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Loterio RK, Monson EA, Templin R, de Bruyne JT, Flores HA, Mackenzie JM, Ramm G, Helbig KJ, Simmons CP, Fraser JE. Antiviral Wolbachia strains associate with Aedes aegypti endoplasmic reticulum membranes and induce lipid droplet formation to restrict dengue virus replication. mBio 2024; 15:e0249523. [PMID: 38132636 PMCID: PMC10865983 DOI: 10.1128/mbio.02495-23] [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: 09/13/2023] [Accepted: 11/20/2023] [Indexed: 12/23/2023] Open
Abstract
Wolbachia are a genus of insect endosymbiotic bacteria which includes strains wMel and wAlbB that are being utilized as a biocontrol tool to reduce the incidence of Aedes aegypti-transmitted viral diseases like dengue. However, the precise mechanisms underpinning the antiviral activity of these Wolbachia strains are not well defined. Here, we generated a panel of Ae. aegypti-derived cell lines infected with antiviral strains wMel and wAlbB or the non-antiviral Wolbachia strain wPip to understand host cell morphological changes specifically induced by antiviral strains. Antiviral strains were frequently found to be entirely wrapped by the host endoplasmic reticulum (ER) membrane, while wPip bacteria clustered separately in the host cell cytoplasm. ER-derived lipid droplets (LDs) increased in volume in wMel- and wAlbB-infected cell lines and mosquito tissues compared to cells infected with wPip or Wolbachia-free controls. Inhibition of fatty acid synthase (required for triacylglycerol biosynthesis) reduced LD formation and significantly restored ER-associated dengue virus replication in cells occupied by wMel. Together, this suggests that antiviral Wolbachia strains may specifically alter the lipid composition of the ER to preclude the establishment of dengue virus (DENV) replication complexes. Defining Wolbachia's antiviral mechanisms will support the application and longevity of this effective biocontrol tool that is already being used at scale.IMPORTANCEAedes aegypti transmits a range of important human pathogenic viruses like dengue. However, infection of Ae. aegypti with the insect endosymbiotic bacterium, Wolbachia, reduces the risk of mosquito to human viral transmission. Wolbachia is being utilized at field sites across more than 13 countries to reduce the incidence of viruses like dengue, but it is not well understood how Wolbachia induces its antiviral effects. To examine this at the subcellular level, we compared how different strains of Wolbachia with varying antiviral strengths associate with and modify host cell structures. Strongly antiviral strains were found to specifically associate with the host endoplasmic reticulum and induce striking impacts on host cell lipid droplets. Inhibiting Wolbachia-induced lipid redistribution partially restored dengue virus replication demonstrating this is a contributing role for Wolbachia's antiviral activity. These findings provide new insights into how antiviral Wolbachia strains associate with and modify Ae. aegypti host cells.
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Affiliation(s)
- Robson K. Loterio
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, Australia
| | - Ebony A. Monson
- Department of Microbiology, Anatomy, Physiology and Pharmacology; School of Agriculture, Biomedicine and Environment, La Trobe University, Melbourne, Australia
| | - Rachel Templin
- Ramaciotti Centre For Cryo-Electron Microscopy, Monash University, Clayton, Australia
| | | | - Heather A. Flores
- School of Biological Sciences, Monash University, Clayton, Australia
| | - Jason M. Mackenzie
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Australia
| | - Georg Ramm
- Ramaciotti Centre For Cryo-Electron Microscopy, Monash University, Clayton, Australia
| | - Karla J. Helbig
- Department of Microbiology, Anatomy, Physiology and Pharmacology; School of Agriculture, Biomedicine and Environment, La Trobe University, Melbourne, Australia
| | - Cameron P. Simmons
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, Australia
- World Mosquito Program, Monash University, Clayton, Australia
| | - Johanna E. Fraser
- Department of Microbiology, Biomedicine Discovery Institute, Monash University, Clayton, Australia
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2
