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Utrilla-Trigo S, Jiménez-Cabello L, Marín-López A, Illescas-Amo M, Andrés G, Calvo-Pinilla E, Lorenzo G, van Rijn PA, Ortego J, Nogales A. Engineering recombinant replication-competent bluetongue viruses expressing reporter genes for in vitro and non-invasive in vivo studies. Microbiol Spectr 2024; 12:e0249323. [PMID: 38353566 PMCID: PMC10923215 DOI: 10.1128/spectrum.02493-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 12/22/2023] [Indexed: 03/06/2024] Open
Abstract
Bluetongue virus (BTV) is the causative agent of the important livestock disease bluetongue (BT), which is transmitted via Culicoides bites. BT causes severe economic losses associated with its considerable impact on health and trade of animals. By reverse genetics, we have designed and rescued reporter-expressing recombinant (r)BTV expressing NanoLuc luciferase (NLuc) or Venus fluorescent protein. To generate these viruses, we custom synthesized a modified viral segment 5 encoding NS1 protein with the reporter genes located downstream and linked by the Porcine teschovirus-1 (PTV-1) 2A autoproteolytic cleavage site. Therefore, fluorescent signal or luciferase activity is only detected after virus replication and expression of non-structural proteins. Fluorescence or luminescence signals were detected in cells infected with rBTV/Venus or rBTV/NLuc, respectively. Moreover, the marking of NS2 protein confirmed that reporter genes were only expressed in BTV-infected cells. Growth kinetics of rBTV/NLuc and rBTV/Venus in Vero cells showed replication rates similar to those of wild-type and rBTV. Infectivity studies of these recombinant viruses in IFNAR(-/-) mice showed a higher lethal dose for rBTV/NLuc and rBTV/Venus than for rBTV indicating that viruses expressing the reporter genes are attenuated in vivo. Interestingly, luciferase activity was detected in the plasma of viraemic mice infected with rBTV/NLuc. Furthermore, luciferase activity quantitatively correlated with RNAemia levels of infected mice throughout the infection. In addition, we have investigated the in vivo replication and dissemination of BTV in IFNAR (-/-) mice using BTV/NLuc and non-invasive in vivo imaging systems.IMPORTANCEThe use of replication-competent viruses that encode a traceable fluorescent or luciferase reporter protein has significantly contributed to the in vitro and in vivo study of viral infections and the development of novel therapeutic approaches. In this work, we have generated rBTV that express fluorescent or luminescence proteins to track BTV infection both in vitro and in vivo. Despite the availability of vaccines, BTV and other related orbivirus are still associated with a significant impact on animal health and have important economic consequences worldwide. Our studies may contribute to the advance in orbivirus research and pave the way for the rapid development of new treatments, including vaccines.
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Affiliation(s)
- Sergio Utrilla-Trigo
- Centro de Investigación en Sanidad Animal (CISA), Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Valdeolmos, Madrid, Spain
| | - Luis Jiménez-Cabello
- Centro de Investigación en Sanidad Animal (CISA), Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Valdeolmos, Madrid, Spain
| | - Alejandro Marín-López
- Section of Infectious Diseases, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Miguel Illescas-Amo
- Centro de Investigación en Sanidad Animal (CISA), Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Valdeolmos, Madrid, Spain
| | - Germán Andrés
- Centro de Investigación en Sanidad Animal (CISA), Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Valdeolmos, Madrid, Spain
| | - Eva Calvo-Pinilla
- Centro de Investigación en Sanidad Animal (CISA), Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Valdeolmos, Madrid, Spain
| | - Gema Lorenzo
- Centro de Investigación en Sanidad Animal (CISA), Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Valdeolmos, Madrid, Spain
| | - Piet A. van Rijn
- Department of Virology, Wageningen Bioveterinary Research (WBVR), Lelystad, the Netherlands
- Department of Biochemistry, Centre for Human Metabolomics, North-West University, Potchefstroom, South Africa
| | - Javier Ortego
- Centro de Investigación en Sanidad Animal (CISA), Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Valdeolmos, Madrid, Spain
| | - Aitor Nogales
- Centro de Investigación en Sanidad Animal (CISA), Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Valdeolmos, Madrid, Spain
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Luo Z, Liang Y, Tian M, Ruan Z, Su R, Shereen MA, Yin J, Wu K, Guo J, Zhang Q, Li Y, Wu J. Inhibition of PIKFYVE kinase interferes ESCRT pathway to suppress RNA virus replication. J Med Virol 2023; 95:e28527. [PMID: 36695658 DOI: 10.1002/jmv.28527] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 12/16/2022] [Accepted: 01/14/2023] [Indexed: 01/26/2023]
