the viral 3’UTR. Dissecting the viral population and studying phenotypes of cloned variants, the molecular determinants for the switch in the sfRNA pattern during host change were mapped to a single RNA structure. Point mutations selected in mosquito cells were sufficient to change the pattern of sfRNAs, induce higher type I interferon responses and reduce viral fitness in human cells, explaining the rapid clearance of certain viral variants after host change. In addition, using epidemic and pre-epidemic Zika viruses, similar patterns of sfRNAs were observed in mosquito and human infected cells, but they were different from those observed during dengue virus infections, indicating that distinct selective pressures act on the 3’UTR of these closely related viruses. In summary, we present a novel mechanism by which dengue virus evolved an RNA structure that is under strong selective pressure in the two hosts, as regulator of non-coding RNA accumulation and viral fitness. This work provides new ideas about the impact of host adaptation on the variability and evolution of flavivirus 3’UTRs with possible implications in virulence and viral transmission. Flaviviruses constitute the most important and diverse group of arthropod-transmitted viruses, including relevant human pathogens such as dengue, Zika, yellow fever, and West Nile viruses. The natural alternation of these viruses between vertebrate and invertebrate hosts imposes a selective pressure on the viral population, with potential epidemiological implications. However, the selective forces and mechanisms that act on the viral RNA during host adaptation are largely unknown. Using dengue virus, we found that viral replication in mosquito or human cells leads to the accumulation of different patterns of viral non-coding RNAs that differently regulate viral fitness in each host. Carrying out this process requires changes of the structure of the viral 3’UTR that is under strong selective pressure in the two hosts. Our findings provide the first link between flavivirus host adaptation, fitness, and the production of viral non-coding RNAs, and support a model in which opposite selective pressures in the two hosts drive flavivirus 3’UTR evolution.
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Affiliation(s)
- Claudia V. Filomatori
- Fundación Instituto Leloir-CONICET, Avenida Patricias Argentinas 435, Buenos Aires, Argentina
| | - Juan M. Carballeda
- Fundación Instituto Leloir-CONICET, Avenida Patricias Argentinas 435, Buenos Aires, Argentina
| | - Sergio M. Villordo
- Fundación Instituto Leloir-CONICET, Avenida Patricias Argentinas 435, Buenos Aires, Argentina
| | - Sebastian Aguirre
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Horacio M. Pallarés
- Fundación Instituto Leloir-CONICET, Avenida Patricias Argentinas 435, Buenos Aires, Argentina
| | - Ana M. Maestre
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Irma Sánchez-Vargas
- Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, USA
| | - Carol D. Blair
- Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, USA
| | - Cintia Fabri
- Departamento Investigación, Instituto Nacional de Enfermedades Virales Humanas "Dr. Julio I. Maiztegui", ANLIS, Pergamino, Argentina
| | - Maria A. Morales
- Departamento Investigación, Instituto Nacional de Enfermedades Virales Humanas "Dr. Julio I. Maiztegui", ANLIS, Pergamino, Argentina
| | - Ana Fernandez-Sesma
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Andrea V. Gamarnik
- Fundación Instituto Leloir-CONICET, Avenida Patricias Argentinas 435, Buenos Aires, Argentina
- * E-mail:
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21
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Sharma N, Singh SK. Implications of non-coding RNAs in viral infections. Rev Med Virol 2016; 26:356-68. [PMID: 27401792 DOI: 10.1002/rmv.1893] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 05/30/2016] [Accepted: 05/31/2016] [Indexed: 02/06/2023]
Abstract
The advances in RNA sequencing have unveiled various non-coding RNAs (ncRNAs), which modulate the gene expression. ncRNAs do not get translated into proteins. These include transfer RNAs, ribosomal RNAs, microRNA (miRNA), short interfering RNA, long non-coding RNA, piwi-interacting RNA and small nuclear RNA. ncRNAs regulate gene expression at various levels and control cellular machinery. miRNAs have been reported in plants, animals, several invertebrates and viruses. The miRNAs regulate the gene expression post-transcriptionally. Viral infection strongly influences the abundance and the distribution of miRNAs and other ncRNAs within the host cells. Viruses may encode their own miRNA, which help in the viral life cycle and other aspects of pathogenesis. Viruses are known to successfully modulate the expression pattern of ncRNAs. The ncRNA-based strategies adopted by viruses for their survival present a complex picture of host-virus interactions. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Nikhil Sharma
- Laboratory of Neurovirology and Inflammation Biology, CSIR-Centre for Cellular and Molecular Biology (CCMB), Hyderabad, India
| | - Sunit K Singh
- Laboratory of Human Molecular Virology and Immunology, Molecular Biology Unit, Faculty of Medicine, Institute of Medical Sciences (IMS), Banaras Hindu University (BHU), Varanasi, India.
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22
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Bavia L, Mosimann ALP, Aoki MN, Duarte Dos Santos CN. A glance at subgenomic flavivirus RNAs and microRNAs in flavivirus infections. Virol J 2016; 13:84. [PMID: 27233361 PMCID: PMC4884392 DOI: 10.1186/s12985-016-0541-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 05/17/2016] [Indexed: 11/10/2022] Open
Abstract
The family Flaviviridae comprises a wide variety of viruses that are distributed worldwide, some of which are associated with high rates of morbidity and mortality. There are neither vaccines nor antivirals for most flavivirus infections, reinforcing the importance of research on different aspects of the viral life cycle. During infection, cytoplasmic accumulation of RNA fragments mainly originating from the 3' UTRs, which have been designated subgenomic flavivirus RNAs (sfRNAs), has been detected. It has been shown that eukaryotic exoribonucleases are involved in viral sfRNA production. Additionally, viral and human small RNAs (sRNAs) have also been found in flavivirus-infected cells, especially microRNAs (miRNAs). miRNAs were first described in eukaryotic cells and in a mature and functional state present as single-stranded 18-24 nt RNA fragments. Their main function is the repression of translation through base pairing with cellular mRNAs, besides other functions, such as mRNA degradation. Canonical miRNA biogenesis involves Drosha and Dicer, however miRNA can also be generated by alternative pathways. In the case of flaviviruses, alternative pathways have been suggested. Both sfRNAs and miRNAs are involved in viral infection and host cell response modulation, representing interesting targets of antiviral strategies. In this review, we focus on the generation and function of viral sfRNAs, sRNAs and miRNAs in West Nile, dengue, Japanese encephalitis, Murray Valley encephalitis and yellow fever infections, as well as their roles in viral replication, translation and cell immune response evasion. We also give an overview regarding other flaviviruses and the generation of cellular miRNAs during infection.