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Tan BEK, Beard MR, Eyre NS. Identification of Key Residues in Dengue Virus NS1 Protein That Are Essential for Its Secretion. Viruses 2023; 15:v15051102. [PMID: 37243188 DOI: 10.3390/v15051102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 04/21/2023] [Accepted: 04/25/2023] [Indexed: 05/28/2023] Open
Abstract
Dengue virus (DENV) non-structural protein 1 (NS1) is involved in multiple aspects of the DENV lifecycle. Importantly, it is secreted from infected cells as a hexameric lipoparticle that mediates vascular damage that is a hallmark of severe dengue. Although the secretion of NS1 is known to be important in DENV pathogenesis, the exact molecular features of NS1 that are required for its secretion from cells are not fully understood. In this study, we employed random point mutagenesis in the context of an NS1 expression vector encoding a C-terminal HiBiT luminescent peptide tag to identify residues within NS1 that are essential for its secretion. Using this approach, we identified 10 point mutations that corresponded with impaired NS1 secretion, with in silico analyses indicating that the majority of these mutations are located within the β-ladder domain. Additional studies on two of these mutants, V220D and A248V, revealed that they prevented viral RNA replication, while studies using a DENV NS1-NS5 viral polyprotein expression system demonstrated that these mutations resulted in a more reticular NS1 localisation pattern and failure to detect mature NS1 at its predicted molecular weight by Western blotting using a conformation-specific monoclonal antibody. Together, these studies demonstrate that the combination of a luminescent peptide tagged NS1 expression system with random point mutagenesis enables rapid identification of mutations that alter NS1 secretion. Two such mutations identified via this approach revealed residues that are essential for correct NS1 processing or maturation and viral RNA replication.
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Affiliation(s)
- Brandon E K Tan
- Research Centre of Infectious Diseases, School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Michael R Beard
- Research Centre of Infectious Diseases, School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Nicholas S Eyre
- College of Medicine and Public Health (CMPH), Flinders University, Bedford Park, SA 5042, Australia
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3
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Li J, Yan X, Li B, Huang L, Wang X, He B, Xie H, Wu Q, Chen L. Identification and validation of ferroptosis-related genes in patients infected with dengue virus: implication in the pathogenesis of DENV. Virus Genes 2023; 59:377-390. [PMID: 36973608 PMCID: PMC10042429 DOI: 10.1007/s11262-023-01985-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Accepted: 02/22/2023] [Indexed: 03/29/2023]
Abstract
Ferroptosis, an iron-dependent form of regulated cell death, has been associated with many virus infections. However, the role of ferroptosis in dengue virus (DENV) infection remains to be clarified. In our study, a dengue fever microarray dataset (GSE51808) of whole blood samples was downloaded from the Gene Expression Omnibus (GEO), and a list of ferroptosis related genes (FRGs) was extracted from the FerrDb. We identified 37 ferroptosis-related differentially expressed genes (FR-DEGs) in DENV-infected patient blood samples compared to healthy individuals. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses as well as protein-protein interaction (PPI) network of FR-DEGs revealed that these 37 FR-DEGs were mainly related to the C-type lectin receptor and p53 signaling pathway. Nine out of the 37 FR-DEGs (HSPA5, CAV1, HRAS, PTGS2, JUN, IL6, ATF3, XBP1, and CDKN2A) were hub genes, of which 5 were validated by qRT-PCR in DENV-infected HepG2 cells. Finally, using miRNA-mRNA regulatory network, we identified has-miR-124-3p and has-miR-16-5p as the most critical miRNAs in regulating the expression of these hub genes. In conclusion, our findings demonstrated that 5 FR-DEGs, JUN, IL6, ATF3, XBP1, and CDKN2A, and two miRNAs, has-miR-124-3p and has-miR-16-5p may implicate an essential role of ferroptosis in DENV infection, and further studies are warranted to explore the underlying mechanisms.