Abstract
Endosomal sorting complex required for transport (ESCRT) is essential in the functional operation of endosomal transport in envelopment and budding of enveloped RNA viruses. However, in nonenveloped RNA viruses such as enteroviruses of the Picornaviridae family, the precise function of ESCRT pathway in viral replication remains elusive. Here, we initially evaluated that the ESCRT pathway is important for viral replication upon enterovirus 71 (EV71) infection. Furthermore, we discovered that YM201636, a specific inhibitor of phosphoinositide kinase, FYVE finger containing (PIKFYVE) kinase, significantly suppressed EV71 replication and virus-induced inflammation in vitro and in vivo. Mechanistically, YM201636 inhibits PIKFYVE kinase to block the ESCRT pathway and endosomal transport, leading to the disruption of viral entry and replication complex in subcellular components and ultimately repression of intracellular RNA virus replication and virus-induced inflammatory responses. Further studies found that YM201636 broadly represses the replication of other RNA viruses, including coxsackievirus B3 (CVB3), poliovirus 1 (PV1), echovirus 11 (E11), Zika virus (ZIKV), and vesicular stomatitis virus (VSV), rather than DNA viruses, including adenovirus 3 (ADV3) and hepatitis B virus (HBV). Our findings shed light on the mechanism underlying PIKFYVE-modulated ESCRT pathway involved in RNA virus replication, and also provide a prospective antiviral therapy during RNA viruses infections.
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Affiliation(s)
- Zhen Luo
- Guangdong Provincial Key Laboratory of Virology, Institute of Medical Microbiology, Jinan University, Guangzhou, China.,Foshan Institute of Medical Microbiology, Foshan, China
| | - Yicong Liang
- Guangdong Provincial Key Laboratory of Virology, Institute of Medical Microbiology, Jinan University, Guangzhou, China
| | - Mingfu Tian
- Department of Cardiology, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Zhihui Ruan
- Guangdong Provincial Key Laboratory of Virology, Institute of Medical Microbiology, Jinan University, Guangzhou, China.,Foshan Institute of Medical Microbiology, Foshan, China
| | - Rui Su
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China.,Henan Key Laboratory of Immunology and Targeted Drug, School of Basic Medical Science, Xinxiang Medical University, Xinxiang, China
| | - Muhammad Adnan Shereen
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China.,Department of Microbiology, Kohsar University Murree, Kashmir Point, Pakistan
| | - Jialing Yin
- Guangdong Provincial Key Laboratory of Virology, Institute of Medical Microbiology, Jinan University, Guangzhou, China
| | - Kailang Wu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China
| | - Jun Guo
- Department of Cardiology, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Qiwei Zhang
- Guangdong Provincial Key Laboratory of Virology, Institute of Medical Microbiology, Jinan University, Guangzhou, China.,Foshan Institute of Medical Microbiology, Foshan, China
| | - Yongkui Li
- Guangdong Provincial Key Laboratory of Virology, Institute of Medical Microbiology, Jinan University, Guangzhou, China.,Foshan Institute of Medical Microbiology, Foshan, China
| | - Jianguo Wu
- Guangdong Provincial Key Laboratory of Virology, Institute of Medical Microbiology, Jinan University, Guangzhou, China.,Foshan Institute of Medical Microbiology, Foshan, China.,Department of Cardiology, The First Affiliated Hospital of Jinan University, Guangzhou, China.,State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, China
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3
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Vaccination as a Strategy to Prevent Bluetongue Virus Vertical Transmission. Pathogens 2021; 10:pathogens10111528. [PMID: 34832683 PMCID: PMC8622840 DOI: 10.3390/pathogens10111528] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 11/13/2021] [Accepted: 11/19/2021] [Indexed: 11/17/2022] Open
Abstract
Bluetongue virus (BTV) produces an economically important disease in ruminants of compulsory notification to the OIE. BTV is typically transmitted by the bite of Culicoides spp., however, some BTV strains can be transmitted vertically, and this is associated with fetus malformations and abortions. The viral factors associated with the virus potency to cross the placental barrier are not well defined. The potency of vertical transmission is retained and sometimes even increased in live attenuated BTV vaccine strains. Because BTV possesses a segmented genome, the possibility of reassortment of vaccination strains with wild-type virus could even favor the transmission of this phenotype. In the present review, we will describe the non-vector-based BTV infection routes and discuss the experimental vaccination strategies that offer advantages over this drawback of some live attenuated BTV vaccines.