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Affiliation(s)
- Lorena Bavia
- Laboratório de Virologia Molecular, Instituto Carlos Chagas (ICC/FIOCRUZ-PR), Rua Prof. Algacyr Munhoz Mader 3775, CIC, CEP: 81350-010, Curitiba, Paraná, Brazil
| | - Ana Luiza Pamplona Mosimann
- Laboratório de Virologia Molecular, Instituto Carlos Chagas (ICC/FIOCRUZ-PR), Rua Prof. Algacyr Munhoz Mader 3775, CIC, CEP: 81350-010, Curitiba, Paraná, Brazil
| | - Mateus Nóbrega Aoki
- Laboratório de Virologia Molecular, Instituto Carlos Chagas (ICC/FIOCRUZ-PR), Rua Prof. Algacyr Munhoz Mader 3775, CIC, CEP: 81350-010, Curitiba, Paraná, Brazil
| | - Claudia Nunes Duarte Dos Santos
- Laboratório de Virologia Molecular, Instituto Carlos Chagas (ICC/FIOCRUZ-PR), Rua Prof. Algacyr Munhoz Mader 3775, CIC, CEP: 81350-010, Curitiba, Paraná, Brazil.
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23
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Miller WA, Shen R, Staplin W, Kanodia P. Noncoding RNAs of Plant Viruses and Viroids: Sponges of Host Translation and RNA Interference Machinery. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2016; 29:156-64. [PMID: 26900786 PMCID: PMC5410770 DOI: 10.1094/mpmi-10-15-0226-fi] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Noncoding sequences in plant viral genomes are well-known to control viral replication and gene expression in cis. However, plant viral and viroid noncoding (nc)RNA sequences can also regulate gene expression acting in trans, often acting like 'sponges' that bind and sequester host cellular machinery to favor viral infection. Noncoding sequences of small subgenomic (sg)RNAs of Barley yellow dwarf virus (BYDV) and Red clover necrotic mosaic virus (RCNMV) contain a cap-independent translation element that binds translation initiation factor eIF4G. We provide new evidence that a sgRNA of BYDV can globally attenuate host translation, probably by sponging eIF4G. Subgenomic ncRNA of RCNMV is generated via 5' to 3' degradation by a host exonuclease. The similar noncoding subgenomic flavivirus (sf)RNA, inhibits the innate immune response, enhancing viral pathogenesis. Cauliflower mosaic virus transcribes massive amounts of a 600-nt ncRNA, which is processed into small RNAs that overwhelm the host's RNA interference (RNAi) system. Viroids use the host RNAi machinery to generate viroid-derived ncRNAs that inhibit expression of host defense genes by mimicking a microRNA. More examples of plant viral and viroid ncRNAs are likely to be discovered, revealing fascinating new weaponry in the host-virus arms race.
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Affiliation(s)
- W. Allen Miller
- Interdepartmental Genetics & Genomics Program, Iowa State University, Ames, IA 50011 USA
- Corresponding author:
| | - Ruizhong Shen
- Interdepartmental Genetics & Genomics Program, Iowa State University, Ames, IA 50011 USA
| | | | - Pulkit Kanodia
- Interdepartmental Genetics & Genomics Program, Iowa State University, Ames, IA 50011 USA
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24
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RNA Structure Duplications and Flavivirus Host Adaptation. Trends Microbiol 2016; 24:270-283. [PMID: 26850219 DOI: 10.1016/j.tim.2016.01.002] [Citation(s) in RCA: 121] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Revised: 01/04/2016] [Accepted: 01/08/2016] [Indexed: 01/11/2023]
Abstract
Flaviviruses include a highly diverse group of arboviruses with a global distribution and a high human disease burden. Most flaviviruses cycle between insects and vertebrate hosts; thus, they are obligated to use different cellular machinery for their replication and mount different mechanisms to evade specific antiviral responses. In addition to coding for viral proteins, the viral genome contains signals in RNA structures that govern the amplification of viral components and participate in triggering or evading antiviral responses. In this review, we focused on new information about host-specific functions of RNA structures present in the 3' untranslated region (3' UTR) of flavivirus genomes. Models and conservation patterns of RNA elements of distinct flavivirus ecological groups are revised. An intriguing feature of the 3' UTR of insect-borne flavivirus genomes is the conservation of complex RNA structure duplications. Here, we discuss new hypotheses of how these RNA elements specialize for replication in vertebrate and invertebrate hosts, and present new ideas associating the significance of RNA structure duplication, small subgenomic flavivirus RNA formation, and host adaptation.
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25
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Long noncoding RNAs: a potent source of regulation in immunity and disease. Immunol Cell Biol 2016; 93:277-83. [PMID: 25776990 DOI: 10.1038/icb.2015.2] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 12/06/2014] [Indexed: 12/14/2022]
Abstract
The discovery of functional long noncoding RNAs (lncRNAs) coupled with the ever-increasing accessibility of genomic and transcriptomic technology has led to an explosion of functional and mechanistic investigation and discovery into what was once dismissed as junk DNA. Over the past decade, a significant number of lncRNAs have been found to be involved in a diverse array of processes: from epigenetic modulation, both repressive and activating; to protein scaffolding; to miRNA sequestration; to competitive inhibition; and more. The broad character of these mechanisms means that lncRNAs have the potential for regulation across all biological processes-not least of which are immunity and disease. A number of lncRNAs operating within these two contexts have already been identified and characterized, but untold more remain yet to be discovered. This review aims to provide an overview of the current state of research on lncRNAs involved in immune modulation and disease, with an emphasis on their mechanism and discovery.
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Valadkhan S, Gunawardane LS. lncRNA-mediated regulation of the interferon response. Virus Res 2015; 212:127-36. [PMID: 26474526 PMCID: PMC4744491 DOI: 10.1016/j.virusres.2015.09.023] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 09/24/2015] [Accepted: 09/29/2015] [Indexed: 12/18/2022]
Abstract
A large number of lncRNAs are differentially expressed in response to IFN stimulation. Two IFN-induced lncRNAs act as negative regulators of the IFN response. Another IFN-induced lncRNA positively regulates the expression of its neighboring gene, BST2/Tetherin. Several virally-encoded lncRNAs increase viral pathogenicity by suppressing the IFN response.
The interferon (IFN) response is a critical arm of the innate immune response and a major host defense mechanism against viral infections. Following microbial encounter, a series of signaling events lead to transcriptional activation of the IFN genes, which in turn leads to significant changes in the cellular transcriptome by altering the expression of hundreds of target genes. Emerging evidence suggests that long non-coding RNAs (lncRNAs) constitute a major subgroup of the IFN target genes, and further, that the IFN response is subject to regulation by a large number of host- and pathogen-derived lncRNAs. While the vast majority of lncRNAs with potential roles in the IFN response remain unstudied, analysis of a very small subset provides a glimpse of the regulatory impact of this class of RNAs on IFN response.
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Affiliation(s)
- Saba Valadkhan
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106 USA.
| | - Lalith S Gunawardane
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106 USA.