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Affiliation(s)
- Jinlian Li
- The Joint Laboratory on Transfusion-Transmitted Diseases (TTDs) Between Institute of Blood Transfusion, Chinese Academy of Medical Sciences and Nanning Blood Center, Nanning Blood Center, Nanning, China
| | - Xipeng Yan
- The Joint Laboratory on Transfusion-Transmitted Diseases (TTDs) Between Institute of Blood Transfusion, Chinese Academy of Medical Sciences and Nanning Blood Center, Nanning Blood Center, Nanning, China
| | - Bin Li
- The Joint Laboratory on Transfusion-Transmitted Diseases (TTDs) Between Institute of Blood Transfusion, Chinese Academy of Medical Sciences and Nanning Blood Center, Nanning Blood Center, Nanning, China
| | - Linbing Huang
- The Joint Laboratory on Transfusion-Transmitted Diseases (TTDs) Between Institute of Blood Transfusion, Chinese Academy of Medical Sciences and Nanning Blood Center, Nanning Blood Center, Nanning, China
| | - Xinwei Wang
- The Joint Laboratory on Transfusion-Transmitted Diseases (TTDs) Between Institute of Blood Transfusion, Chinese Academy of Medical Sciences and Nanning Blood Center, Nanning Blood Center, Nanning, China
| | - Baoren He
- The Joint Laboratory on Transfusion-Transmitted Diseases (TTDs) Between Institute of Blood Transfusion, Chinese Academy of Medical Sciences and Nanning Blood Center, Nanning Blood Center, Nanning, China
| | - He Xie
- The Hospital of Xidian Group, Xi'an, China
| | - Qunying Wu
- School of Intelligent Medicine and Biotechnology, Guilin Medical University, Guilin, China.
| | - Limin Chen
- The Joint Laboratory on Transfusion-Transmitted Diseases (TTDs) Between Institute of Blood Transfusion, Chinese Academy of Medical Sciences and Nanning Blood Center, Nanning Blood Center, Nanning, China.
- The Hospital of Xidian Group, Xi'an, China.
- Institute of Blood Transfusion, Chinese Academy of Medical Sciences and Peking Union Medical College, Chengdu, China.
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4
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Schor S, Pu S, Nicolaescu V, Azari S, Kõivomägi M, Karim M, Cassonnet P, Saul S, Neveu G, Yueh A, Demeret C, Skotheim JM, Jacob Y, Randall G, Einav S. The cargo adapter protein CLINT1 is phosphorylated by the Numb-associated kinase BIKE and mediates dengue virus infection. J Biol Chem 2022; 298:101956. [PMID: 35452674 PMCID: PMC9133654 DOI: 10.1016/j.jbc.2022.101956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 03/22/2022] [Accepted: 03/24/2022] [Indexed: 11/25/2022] Open
Abstract
The signaling pathways and cellular functions regulated by the four Numb-associated kinases are largely unknown. We reported that AAK1 and GAK control intracellular trafficking of RNA viruses and revealed a requirement for BIKE in early and late stages of dengue virus (DENV) infection. However, the downstream targets phosphorylated by BIKE have not yet been identified. Here, to identify BIKE substrates, we conducted a barcode fusion genetics-yeast two-hybrid screen and retrieved publicly available data generated via affinity-purification mass spectrometry. We subsequently validated 19 of 47 putative BIKE interactors using mammalian cell-based protein-protein interaction assays. We found that CLINT1, a cargo-specific adapter implicated in bidirectional Golgi-to-endosome trafficking, emerged as a predominant hit in both screens. Our experiments indicated that BIKE catalyzes phosphorylation of a threonine 294 CLINT1 residue both in vitro and in cell culture. Our findings revealed that CLINT1 phosphorylation mediates its binding to the DENV nonstructural 3 protein and subsequently promotes DENV assembly and egress. Additionally, using live-cell imaging we revealed that CLINT1 cotraffics with DENV particles and is involved in mediating BIKE's role in DENV infection. Finally, our data suggest that additional cellular BIKE interactors implicated in the host immune and stress responses and the ubiquitin proteasome system might also be candidate phosphorylation substrates of BIKE. In conclusion, these findings reveal cellular substrates and pathways regulated by the understudied Numb-associated kinase enzyme BIKE, a mechanism for CLINT1 regulation, and control of DENV infection via BIKE signaling, with potential implications for cell biology, virology, and host-targeted antiviral design.