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The Interplay between Bluetongue Virus Infections and Adaptive Immunity. Viruses 2021; 13:v13081511. [PMID: 34452376 PMCID: PMC8402766 DOI: 10.3390/v13081511] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Revised: 07/19/2021] [Accepted: 07/28/2021] [Indexed: 12/18/2022] Open
Abstract
Viral infections have long provided a platform to understand the workings of immunity. For instance, great strides towards defining basic immunology concepts, such as MHC restriction of antigen presentation or T-cell memory development and maintenance, have been achieved thanks to the study of lymphocytic choriomeningitis virus (LCMV) infections. These studies have also shaped our understanding of antiviral immunity, and in particular T-cell responses. In the present review, we discuss how bluetongue virus (BTV), an economically important arbovirus from the Reoviridae family that affects ruminants, affects adaptive immunity in the natural hosts. During the initial stages of infection, BTV triggers leucopenia in the hosts. The host then mounts an adaptive immune response that controls the disease. In this work, we discuss how BTV triggers CD8+ T-cell expansion and neutralizing antibody responses, yet in some individuals viremia remains detectable after these adaptive immune mechanisms are active. We present some unpublished data showing that BTV infection also affects other T cell populations such as CD4+ T-cells or γδ T-cells, as well as B-cell numbers in the periphery. This review also discusses how BTV evades these adaptive immune mechanisms so that it can be transmitted back to the arthropod host. Understanding the interaction of BTV with immunity could ultimately define the correlates of protection with immune mechanisms that would improve our knowledge of ruminant immunology.
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Rojas JM, Avia M, Martín V, Sevilla N. Inhibition of the IFN Response by Bluetongue Virus: The Story So Far. Front Microbiol 2021; 12:692069. [PMID: 34168637 PMCID: PMC8217435 DOI: 10.3389/fmicb.2021.692069] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 05/17/2021] [Indexed: 11/13/2022] Open
Abstract
Bluetongue virus (BTV) is the prototypical orbivirus that belongs to the Reoviridae family. BTV infection produces a disease in ruminants, particularly in sheep, that results in economic losses through reduced productivity. BTV is transmitted by the bite of Culicoides spp. midges and is nowadays distributed globally throughout subtropical and even temperate regions. As most viruses, BTV is susceptible to the IFN response, the first line of defense employed by the immune system to combat viral infections. In turn, BTV has evolved strategies to counter the IFN response and promote its replication. The present review we will revise the works describing how BTV interferes with the IFN response.
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Affiliation(s)
- José Manuel Rojas
- Centro de Investigación en Sanidad Animal (CISA-INIA), Centro Nacional Instituto de Investigación y Tecnología Agraria y Alimentaria, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Miguel Avia
- Centro de Investigación en Sanidad Animal (CISA-INIA), Centro Nacional Instituto de Investigación y Tecnología Agraria y Alimentaria, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Verónica Martín
- Centro de Investigación en Sanidad Animal (CISA-INIA), Centro Nacional Instituto de Investigación y Tecnología Agraria y Alimentaria, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Noemí Sevilla
- Centro de Investigación en Sanidad Animal (CISA-INIA), Centro Nacional Instituto de Investigación y Tecnología Agraria y Alimentaria, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
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Cuesta SA, Reinoso C, Morales F, Pilaquinga F, Morán-Marcillo G, Proaño-Bolaños C, Blasco-Zúñiga A, Rivera M, Meneses L. Novel antimicrobial cruzioseptin peptides extracted from the splendid leaf frog, Cruziohyla calcarifer. Amino Acids 2021; 53:853-868. [PMID: 33942149 DOI: 10.1007/s00726-021-02986-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 04/21/2021] [Indexed: 11/25/2022]
Abstract
Antimicrobial peptides (AMPs) constitute part of a broad range of bioactive compounds present on diverse organisms, including frogs. Peptides, produced in the granular glands of amphibian skin, constitute a component of their innate immune response, providing protection against pathogenic microorganisms. In this work, two novel cruzioseptins peptides, cruzioseptin-16 and -17, extracted from the splendid leaf frog Cruziohyla calcarifer are presented. These peptides were identified using molecular cloning and tandem mass spectrometry. Later, peptides were synthetized using solid-phase peptide synthesis, and their minimal inhibitory concentration and haemolytic activity were tested. Furthermore, these two cruzioseptins plus three previously reported (CZS-1, CZS-2, CZS-3) were computationally characterized. Results show that cruzioseptins are 21-23 residues long alpha helical cationic peptides, with antimicrobial activity against E. coli, S. aureus, and C. albicans and low haemolytic effect. Docking results agree with the principal action mechanism of cationic AMPs that goes through cell membrane disruption due to electrostatic interactions between cationic residues in the cruzioseptins and negative phosphate groups in the pathogen cell membrane. An action mechanism through enzymes inhibition was also tried, but no conclusive results about this mechanism were obtained.