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Manokaran G, Finol E, Wang C, Gunaratne J, Bahl J, Ong EZ, Tan HC, Sessions OM, Ward AM, Gubler DJ, Harris E, Garcia-Blanco MA, Ooi EE. Dengue subgenomic RNA binds TRIM25 to inhibit interferon expression for epidemiological fitness. Science 2015; 350:217-21. [PMID: 26138103 PMCID: PMC4824004 DOI: 10.1126/science.aab3369] [Citation(s) in RCA: 282] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 06/22/2015] [Indexed: 11/02/2022]
Abstract
The global spread of dengue virus (DENV) infections has increased viral genetic diversity, some of which appears associated with greater epidemic potential. The mechanisms governing viral fitness in epidemiological settings, however, remain poorly defined. We identified a determinant of fitness in a foreign dominant (PR-2B) DENV serotype 2 (DENV-2) clade, which emerged during the 1994 epidemic in Puerto Rico and replaced an endemic (PR-1) DENV-2 clade. The PR-2B DENV-2 produced increased levels of subgenomic flavivirus RNA (sfRNA) relative to genomic RNA during replication. PR-2B sfRNA showed sequence-dependent binding to and prevention of tripartite motif 25 (TRIM25) deubiquitylation, which is critical for sustained and amplified retinoic acid-inducible gene 1 (RIG-I)-induced type I interferon expression. Our findings demonstrate a distinctive viral RNA-host protein interaction to evade the innate immune response for increased epidemiological fitness.
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Affiliation(s)
- Gayathri Manokaran
- Program in Emerging Infectious Diseases, Duke-National University of Singapore Graduate Medical School, Singapore. Defence Medical and Environmental Research Institute, DSO National Laboratories, Singapore. Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Esteban Finol
- Program in Emerging Infectious Diseases, Duke-National University of Singapore Graduate Medical School, Singapore. Yong Loo Lin School of Medicine, National University of Singapore, Singapore. Swiss Tropical and Public Health Institute, Universität Basel, Switzerland
| | - Chunling Wang
- Division of Infectious Diseases and Vaccinology, School of Public Health, University of California, Berkeley, CA, USA
| | - Jayantha Gunaratne
- Yong Loo Lin School of Medicine, National University of Singapore, Singapore. Institute of Molecular and Cell Biology, Singapore
| | - Justin Bahl
- Center for Infectious Diseases, The University of Texas School of Public Health, Houston, TX, USA
| | - Eugenia Z Ong
- Program in Emerging Infectious Diseases, Duke-National University of Singapore Graduate Medical School, Singapore
| | - Hwee Cheng Tan
- Program in Emerging Infectious Diseases, Duke-National University of Singapore Graduate Medical School, Singapore
| | - October M Sessions
- Program in Emerging Infectious Diseases, Duke-National University of Singapore Graduate Medical School, Singapore
| | - Alex M Ward
- Program in Emerging Infectious Diseases, Duke-National University of Singapore Graduate Medical School, Singapore
| | - Duane J Gubler
- Program in Emerging Infectious Diseases, Duke-National University of Singapore Graduate Medical School, Singapore
| | - Eva Harris
- Division of Infectious Diseases and Vaccinology, School of Public Health, University of California, Berkeley, CA, USA
| | - Mariano A Garcia-Blanco
- Program in Emerging Infectious Diseases, Duke-National University of Singapore Graduate Medical School, Singapore. Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, TX, USA. Department of Molecular Genetics and Microbiology and Center for RNA Biology, Duke University, Durham, NC, USA
| | - Eng Eong Ooi
- Program in Emerging Infectious Diseases, Duke-National University of Singapore Graduate Medical School, Singapore. Yong Loo Lin School of Medicine, National University of Singapore, Singapore. Saw Swee Hock School of Public Health, National University of Singapore, Singapore. Singapore-Massachusetts Institute of Technology Alliance in Research and Technology Infectious Disease Interdisciplinary Research Group, Singapore.
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Kieft JS, Rabe JL, Chapman EG. New hypotheses derived from the structure of a flaviviral Xrn1-resistant RNA: Conservation, folding, and host adaptation. RNA Biol 2015; 12:1169-77. [PMID: 26399159 PMCID: PMC4829329 DOI: 10.1080/15476286.2015.1094599] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Arthropod-borne flaviviruses (FVs) are a growing world-wide health threat whose incidence and range are increasing. The pathogenicity and cytopathicity of these single-stranded RNA viruses are influenced by viral subgenomic non-protein-coding RNAs (sfRNAs) that the viruses produce to high levels during infection. To generate sfRNAs the virus co-opts the action of the abundant cellular exonuclease Xrn1, which is part of the cell's normal RNA turnover machinery. This exploitation of the cellular machinery is enabled by discrete, highly structured, Xrn1-resistant RNA elements (xrRNAs) in the 3'UTR that interact with Xrn1 to halt processive 5' to 3' decay of the viral genomic RNA. We recently solved the crystal structure of a functional xrRNA, revealing a novel fold that provides a mechanistic model for Xrn1 resistance. Continued analysis and interpretation of the structure reveals that the tertiary contacts that knit the xrRNA fold together are shared by a wide variety of arthropod-borne FVs, conferring robust Xrn1 resistance in all tested. However, there is some variability in the structures that correlates with unexplained patterns in the viral 3' UTRs. Finally, examination of these structures and their behavior in the context of viral infection leads to a new hypothesis linking RNA tertiary structure, overall 3' UTR architecture, sfRNA production, and host adaptation.
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Affiliation(s)
- Jeffrey S Kieft
- a Department of Biochemistry and Molecular Genetics.,b Howard Hughes Medical Institute; University of Colorado Denver; School of Medicine ; Aurora , CO USA
| | - Jennifer L Rabe
- c Department of Pediatrics ; University of Colorado Denver; School of Medicine ; Aurora , CO USA
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Mlera L, Melik W, Bloom ME. The role of viral persistence in flavivirus biology. Pathog Dis 2014; 71:137-63. [PMID: 24737600 PMCID: PMC4154581 DOI: 10.1111/2049-632x.12178] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 04/08/2014] [Accepted: 04/09/2014] [Indexed: 12/30/2022] Open
Abstract
In nature, vector borne flaviviruses are persistently cycled between either the tick or mosquito vector and small mammals such as rodents, skunks, and swine. These viruses account for considerable human morbidity and mortality worldwide. Increasing and substantial evidence of viral persistence in humans, which includes the isolation of RNA by RT PCR and infectious virus by culture, continues to be reported. Viral persistence can also be established in vitro in various human, animal, arachnid, and insect cell lines in culture. Although some research has focused on the potential roles of defective virus particles, evasion of the immune response through the manipulation of autophagy and/or apoptosis, the precise mechanism of flavivirus persistence is still not well understood. We propose additional research for further understanding of how viral persistence is established in different systems. Avenues for additional studies include determining whether the multifunctional flavivirus protein NS5 has a role in viral persistence, the development of relevant animal models of viral persistence, and investigating the host responses that allow vector borne flavivirus replication without detrimental effects on infected cells. Such studies might shed more light on the viral–host relationships and could be used to unravel the mechanisms for establishment of persistence. Persistent infections by vector borne flaviviruses are an important, but inadequately studied topic.