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Affiliation(s)
- Stanford Schor
- Department of Medicine, Division of Infectious Diseases and Geographic Medicine, and Department of Microbiology and Immunology, Stanford University, California, USA
| | - Szuyuan Pu
- Department of Medicine, Division of Infectious Diseases and Geographic Medicine, and Department of Microbiology and Immunology, Stanford University, California, USA
| | - Vlad Nicolaescu
- Department of Microbiology, University of Chicago, Chicago, Illinois, USA
| | - Siavash Azari
- Department of Medicine, Division of Infectious Diseases and Geographic Medicine, and Department of Microbiology and Immunology, Stanford University, California, USA
| | | | - Marwah Karim
- Department of Medicine, Division of Infectious Diseases and Geographic Medicine, and Department of Microbiology and Immunology, Stanford University, California, USA
| | - Patricia Cassonnet
- Department of Virology, Molecular Genetics of RNA Virus Genetics (GMVR), Pasteur Institute, National Center for Scientific Research, and Paris Diderot University, Paris, France
| | - Sirle Saul
- Department of Medicine, Division of Infectious Diseases and Geographic Medicine, and Department of Microbiology and Immunology, Stanford University, California, USA
| | - Gregory Neveu
- Department of Medicine, Division of Infectious Diseases and Geographic Medicine, and Department of Microbiology and Immunology, Stanford University, California, USA
| | - Andrew Yueh
- Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Zhunan, Taiwan
| | - Caroline Demeret
- Department of Virology, Molecular Genetics of RNA Virus Genetics (GMVR), Pasteur Institute, National Center for Scientific Research, and Paris Diderot University, Paris, France
| | - Jan M Skotheim
- Department of Biology, Stanford University, California, USA
| | - Yves Jacob
- Department of Virology, Molecular Genetics of RNA Virus Genetics (GMVR), Pasteur Institute, National Center for Scientific Research, and Paris Diderot University, Paris, France
| | - Glenn Randall
- Department of Microbiology, University of Chicago, Chicago, Illinois, USA
| | - Shirit Einav
- Department of Medicine, Division of Infectious Diseases and Geographic Medicine, and Department of Microbiology and Immunology, Stanford University, California, USA; Chan Zuckerberg Biohub, San Francisco, California, USA.
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5
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Blahove MR, Carter JR. Flavivirus Persistence in Wildlife Populations. Viruses 2021; 13:v13102099. [PMID: 34696529 PMCID: PMC8541186 DOI: 10.3390/v13102099] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 10/01/2021] [Accepted: 10/08/2021] [Indexed: 12/14/2022] Open
Abstract
A substantial number of humans are at risk for infection by vector-borne flaviviruses, resulting in considerable morbidity and mortality worldwide. These viruses also infect wildlife at a considerable rate, persistently cycling between ticks/mosquitoes and small mammals and reptiles and non-human primates and humans. Substantially increasing evidence of viral persistence in wildlife continues to be reported. In addition to in humans, viral persistence has been shown to establish in mammalian, reptile, arachnid, and mosquito systems, as well as insect cell lines. Although a considerable amount of research has centered on the potential roles of defective virus particles, autophagy and/or apoptosis-induced evasion of the immune response, and the precise mechanism of these features in flavivirus persistence have yet to be elucidated. In this review, we present findings that aid in understanding how vector-borne flavivirus persistence is established in wildlife. Research studies to be discussed include determining the critical roles universal flavivirus non-structural proteins played in flaviviral persistence, the advancement of animal models of viral persistence, and studying host factors that allow vector-borne flavivirus replication without destructive effects on infected cells. These findings underscore the viral–host relationships in wildlife animals and could be used to elucidate the underlying mechanisms responsible for the establishment of viral persistence in these animals.
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6
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Genome-wide CRISPR screen identifies RACK1 as a critical host factor for flavivirus replication. J Virol 2021; 95:e0059621. [PMID: 34586867 PMCID: PMC8610583 DOI: 10.1128/jvi.00596-21] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Cellular factors have important roles in all facets of the flavivirus replication cycle. Deciphering viral-host protein interactions is essential for understanding the flavivirus lifecycle as well as development of effective antiviral strategies. To uncover novel host factors that are co-opted by multiple flaviviruses, a CRISPR/Cas9 genome wide knockout (KO) screen was employed to identify genes required for replication of Zika virus (ZIKV). Receptor for Activated Protein C Kinase 1 (RACK1) was identified as a novel host factor required for ZIKV replication, which was confirmed via complementary experiments. Depletion of RACK1 via siRNA demonstrated that RACK1 is important for replication of a wide range of mosquito- and tick-borne flaviviruses, including West Nile Virus (WNV), Dengue Virus (DENV), Powassan Virus (POWV) and Langat Virus (LGTV) as well as the coronavirus SARS-CoV-2, but not for YFV, EBOV, VSV or HSV. Notably, flavivirus replication was only abrogated when RACK1 expression was dampened prior to infection. Utilising a non-replicative flavivirus model, we show altered morphology of viral replication factories and reduced formation of vesicle packets (VPs) in cells lacking RACK1 expression. In addition, RACK1 interacted with NS1 protein from multiple flaviviruses; a key protein for replication complex formation. Overall, these findings reveal RACK1's crucial role to the biogenesis of pan-flavivirus replication organelles. Importance Cellular factors are critical in all facets of viral lifecycles, where overlapping interactions between the virus and host can be exploited as possible avenues for the development of antiviral therapeutics. Using a genome-wide CRISPR knock-out screening approach to identify novel cellular factors important for flavivirus replication we identified RACK1 as a pro-viral host factor for both mosquito- and tick-borne flaviviruses in addition to SARS-CoV-2. Using an innovative flavivirus protein expression system, we demonstrate for the first time the impact of the loss of RACK1 on the formation of viral replication factories known as 'vesicle packets' (VPs). In addition, we show that RACK1 can interact with numerous flavivirus NS1 proteins as a potential mechanism by which VP formation can be induced by the former.