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Affiliation(s)
- Sebastian A Cuesta
- Laboratorio de Química Computacional, Escuela de Ciencias Químicas, Facultad de Ciencias Exactas y Naturales, Pontificia Universidad Católica del Ecuador, Av. 12 de octubre 1076 Apartado: 17-01-2184, Quito, Ecuador
| | - Camila Reinoso
- Laboratorio de Química Computacional, Escuela de Ciencias Químicas, Facultad de Ciencias Exactas y Naturales, Pontificia Universidad Católica del Ecuador, Av. 12 de octubre 1076 Apartado: 17-01-2184, Quito, Ecuador
| | - Felipe Morales
- Laboratorio de Química Computacional, Escuela de Ciencias Químicas, Facultad de Ciencias Exactas y Naturales, Pontificia Universidad Católica del Ecuador, Av. 12 de octubre 1076 Apartado: 17-01-2184, Quito, Ecuador
| | - Fernanda Pilaquinga
- Laboratorio de Química Computacional, Escuela de Ciencias Químicas, Facultad de Ciencias Exactas y Naturales, Pontificia Universidad Católica del Ecuador, Av. 12 de octubre 1076 Apartado: 17-01-2184, Quito, Ecuador
| | - Giovanna Morán-Marcillo
- Laboratory of Molecular Biology and Biochemistry, Biomolecules Discovery Group, Universidad Regional Amazónica Ikiam, Km 7 ½ vía Muyuna, 150150, Tena, Ecuador
| | - Carolina Proaño-Bolaños
- Laboratory of Molecular Biology and Biochemistry, Biomolecules Discovery Group, Universidad Regional Amazónica Ikiam, Km 7 ½ vía Muyuna, 150150, Tena, Ecuador
- Natural Drug Discovery Group, School of Pharmacy, Queen's University Belfast, 97 Lisburn Road, BT9 7BL, Belfast, Northern Ireland, UK
| | - Ailín Blasco-Zúñiga
- Laboratorio de Investigación en Citogenética y Biomoléculas de Anfibios (LICBA), Facultad de Ciencias Exactas y Naturales, Centro de Investigación para la Salud en América Latina-CISeAL, Pontificia Universidad Católica del Ecuador, Av. 12 de octubre 1076 Apartado: 17-01-2184, Quito, Ecuador
- Dirección Nacional de Biodiversidad, Ministerio del Ambiente del Ecuador, Madrid 1159 y Andalucía, Quito, Ecuador
| | - Miryan Rivera
- Laboratorio de Investigación en Citogenética y Biomoléculas de Anfibios (LICBA), Facultad de Ciencias Exactas y Naturales, Centro de Investigación para la Salud en América Latina-CISeAL, Pontificia Universidad Católica del Ecuador, Av. 12 de octubre 1076 Apartado: 17-01-2184, Quito, Ecuador
| | - Lorena Meneses
- Laboratorio de Química Computacional, Escuela de Ciencias Químicas, Facultad de Ciencias Exactas y Naturales, Pontificia Universidad Católica del Ecuador, Av. 12 de octubre 1076 Apartado: 17-01-2184, Quito, Ecuador.
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Labadie T, Roy P. A non-enveloped arbovirus released in lysosome-derived extracellular vesicles induces super-infection exclusion. PLoS Pathog 2020; 16:e1009015. [PMID: 33075107 PMCID: PMC7595637 DOI: 10.1371/journal.ppat.1009015] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 10/29/2020] [Accepted: 09/25/2020] [Indexed: 12/11/2022] Open
Abstract
Recent developments on extracellular vesicles (EVs) containing multiple virus particles challenge the rigid definition of non-enveloped viruses. However, how non-enveloped viruses hijack cell machinery to promote non-lytic release in EVs, and their functional roles, remain to be clarified. Here we used Bluetongue virus (BTV) as a model of a non-enveloped arthropod-borne virus and discovered that the majority of viruses are released in EVs. Based on the cellular proteins detected in these EVs, and use of inhibitors targeting the cellular degradation process, we demonstrated that these extracellular vesicles are derived from secretory lysosomes, in which the acidic pH is neutralized upon the infection. Moreover, we report that secreted EVs are more efficient than free-viruses for initiating infections, but that they trigger super-infection exclusion that only free-viruses can overcome.