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Affiliation(s)
- Luwanika Mlera
- Rocky Mountain Laboratories, Laboratory of Virology, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
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Chapman EG, Costantino DA, Rabe JL, Moon SL, Wilusz J, Nix JC, Kieft JS. The structural basis of pathogenic subgenomic flavivirus RNA (sfRNA) production. Science 2014; 344:307-10. [PMID: 24744377 PMCID: PMC4163914 DOI: 10.1126/science.1250897] [Citation(s) in RCA: 182] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Flaviviruses are emerging human pathogens and worldwide health threats. During infection, pathogenic subgenomic flaviviral RNAs (sfRNAs) are produced by resisting degradation by the 5'→3' host cell exonuclease Xrn1 through an unknown RNA structure-based mechanism. Here, we present the crystal structure of a complete Xrn1-resistant flaviviral RNA, which contains interwoven pseudoknots within a compact structure that depends on highly conserved nucleotides. The RNA's three-dimensional topology creates a ringlike conformation, with the 5' end of the resistant structure passing through the ring from one side of the fold to the other. Disruption of this structure prevents formation of sfRNA during flaviviral infection. Thus, sfRNA formation results from an RNA fold that interacts directly with Xrn1, presenting the enzyme with a structure that confounds its helicase activity.
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Affiliation(s)
- Erich G Chapman
- Department of Biochemistry and Molecular Genetics, School of Medicine, University of Colorado Denver, Aurora, CO 80045, USA
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Chapman EG, Moon SL, Wilusz J, Kieft JS. RNA structures that resist degradation by Xrn1 produce a pathogenic Dengue virus RNA. eLife 2014; 3:e01892. [PMID: 24692447 PMCID: PMC3968743 DOI: 10.7554/elife.01892] [Citation(s) in RCA: 142] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Dengue virus is a growing global health threat. Dengue and other flaviviruses commandeer the host cell’s RNA degradation machinery to generate the small flaviviral RNA (sfRNA), a noncoding RNA that induces cytopathicity and pathogenesis. Host cell exonuclease Xrn1 likely loads on the 5′ end of viral genomic RNA and degrades processively through ∼10 kB of RNA, halting near the 3′ end of the viral RNA. The surviving RNA is the sfRNA. We interrogated the architecture of the complete Dengue 2 sfRNA, identifying five independently-folded RNA structures, two of which quantitatively confer Xrn1 resistance. We developed an assay for real-time monitoring of Xrn1 resistance that we used with mutagenesis and RNA folding experiments to show that Xrn1-resistant RNAs adopt a specific fold organized around a three-way junction. Disrupting the junction’s fold eliminates the buildup of disease-related sfRNAs in human cells infected with a flavivirus, directly linking RNA structure to sfRNA production. DOI:http://dx.doi.org/10.7554/eLife.01892.001 More than 40% of people around the globe are at risk of being bitten by mosquitoes infected with the virus that causes Dengue fever. Every year, more than 100 million of these individuals are infected. Many develop severe headaches, pain, and fever, but some develop a life-threatening condition where tiny blood vessels in the body begin to leak. If not treated quickly, this more severe manifestation of the illness can lead to death. There are currently no specific therapies or vaccines against Dengue or many other closely related viruses such as West Nile and Japanese Encephalitis. These viruses use instructions encoded in a single strand of RNA to take over an infected cell and to reproduce. The viruses also exploit an enzyme that cells use to destroy RNA to instead produce short stretches of RNA called sfRNAs that, among other things, may help the virus to avoid the immune system of its host. Understanding exactly how Dengue and other viruses thwart this enzyme—which is called Xrn1—may help scientists develop treatments or vaccines for these diseases. Chapman et al. have now shown that Dengue virus RNA contains a number of RNA elements that prevent it being completely degraded by the Xrn1 enzyme. In particular, a junction formed by three RNA helixes is critical for stopping the enzyme in its tracks, leaving the disease-associated sfRNA behind. A single mutation in the Dengue RNA disrupts the structure of the three-helix junction and allows the enzyme to completely destroy the RNA. A similar mutation was also made in the West Nile virus RNA and when human cells were infected with the mutated West Nile virus, the short sfRNAs were not produced. Treatments or vaccines targeting this structure may therefore help reduce illness associated with Dengue and related viruses. DOI:http://dx.doi.org/10.7554/eLife.01892.002
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Affiliation(s)
- Erich G Chapman
- Department of Biochemistry and Molecular Genetics, Howard Hughes Medical Institute, University of Colorado Denver School of Medicine, Aurora, United States
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Roby JA, Pijlman GP, Wilusz J, Khromykh AA. Noncoding subgenomic flavivirus RNA: multiple functions in West Nile virus pathogenesis and modulation of host responses. Viruses 2014; 6:404-27. [PMID: 24473339 PMCID: PMC3939463 DOI: 10.3390/v6020404] [Citation(s) in RCA: 116] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Revised: 01/13/2014] [Accepted: 01/15/2014] [Indexed: 12/11/2022] Open
Abstract
Flaviviruses are a large group of positive strand RNA viruses transmitted by arthropods that include many human pathogens such as West Nile virus (WNV), Japanese encephalitis virus (JEV), yellow fever virus, dengue virus, and tick-borne encephalitis virus. All members in this genus tested so far are shown to produce a unique subgenomic flavivirus RNA (sfRNA) derived from the 3' untranslated region (UTR). sfRNA is a product of incomplete degradation of genomic RNA by the cell 5'–3' exoribonuclease XRN1 which stalls at highly ordered secondary RNA structures at the beginning of the 3'UTR. Generation of sfRNA results in inhibition of XRN1 activity leading to an increase in stability of many cellular mRNAs. Mutant WNV deficient in sfRNA generation was highly attenuated displaying a marked decrease in cytopathicity in cells and pathogenicity in mice. sfRNA has also been shown to inhibit the antiviral activity of IFN-α/β by yet unknown mechanism and of the RNAi pathway by likely serving as a decoy substrate for Dicer. Thus, sfRNA is involved in modulating multiple cellular pathways to facilitate viral pathogenicity; however the overlying mechanism linking all these multiple functions of sfRNA remains to be elucidated.
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Affiliation(s)
- Justin A Roby
- Australian Infectious Disease Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Brisbane 4072, Australia.
| | - Gorben P Pijlman
- Laboratory of Virology, Wageningen University, Wageningen, 6708NW, The Netherlands.
| | - Jeffrey Wilusz
- Department of Microbiology, Immunology & Pathology, Colorado State University Fort Collins, CO 80523, USA;.
| | - Alexander A Khromykh
- Australian Infectious Disease Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Brisbane 4072, Australia.