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7
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Burton TD, Eyre NS. Applications of Deep Mutational Scanning in Virology. Viruses 2021; 13:1020. [PMID: 34071591 PMCID: PMC8227372 DOI: 10.3390/v13061020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 05/26/2021] [Accepted: 05/26/2021] [Indexed: 12/20/2022] Open
Abstract
Several recently developed high-throughput techniques have changed the field of molecular virology. For example, proteomics studies reveal complete interactomes of a viral protein, genome-wide CRISPR knockout and activation screens probe the importance of every single human gene in aiding or fighting a virus, and ChIP-seq experiments reveal genome-wide epigenetic changes in response to infection. Deep mutational scanning is a relatively novel form of protein science which allows the in-depth functional analysis of every nucleotide within a viral gene or genome, revealing regions of importance, flexibility, and mutational potential. In this review, we discuss the application of this technique to RNA viruses including members of the Flaviviridae family, Influenza A Virus and Severe Acute Respiratory Syndrome Coronavirus 2. We also briefly discuss the reverse genetics systems which allow for analysis of viral replication cycles, next-generation sequencing technologies and the bioinformatics tools that facilitate this research.
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Affiliation(s)
| | - Nicholas S. Eyre
- College of Medicine and Public Health, Flinders University, Bedford Park, SA 5042, Australia;
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8
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Zapatero-Belinchón FJ, Carriquí-Madroñal B, Gerold G. Proximity labeling approaches to study protein complexes during virus infection. Adv Virus Res 2021; 109:63-104. [PMID: 33934830 DOI: 10.1016/bs.aivir.2021.02.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Cellular compartmentalization of proteins and protein complex formation allow cells to tightly control biological processes. Therefore, understanding the subcellular localization and interactions of a specific protein is crucial to uncover its biological function. The advent of proximity labeling (PL) has reshaped cellular proteomics in infection biology. PL utilizes a genetically modified enzyme that generates a "labeling cloud" by covalently labeling proteins in close proximity to the enzyme. Fusion of a PL enzyme to a specific antibody or a "bait" protein of interest in combination with affinity enrichment mass spectrometry (AE-MS) enables the isolation and identification of the cellular proximity proteome, or proxisome. This powerful methodology has been paramount for the mapping of membrane or membraneless organelles as well as for the understanding of hard-to-purify protein complexes, such as those of transmembrane proteins. Unsurprisingly, more and more infection biology research groups have recognized the potential of PL for the identification of host-pathogen interactions. In this chapter, we introduce the enzymes commonly used for PL labeling as well as recent promising advancements and summarize the major achievements in organelle mapping and nucleic acid PL. Moreover, we comprehensively describe the research on host-pathogen interactions using PL, giving special attention to studies in the field of virology.