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Affiliation(s)
- Thomas Labadie
- Department of Pathogen Molecular Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, United Kingdom
| | - Polly Roy
- Department of Pathogen Molecular Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, United Kingdom
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Roy P. Bluetongue virus assembly and exit pathways. Adv Virus Res 2020; 108:249-273. [PMID: 33837718 DOI: 10.1016/bs.aivir.2020.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Bluetongue virus (BTV) is an insect-vectored emerging pathogen of wild ruminants and livestock in many parts of the world. The virion particle is a complex structure of consecutive layers of protein surrounding a genome of 10 double-stranded (ds) RNA segments. BTV has been studied extensively as a model system for large, nonenveloped dsRNA viruses. A combination of recombinant proteins and particles together with reverse genetics, high-resolution structural analysis by X-ray crystallography and cryo-electron microscopy techniques have been utilized to provide an order for the assembly of the capsid shell and the protein sequestration required for it. Further, a reconstituted in vitro assembly system and RNA-RNA interaction assay, have defined the individual steps required for the assembly and packaging of the 10-segmented RNA genome. In addition, various microscopic techniques have been utilized to illuminate the stages of virus maturation and its egress via multiple pathways. These findings have not only given an overall understanding of BTV assembly and morphogenesis but also indicated that similar assembly and egress pathways are likely to be used by related viruses and provided an informed starting point for intervention or prevention.
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Affiliation(s)
- Polly Roy
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom.
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Labadie T, Sullivan E, Roy P. Multiple Routes of Bluetongue Virus Egress. Microorganisms 2020; 8:E965. [PMID: 32605099 PMCID: PMC7409164 DOI: 10.3390/microorganisms8070965] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 06/18/2020] [Accepted: 06/25/2020] [Indexed: 12/20/2022] Open
Abstract
Bluetongue virus (BTV) is an arthropod-borne virus infecting livestock. Its frequent emergence in Europe and North America had caused significant agricultural and economic loss. BTV is also of scientific interest as a model to understand the mechanisms underlying non-enveloped virus release from mammalian and insect cells. The BTV particle, which is formed of a complex double-layered capsid, was first considered as a lytic virus that needs to lyse the infected cells for cell to cell transmission. In the last decade, however, a more in-depth focus on the role of the non-structural proteins has led to several examples where BTV particles are also released through different budding mechanisms at the plasma membrane. It is now clear that the non-structural protein NS3 is the main driver of BTV release, via different interactions with both viral and cellular proteins of the cell sorting and exocytosis pathway. In this review, we discuss the most recent advances in the molecular biology of BTV egress and compare the mechanisms that lead to lytic or non-lytic BTV release.
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Affiliation(s)
| | | | - Polly Roy
- Department of Pathogen Molecular Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, WC1E 7HT, London WC1E 7HT, UK; (T.L.); (E.S.)
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Differential Localization of Structural and Non-Structural Proteins during the Bluetongue Virus Replication Cycle. Viruses 2020; 12:v12030343. [PMID: 32245145 PMCID: PMC7150864 DOI: 10.3390/v12030343] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 03/13/2020] [Accepted: 03/19/2020] [Indexed: 12/12/2022] Open
Abstract
Members of the Reoviridae family assemble virus factories within the cytoplasm of infected cells to replicate and assemble virus particles. Bluetongue virus (BTV) forms virus inclusion bodies (VIBs) that are aggregates of viral RNA, certain viral proteins, and host factors, and have been shown to be sites of the initial assembly of transcriptionally active virus-like particles. This study sought to characterize the formation, composition, and ultrastructure of VIBs, particularly in relation to virus replication. In this study we have utilized various microscopic techniques, including structured illumination microscopy, and virological assays to show for the first time that the outer capsid protein VP5, which is essential for virus maturation, is also associated with VIBs. The addition of VP5 to assembled virus cores exiting VIBs is required to arrest transcriptionally active core particles, facilitating virus maturation. Furthermore, we observed a time-dependent association of the glycosylated non-structural protein 3 (NS3) with VIBs, and report on the importance of the two polybasic motifs within NS3 that facilitate virus trafficking and egress from infected cells at the plasma membrane. Thus, the presence of VP5 and the dynamic nature of NS3 association with VIBs that we report here provide novel insight into these previously less well-characterized processes.
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