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33
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Bhattacharyya S, Sen U, Vrati S. Regulated IRE1-dependent decay pathway is activated during Japanese encephalitis virus-induced unfolded protein response and benefits viral replication. J Gen Virol 2013; 95:71-79. [PMID: 24114795 DOI: 10.1099/vir.0.057265-0] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Japanese encephalitis virus (JEV) infection-induced encephalitis causes extensive death or long-term neurological damage, especially among children, in south and south-east Asia. Infection of mammalian cells has shown induction of an unfolded protein response (UPR), presumably leading to programmed cell death or apoptosis of the host cells. UPR, a cellular response to accumulation of unfolded or misfolded proteins in the endoplasmic reticulum (ER) lumen, is initiated by three ER-lumen-resident sensors (PERK, IRE1 and ATF6), and involves transcriptional and translational regulation of the expression of several genes. The sensor IRE1 possesses an intrinsic RNase activity, activated through homo-dimerization and autophosphorylation during UPR. Activated IRE1 performs cytoplasmic cleavage of Xbp1u transcripts, thus facilitating synthesis of XBP1S transcription factor, in addition to cleavage of a cohort of cellular transcripts, the later initiating the regulated IRE1-dependent decay (RIDD) pathway. In this study, we report the initiation of the RIDD pathway in JEV-infected mouse neuroblastoma cells (Neuro2a) and its effect on viral infection. Activation of the RIDD pathway led to degradation of known mouse cell target transcripts without showing any effect on JEV RNA despite the fact that both when biochemically purified showed significant enrichment in ER membrane-enriched fractions. Additionally, inhibition of the IRE1 RNase activity by STF083010, a specific drug, diminished viral protein levels and reduced the titre of the virus produced from infected Neuro2a cells. The results present evidence for the first report of a beneficial effect of RIDD activation on the viral life cycle.
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Affiliation(s)
- Sankar Bhattacharyya
- Vaccine and Infectious Disease Research Centre, Translational Health Science and Technology Institute, 496, Udyog Vihar Phase III, Gurgaon 122016, India
| | - Utsav Sen
- Vaccine and Infectious Disease Research Centre, Translational Health Science and Technology Institute, 496, Udyog Vihar Phase III, Gurgaon 122016, India
| | - Sudhanshu Vrati
- Vaccine and Infectious Disease Research Centre, Translational Health Science and Technology Institute, 496, Udyog Vihar Phase III, Gurgaon 122016, India
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Japanese encephalitis virus non-coding RNA inhibits activation of interferon by blocking nuclear translocation of interferon regulatory factor 3. Vet Microbiol 2013; 166:11-21. [PMID: 23755934 DOI: 10.1016/j.vetmic.2013.04.026] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Revised: 04/26/2013] [Accepted: 04/30/2013] [Indexed: 12/24/2022]
Abstract
Noncoding RNA (ncRNA) plays a critical role in modulating a broad range of diseases. All arthropod-borne flaviviruses produce short fragment ncRNA (sfRNA) collinear with highly conserved regions of the 3'-untranslated region (UTR) in the viral genome. We show that the molar ratio of sfRNA to genomic RNA in Japanese encephalitis virus (JEV) persistently infected cells is greater than that in acutely infected cells, indicating an sfRNA role in establishing persistent infection. Transfecting excess quantities of sfRNA into JEV-infected cells reduced interferon-β (IFN-β) promoter activity by 57% and IFN-β mRNA levels by 52%, compared to mock-transfected cells. Transfection of sfRNA into JEV-infected cells also reduced phosphorylation of interferon regulatory factor-3 (IRF-3), the IFN-β upstream regulator, and blocked roughly 30% of IRF-3 nuclear localization. Furthermore, JEV-infected sfRNA transfected cells produced 23% less IFN-β-stimulated apoptosis than mock-transfected groups did. Taken together, these results suggest that sfRNA plays a role against host-cell antiviral responses, prevents cells from undergoing apoptosis, and thus contributes to viral persistence.
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Abstract
In this review, we focus on the roles of long noncoding RNAs (lncRNAs), including cellular and viral lncRNAs, in virus replication in infected cells. We survey the interactions and functions of several cellular lncRNAs such as XIST, HOTAIR, NEAT1, BIC, and several virus-encoded lncRNAs.
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Affiliation(s)
- Quan Zhang
- Molecular Virology Section, Laboratory of Molecular Microbiology, National Institutes of Allergy and Infectious Diseases, the National Institutes of Health, Bethesda, Maryland 20892-0460, USA
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Ivanyi-Nagy R, Darlix JL. Reprint of: Core protein-mediated 5'-3' annealing of the West Nile virus genomic RNA in vitro. Virus Res 2012; 169:448-57. [PMID: 23022255 PMCID: PMC7172194 DOI: 10.1016/j.virusres.2012.09.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Revised: 05/08/2012] [Accepted: 05/08/2012] [Indexed: 12/21/2022]
Abstract
Genome cyclization through conserved RNA sequences located in the 5' and 3' terminal regions of flavivirus genomic RNA is essential for virus replication. Although the role of various cis-acting RNA elements in panhandle formation is well characterized, almost nothing is known about the potential contribution of protein cofactors to viral RNA cyclization. Proteins with nucleic acid chaperone activities are encoded by many viruses (e.g., retroviruses, coronaviruses) to facilitate RNA structural rearrangements and RNA-RNA interactions during the viral replicative cycle. Since the core protein of flaviviruses is also endowed with potent RNA chaperone activities, we decided to examine the effect of West Nile virus (WNV) core on 5'-3' genomic RNA annealing in vitro. Core protein binding resulted in a dramatic, dose-dependent increase in 5'-3' complex formation. Mutations introduced in either the UAR (upstream AUG region) or CS (conserved sequence) elements of the viral RNA diminished core protein-dependent annealing, while compensatory mutations restored the 5'-3' RNA interaction. The activity responsible for stimulating RNA annealing was mapped to the C-terminal RNA-binding region of WNV core protein. These results indicate that core protein - besides its function in viral particle formation - might be involved in the regulation of flavivirus genomic RNA cyclization, and thus virus replication.
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Affiliation(s)
- Roland Ivanyi-Nagy
- LaboRetro, INSERM U758, Ecole Normale Supérieure de Lyon, IFR128 Biosciences Lyon-Gerland, 46 allée d'Italie, 69364 Lyon, France
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Ivanyi-Nagy R, Darlix JL. Core protein-mediated 5'-3' annealing of the West Nile virus genomic RNA in vitro. Virus Res 2012; 167:226-35. [PMID: 22652509 PMCID: PMC7172325 DOI: 10.1016/j.virusres.2012.05.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Revised: 05/08/2012] [Accepted: 05/08/2012] [Indexed: 01/17/2023]
Abstract
Genome cyclization through conserved RNA sequences located in the 5' and 3' terminal regions of flavivirus genomic RNA is essential for virus replication. Although the role of various cis-acting RNA elements in panhandle formation is well characterized, almost nothing is known about the potential contribution of protein cofactors to viral RNA cyclization. Proteins with nucleic acid chaperone activities are encoded by many viruses (e.g., retroviruses, coronaviruses) to facilitate RNA structural rearrangements and RNA-RNA interactions during the viral replicative cycle. Since the core protein of flaviviruses is also endowed with potent RNA chaperone activities, we decided to examine the effect of West Nile virus (WNV) core on 5'-3' genomic RNA annealing in vitro. Core protein binding resulted in a dramatic, dose-dependent increase in 5'-3' complex formation. Mutations introduced in either the UAR (upstream AUG region) or CS (conserved sequence) elements of the viral RNA diminished core protein-dependent annealing, while compensatory mutations restored the 5'-3' RNA interaction. The activity responsible for stimulating RNA annealing was mapped to the C-terminal RNA-binding region of WNV core protein. These results indicate that core protein - besides its function in viral particle formation - might be involved in the regulation of flavivirus genomic RNA cyclization, and thus virus replication.