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Affiliation(s)
- Francisco José Zapatero-Belinchón
- Department of Biochemistry & Research Center for Emerging Infections and Zoonoses (RIZ), University of Veterinary Medicine Hannover, Hannover, Germany; Institute for Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, a Joint Venture Between the Medical School Hannover and the Helmholtz Centre for Infection Research, Hannover, Germany; Department of Clinical Microbiology, Virology, Umeå University, Umeå, Sweden; Wallenberg Centre for Molecular Medicine (WCMM), Umeå University, Umeå, Sweden.
| | - Belén Carriquí-Madroñal
- Department of Biochemistry & Research Center for Emerging Infections and Zoonoses (RIZ), University of Veterinary Medicine Hannover, Hannover, Germany; Institute for Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, a Joint Venture Between the Medical School Hannover and the Helmholtz Centre for Infection Research, Hannover, Germany
| | - Gisa Gerold
- Department of Biochemistry & Research Center for Emerging Infections and Zoonoses (RIZ), University of Veterinary Medicine Hannover, Hannover, Germany; Institute for Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, a Joint Venture Between the Medical School Hannover and the Helmholtz Centre for Infection Research, Hannover, Germany; Department of Clinical Microbiology, Virology, Umeå University, Umeå, Sweden; Wallenberg Centre for Molecular Medicine (WCMM), Umeå University, Umeå, Sweden.
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9
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Syzdykova LR, Binke S, Keyer VV, Shevtsov AB, Zaripov MM, Zhylkibayev AA, Ramanculov EM, Shustov AV. Fluorescent tagging the NS1 protein in yellow fever virus: Replication-capable viruses which produce the secretory GFP-NS1 fusion protein. Virus Res 2020; 294:198291. [PMID: 33388393 DOI: 10.1016/j.virusres.2020.198291] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 11/18/2020] [Accepted: 12/25/2020] [Indexed: 12/29/2022]
Abstract
Yellow fever virus, the prototype in the genus Flavivirus, was used to develop viruses in which the nonstructural protein NS1 is genetically fused to GFP in the context of viruses capable of autonomous replication. The GFP-tagging of NS1 at the amino-terminus appeared possible despite the presence of a small and functionally important domain at the NS1's amino-terminus which can be distorted by such fusing. GFP-tagged NS1 viruses were rescued from DNA-launched molecular clones. The initially produced GFP-tagged NS1 virus was capable of only poor replication. Sequential passages of the virus in cell cultures resulted in the appearance of mutations in GFP, NS4A, NS4B and NS5. The mutations which change amino acid sequences of GFP, NS4A and NS5 have the adaptive effect on the replication of GFP-tagged NS1 viruses. The pattern of GFP-fluorescence indicates that the GFP-NS1 fusion protein is produced into the endoplasmic reticulum. The intracellular GFP-NS1 fusion protein colocalizes with dsRNA. The discovered forms of extracellular GFP-NS1 possibly include tetramers and hexamers.
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Affiliation(s)
- Laura R Syzdykova
- National Center for Biotechnology, Korgalzhin Hwy 13/5, 010000, Nur-Sultan, Kazakhstan.
| | - Stephan Binke
- National Center for Biotechnology, Korgalzhin Hwy 13/5, 010000, Nur-Sultan, Kazakhstan.
| | - Viktoriya V Keyer
- National Center for Biotechnology, Korgalzhin Hwy 13/5, 010000, Nur-Sultan, Kazakhstan.
| | - Alexandr B Shevtsov
- National Center for Biotechnology, Korgalzhin Hwy 13/5, 010000, Nur-Sultan, Kazakhstan.
| | - Mikhail M Zaripov
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, 142290, Pushchino, Russian Federation.
| | | | - Erlan M Ramanculov
- National Center for Biotechnology, Korgalzhin Hwy 13/5, 010000, Nur-Sultan, Kazakhstan.
| | - Alexandr V Shustov
- National Center for Biotechnology, Korgalzhin Hwy 13/5, 010000, Nur-Sultan, Kazakhstan.