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Key Words
- cs, conserved sequence
- dar, downstream aug region
- db, dumbbell-like structure
- denv, dengue virus
- jev, japanese encephalitis virus
- orf, open reading frame
- rdrp, rna-dependent rna polymerase
- sfrna, subgenomic flavivirus rna
- tbev, tick-borne encephalitis virus
- uar, upstream aug region
- utr, untranslated region
- wnv, west nile virus
- yfv, yellow fever virus
- west nile virus
- core protein
- flaviviruses
- viral replication
- genome cyclization
- rna chaperoning
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Affiliation(s)
| | - Jean-Luc Darlix
- LaboRetro, INSERM U758, Ecole Normale Supérieure de Lyon, IFR128 Biosciences Lyon-Gerland, 46 allée d’Italie, 69364 Lyon, France
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Comparative evaluation of permissiveness to dengue virus serotype 2 infection in primary rodent macrophages. J Trop Med 2012; 2012:950303. [PMID: 22529871 PMCID: PMC3317054 DOI: 10.1155/2012/950303] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Accepted: 12/19/2011] [Indexed: 11/18/2022] Open
Abstract
Infection with dengue virus presents a broad clinical spectrum, which can range from asymptomatic cases to severe cases that are characterised by haemorrhagic syndrome and/or shock. The reason for such variability remains unknown. This work evaluated the in vitro permissiveness of mouse, rat, hamster and guinea pig macrophages to infection by dengue virus 2 (DENV2). The results established that macrophages derived from the BALB/c mouse strain showed higher permissiveness to DENV2 infection than macrophages from other rodent species, although all rodent species studied had the C820T mutation in the oligoadenylate synthetase 1b gene, indicating no relationship to the different in vitro susceptibilities of mouse cells at this locus. Other molecular mechanisms related to flavivirus susceptibility remain to be explored.
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West Nile virus noncoding subgenomic RNA contributes to viral evasion of the type I interferon-mediated antiviral response. J Virol 2012; 86:5708-18. [PMID: 22379089 DOI: 10.1128/jvi.00207-12] [Citation(s) in RCA: 144] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We previously showed that a noncoding subgenomic flavivirus RNA (sfRNA) is required for viral pathogenicity, as a mutant West Nile virus (WNV) deficient in sfRNA production replicated poorly in wild-type mice. To investigate the possible immunomodulatory or immune evasive functions of sfRNA, we utilized mice and cells deficient in elements of the type I interferon (IFN) response. Replication of the sfRNA mutant WNV was rescued in mice and cells lacking interferon regulatory factor 3 (IRF-3) and IRF-7 and in mice lacking the type I alpha/beta interferon receptor (IFNAR), suggesting a contribution for sfRNA in overcoming the antiviral response mediated by type I IFN. This was confirmed by demonstrating rescue of mutant virus replication in the presence of IFNAR neutralizing antibodies, greater sensitivity of mutant virus replication to IFN-α pretreatment, partial rescue of its infectivity in cells deficient in RNase L, and direct effects of transfected sfRNA on rescuing replication of unrelated Semliki Forest virus in cells pretreated with IFN-α. The results define a novel function of sfRNA in flavivirus pathogenesis via its contribution to viral evasion of the type I interferon response.
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Elbahesh H, Scherbik SV, Brinton MA. West Nile virus infection does not induce PKR activation in rodent cells. Virology 2011; 421:51-60. [PMID: 21982595 DOI: 10.1016/j.virol.2011.08.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Revised: 05/21/2011] [Accepted: 08/14/2011] [Indexed: 11/16/2022]
Abstract
dsRNA-activated protein kinase (PKR) is activated by viral dsRNAs and phosphorylates eIF2a reducing translation of host and viral mRNA. Although infection with a chimeric West Nile virus (WNV) efficiently induced PKR and eIF2a phosphorylation, infections with natural lineage 1 or 2 strains did not. Investigation of the mechanism of suppression showed that among the cellular PKR inhibitor proteins tested, only Nck, known to interact with inactive PKR, colocalized and co-immunoprecipitated with PKR in WNV-infected cells and PKR phosphorylation did not increase in infected Nck1,2-/- cells. Several WNV stem-loop RNAs efficiently activated PKR in vitro but not in infected cells. WNV infection did not interfere with intracellular PKR activation by poly(I:C) and similar virus yields were produced by control and PKR-/- cells. The results indicate that PKR phosphorylation is not actively suppressed in WNV-infected cells but that PKR is not activated by the viral dsRNA in infected cells.
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Affiliation(s)
- H Elbahesh
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA
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41
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Shueb RH, Papadimitriou J, Urosevic N. Fatal persistence of West Nile virus subtype Kunjin in the brains of flavivirus resistant mice. Virus Res 2010; 155:455-61. [PMID: 21167228 DOI: 10.1016/j.virusres.2010.12.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2010] [Revised: 12/02/2010] [Accepted: 12/07/2010] [Indexed: 11/26/2022]
Abstract
Flaviviruses cause febrile illnesses in humans that may progress to encephalitis and death. Both viral and host factors determine the level of virus replication and outcome of infection. In mice, genetically determined resistance conferred by the flavivirus resistance locus (Flv) is responsible for the restricted flavivirus replication and prevention of disease development. Majority of flaviviruses express significant virulence, replicate to high titers and cause high mortality in susceptible mice, while congenic resistant mice endure the infection, show significantly reduced levels of virus replication and remain healthy. In contrast, infection with West Nile virus subtype Kunjin (KUNV) causes morbidity and fatal outcomes even in mice that are naturally resistant to flaviviruses. There are two possible mechanisms that could account for such an unforeseen virulence of KUNV in resistant mice: (a) an abrogation of Flv-controlled natural resistance leading to high virus replication, or (b) massive virus-induced immunopathology in the brain. To identify the cause(s) of fatality of KUNV infection, disease progression, virus replication and brain histopathology were studied in parallel in resistant and congenic susceptible mice. While KUNV replicated to high titers causing early fatalities in susceptible mice, it showed only reduced replication associated with the delayed morbidity in resistant mice indicating no abrogation of the Flv resistance. No evidence of excessive immune cell infiltration and tissue damage following KUNV infection were found. However, incomplete KUNV clearance not previously described was perceived as an important source of pathogenesis in resistant mice.
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Affiliation(s)
- Rafidah H Shueb
- Microbiology and Immunology, School of Biomedical, Biomolecular and Chemical Sciences, The University of Western Australia, Crawly, Western Australia, Australia
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42
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An RNA pseudoknot is required for production of yellow fever virus subgenomic RNA by the host nuclease XRN1. J Virol 2010; 84:11395-406. [PMID: 20739539 DOI: 10.1128/jvi.01047-10] [Citation(s) in RCA: 130] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cells and mice infected with arthropod-borne flaviviruses produce a small subgenomic RNA that is colinear with the distal part of the viral 3'-untranslated region (UTR). This small subgenomic flavivirus RNA (sfRNA) results from the incomplete degradation of the viral genome by the host 5'-3' exonuclease XRN1. Production of the sfRNA is important for the pathogenicity of the virus. This study not only presents a detailed description of the yellow fever virus (YFV) sfRNA but, more importantly, describes for the first time the molecular characteristics of the stalling site for XRN1 in the flavivirus genome. Similar to the case for West Nile virus, the YFV sfRNA was produced by XRN1. However, in contrast to the case for other arthropod-borne flaviviruses, not one but two sfRNAs were detected in YFV-infected mammalian cells. The smaller of these two sfRNAs was not observed in infected mosquito cells. The larger sfRNA could also be produced in vitro by incubation with purified XRN1. These two YFV sfRNAs formed a 5'-nested set. The 5' ends of the YFV sfRNAs were found to be just upstream of the previously predicted RNA pseudoknot PSK3. RNA structure probing and mutagenesis studies provided strong evidence that this pseudoknot structure was formed and served as the molecular signal to stall XRN1. The sequence involved in PSK3 formation was cloned into the Sinrep5 expression vector and shown to direct the production of an sfRNA-like RNA. These results underscore the importance of the RNA pseudoknot in stalling XRN1 and also demonstrate that it is the sole viral requirement for sfRNA production.
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43
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[Viral noncoding RNAs]. Uirusu 2010; 59:179-87. [PMID: 20218326 DOI: 10.2222/jsv.59.179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Many lines of recent evidence indicate that non-coding RNAs including micro RNAs (miRNAs) and small interfering RNAs (siRNAs) play an important role in the control of gene expression in diverse cellular processes and in defense responses against molecular parasites such as viruses and transposons. Viruses also use many different types of non-coding RNAs for regulating expression of their own genome or host genome temporally and spatially to ensure efficient virus proliferation and/or latency in the host cell. Here, we introduce the generation mechanisms and functions of novel non-coding RNAs generated from both animal and plant RNA viruses, after a brief review of non-coding RNAs of DNA viruses.
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44
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Pijlman GP, Funk A, Kondratieva N, Leung J, Torres S, van der Aa L, Liu WJ, Palmenberg AC, Shi PY, Hall RA, Khromykh AA. A highly structured, nuclease-resistant, noncoding RNA produced by flaviviruses is required for pathogenicity. Cell Host Microbe 2009; 4:579-91. [PMID: 19064258 DOI: 10.1016/j.chom.2008.10.007] [Citation(s) in RCA: 348] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2008] [Revised: 06/10/2008] [Accepted: 10/15/2008] [Indexed: 01/01/2023]
Abstract
Viral noncoding RNAs have been shown to play an important role in virus-host interplay to facilitate virus replication. We report that members of the genus Flavivirus, a large group of medically important encephalitic RNA viruses, produce a unique and highly structured noncoding RNA of 0.3-0.5 kb derived from the 3' untranslated region of the viral genome. Using West Nile virus as a model, we show that this subgenomic RNA is a product of incomplete degradation of viral genomic RNA by cellular ribonucleases. Highly conserved RNA structures located at the beginning of the 3' untranslated region render this RNA resistant to nucleases, and the resulting subgenomic RNA product is essential for virus-induced cytopathicity and pathogenicity. Thus, flaviviruses evolved a unique strategy to generate a noncoding RNA product that allows them to kill the host more efficiently.
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Affiliation(s)
- Gorben P Pijlman
- School of Molecular and Microbial Sciences, The University of Queensland, Brisbane, Queensland, Australia
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Maeda A, Maeda J, Takagi H, Kurane I. Detection of small RNAs containing the 5'- and the 3'-end sequences of viral genome during West Nile virus replication. Virology 2007; 371:130-8. [PMID: 17963811 DOI: 10.1016/j.virol.2007.09.018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2007] [Revised: 07/31/2007] [Accepted: 09/18/2007] [Indexed: 10/22/2022]
Abstract
In the first step of flavivirus replication, the 5'-end of viral genomic RNA is thought to interact with the 3'-end of the genomic RNA at the complimentary sequences (CSs) located at both ends of the genomic RNA. However, there is little evidence of direct interaction between the two ends of the viral genomic RNA in virus-replicating cells. Herein, we show that viral small negative-strand RNA species, composed of two ends corresponding to the upstream of the 5'-end CS and the downstream of the 3'-end CS of viral genomic RNA, were synthesized during viral replication. We hypothesized that the viral small negative-sense RNAs were synthesized during viral negative-sense RNA synthesis through the template-jumping of viral RNA-dependent RNA polymerase from the 3'-end to the 5'-end of viral genomic RNA used as a template. Our present results strongly indicate that the two ends of viral genomic RNA associate with each other during viral replication.
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Affiliation(s)
- Akihiko Maeda
- Department of Prion Diseases, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
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Yagi S, Mori K, Shiota K. Implications of the HCV subgenome discovery for viral pathogenesis, persistence and proliferation. Future Virol 2006. [DOI: 10.2217/17460794.1.4.425] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The hepatitis C virus (HCV) subgenome with an in-frame deletion for envelope proteins has been identified in active chronic hepatitis C patients. The revealed features of the HCV subgenome share structural and biological similarities with the defective interfering particles of the RNA viruses, thus suggesting that the HCV subgenome is probably an HCV-defective interfering genome. The HCV subgenome provides an insight into the life cycle of HCV, the mechanisms of RNA replication and virus packaging, and the etiology of the progressive worsening of HCV-induced liver disease.
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Affiliation(s)
- Shintaro Yagi
- Laboratory of Cellular Biochemistry, Department of Animal Resource Sciences, Graduate School of Agricultural & Life Sciences, The Universit of Tokyo 1–1-1 Yayoi, Bunkyo-ku, Tokyo, 113–8657, Japan
| | - Kenichi Mori
- Advanced Life Science Institute, Inc., 2–10–23 Maruyamadi, Wako, Saitama, 351–0112, Japan
| | - Kunio Shiota
- Laboratory of Cellular Biochemistry, Department of Animal Resource Sciences, Graduate School of Agricultural & Life Sciences, The Universit of Tokyo 1–1-1 Yayoi, Bunkyo-ku, Tokyo, 113–8657, Japan
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Scherbik SV, Paranjape JM, Stockman BM, Silverman RH, Brinton MA. RNase L plays a role in the antiviral response to West Nile virus. J Virol 2006; 80:2987-99. [PMID: 16501108 PMCID: PMC1395436 DOI: 10.1128/jvi.80.6.2987-2999.2006] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Alleles at the Flv locus determine disease outcome after a flavivirus infection in mice. Although comparable numbers of congenic resistant and susceptible mouse embryo fibroblasts (MEFs) are infected by the flavivirus West Nile virus (WNV), resistant MEFs produce approximately 100- to 150-fold lower titers than susceptible ones and flavivirus titers in the brains of resistant and susceptible animals can differ by >10,000-fold. The Flv locus was previously identified as the 2'-5' oligoadenylate synthetase 1b (Oas1b) gene. Oas gene expression is up-regulated by interferon (IFN), and after activation by double-stranded RNA, some mouse synthetases produce 2-5A, which activates latent RNase L to degrade viral and cellular RNAs. To determine whether the lower levels of intracellular flavivirus genomic RNA from resistant mice detected in cells at all times after infection were mediated by RNase L, RNase L activity levels in congenic resistant and susceptible cells were compared. Similar moderate levels of RNase L activation by transfected 2-5A were observed in both types of uninfected cells. After WNV infection, the mRNAs of IFN-beta and three Oas genes were up-regulated to similar levels in both types of cells. However, significant levels of RNase L activity were not detected until 72 h after WNV infection and the patterns of viral RNA cleavage products generated were similar in both types of cells. When RNase L activity was down-regulated in resistant cells via stable expression of a dominant negative RNase L mutant, approximately 5- to 10-times-higher yields of WNV were produced. Similarly, about approximately 5- to 10-times-higher virus yields were produced by susceptible C57BL/6 RNase L-/- cells compared to RNase L+/+ cells that were either left untreated or pretreated with IFN and/or poly(I) . poly(C). The data indicate that WNV genomic RNA is susceptible to RNase L cleavage and that RNase L plays a role in the cellular antiviral response to flaviviruses. The results suggest that RNase L activation is not a major component of the Oas1b-mediated flavivirus resistance phenotype.
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Affiliation(s)
- Svetlana V Scherbik
- Department of Biology, Georgia State University, P.O. Box 4010, Atlanta, Georgia 30302-4010, USA
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Pantelic L, Sivakumaran H, Urosevic N. Differential induction of antiviral effects against West Nile virus in primary mouse macrophages derived from flavivirus-susceptible and congenic resistant mice by alpha/beta interferon and poly(I-C). J Virol 2005; 79:1753-64. [PMID: 15650200 PMCID: PMC544086 DOI: 10.1128/jvi.79.3.1753-1764.2005] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
A cell model of primary macrophages isolated from the peritoneal cavity of flavivirus-susceptible and congenic resistant mice has been used to study the extent and kinetics of antiviral effects against West Nile virus upon priming with alpha/beta interferon (IFN-alpha/beta) or poly(I-C) (pIC). The pattern of flavivirus resistance expressed after priming of cells in this model was in good agreement with the pattern of flavivirus resistance described in the brains of the corresponding mouse strains. While priming with either IFN-alpha/beta or pIC completely blocked flavivirus replication in macrophages from resistant mice, it only transiently reduced flavivirus replication in macrophages from susceptible mice. It was only the combined pretreatment with IFN-alpha/beta and pIC that elicited strong antiviral responses that completely prevented flavivirus replication in macrophages from susceptible mice. Primary macrophages isolated from the blood of healthy human donors expressed a similar need for double-stranded RNA (dsRNA) cofactor in developing efficient antiviral responses against West Nile virus. These findings reveal that the inefficient IFN-alpha/beta-induced antiviral effects against flaviviruses in cells from susceptible hosts could be successfully complemented by an external dsRNA factor leading to the complete eradication of the virus. This treatment appears to compensate for the lack of an inborn resistance mechanism in cells from the susceptible host. Furthermore, it may also provide useful clues for the prevention and treatment of flavivirus infections.
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Affiliation(s)
- Ljiljana Pantelic
- Microbiology, School of Biomedical and Chemical Sciences, University of Western Australia, 35 Stirling Hwy., Crawley, Western Australia 6009
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Lin KC, Chang HL, Chang RY. Accumulation of a 3'-terminal genome fragment in Japanese encephalitis virus-infected mammalian and mosquito cells. J Virol 2004; 78:5133-8. [PMID: 15113895 PMCID: PMC400339 DOI: 10.1128/jvi.78.10.5133-5138.2004] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Japanese encephalitis virus (JEV) contains a single positive-strand RNA genome nearly 11 kb in length and is not formally thought to generate subgenomic RNA molecules during replication. Here, we report the abundant accumulation of a 3'-terminal 521- to 523-nucleotide (nt) genome fragment, representing a major portion of the 585-nt 3' untranslated region, in both mammalian (BHK-21) and mosquito (C6/36) cells infected with any of nine strains of JEV. In BHK-21 cells, the viral genome was detected as early as 24 h postinfection, the small RNA was detected as early as 28 h postinfection, and the small RNA was 0.25 to 1.5 times as abundant as the genome on a molar basis between 28 and 48 h postinfection. In C6/36 cells, the genome and small RNA were present 5 days postinfection and the small RNA was 1.25 to 5.14 times as abundant as the genome. The 3'-terminal 523-nt small RNA contains a 5'-proximal stable hairpin (nt 6 to 56) that may play a role in its formation and the conserved flavivirus 3'-cyclization motif (nt 413 to 420) and the 3'-terminal long stable hairpin structure (nt 440 to 523) that have postulated roles in genome replication. Abundant accumulation of the small RNA during viral replication in both mammalian and mosquito cells suggests that it may play a biological role, perhaps as a regulator of RNA synthesis.
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Affiliation(s)
- Kuo-Chih Lin
- Department of Life Science, National Dong Hwa University, No. 1 Section 2 University Road, Shoufeng, Hualien 97401, Taiwan, Republic of China
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50
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Abstract
Resistance to flavivirus-induced disease in mice was first discovered in the 1920s and was subsequently shown to be controlled by the resistant allele of a single dominant autosomal gene. While the majority of current laboratory mouse stains have a homozygous-susceptible phenotype, the resistant allele has been found to segregate in wild mouse populations in many different parts of the world. Resistance is flavivirus specific and extends to both mosquito- and tick-borne flaviviruses. Resistant animals are infected productively by flaviviruses but produce lower virus titers, especially in their brains, as compared to susceptible mice. Decreased virus production is observed in resistant animals even during a lethal infection and the times of disease onset and death are also delayed as compared to susceptible mice. An intact immune response is required to clear flaviviruses from resistant mice. The resistant phenotype is expressed constitutively and does not require interferon induction. The Flv gene was discovered using a positional cloning approach and identified as Oas1b. Susceptible mice produce a truncated Oas1b protein. A C820T transition in the fourth exon of the gene introduced a premature stop codon and was found in all susceptible mouse strains tested. Possible mechanisms by which the product of the resistant allele could confer the resistant phenotype are discussed.
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Affiliation(s)
- Margo A Brinton
- Biology Department, Georgia State University, Atlanta, Georgia 30303, USA
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