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10
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Conserved epitopes with high HLA-I population coverage are targets of CD8 + T cells associated with high IFN-γ responses against all dengue virus serotypes. Sci Rep 2020; 10:20497. [PMID: 33235334 PMCID: PMC7687909 DOI: 10.1038/s41598-020-77565-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Accepted: 11/03/2020] [Indexed: 12/15/2022] Open
Abstract
Cytotoxic CD8+ T cells are key for immune protection against viral infections. The breadth and cross-reactivity of these responses are important against rapidly mutating RNA viruses, such as dengue (DENV), yet how viral diversity affect T cell responses and their cross-reactivity against multiple variants of the virus remains poorly defined. In this study, an integrated analysis was performed to map experimentally validated CD8+ T cell epitopes onto the distribution of DENV genome sequences across the 4 serotypes worldwide. Despite the higher viral diversity observed within HLA-I restricted epitopes, mapping of 609 experimentally validated epitopes sequences on 3985 full-length viral genomes revealed 19 highly conserved epitopes across the four serotypes within the immunogenic regions of NS3, NS4B and NS5. These conserved epitopes were associated with a higher magnitude of IFN-γ response when compared to non-conserved epitopes and were restricted to 13 HLA class I genotypes, hence providing high coverage among human populations. Phylogeographic analyses showed that these epitopes are largely conserved in most of the endemic regions of the world, and with only some of these epitopes presenting distinct mutated variants circulating in South America and Asia.This study provides evidence for the existence of highly immunogenic and conserved epitopes across serotypes, which may impact design of new universal T-cell-inducing vaccine candidates that minimise detrimental effects of viral diversification and at the same time induce responses to a broad human population.
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11
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Sanchez-Velazquez R, de Lorenzo G, Tandavanitj R, Setthapramote C, Bredenbeek PJ, Bozzacco L, MacDonald MR, Clark JJ, Rice CM, Patel AH, Kohl A, Varjak M. Generation of a reporter yellow fever virus for high throughput antiviral assays. Antiviral Res 2020; 183:104939. [PMID: 32980446 PMCID: PMC7649875 DOI: 10.1016/j.antiviral.2020.104939] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 09/16/2020] [Accepted: 09/19/2020] [Indexed: 01/30/2023]
Abstract
Yellow fever virus (YFV), a member of the Flaviviridae family, is an arthropod-borne virus that can cause severe disease in humans with a lethality rate of up to 60%. Since 2017, increases in YFV activity in areas of South America and Africa have been described. Although a vaccine is available, named strain 17D (Theiler and Smith, 1937), it is contraindicated for use in the elderly, expectant mothers, immunocompromised people, among others. To this day there is no antiviral treatment against YFV to reduce the severity of viral infection. Here, we used a circular polymerase extension reaction (CPER)-based reverse genetics approach to generate a full-length reporter virus (YFVhb) by introducing a small HiBit tag in the NS1 protein. The reporter virus replicates at a similar rate to the parental YFV in HuH-7 cells. Using YFVhb, we designed a high throughput antiviral screening luciferase-based assay to identify inhibitors that target any step of the viral replication cycle. We validated our assay by using a range of inhibitors including drugs, immune sera and neutralizing single chain variable fragments (scFv). In light of the recent upsurge in YFV and a potential spread of the virus, this assay is a further tool in the development of antiviral therapy against YFV. Bacteria-free approach to rescue yellow fever virus. Novel tagged yellow fever virus that permits quantifiable assays. Usage of the novel tagged virus for screening of antivirals and immune sera. Novel antiviral compounds against YFV were identified.
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Affiliation(s)
| | | | | | | | - Peter J Bredenbeek
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY, USA
| | - Leonia Bozzacco
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY, USA
| | - Margaret R MacDonald
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY, USA
| | - Jordan J Clark
- MRC-University of Glasgow, Centre for Virus Research, Glasgow, UK
| | - Charles M Rice
- Laboratory of Virology and Infectious Disease, The Rockefeller University, New York, NY, USA
| | - Arvind H Patel
- MRC-University of Glasgow, Centre for Virus Research, Glasgow, UK
| | - Alain Kohl
- MRC-University of Glasgow, Centre for Virus Research, Glasgow, UK
| | - Margus Varjak
- MRC-University of Glasgow, Centre for Virus Research, Glasgow, UK.
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12
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Liang XY, Zhu QC, Liang JQ, Liu SY, Liu DX, Fung TS. Development of HiBiT-Tagged Recombinant Infectious Bronchitis Coronavirus for Efficient in vitro and in vivo Viral Quantification. Front Microbiol 2020; 11:2100. [PMID: 32983065 PMCID: PMC7485224 DOI: 10.3389/fmicb.2020.02100] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Accepted: 08/10/2020] [Indexed: 12/31/2022] Open
Abstract
Coronaviruses (CoVs) are enveloped (+) ssRNA viruses of veterinary and medical importance. Because recombinant CoVs with reporter proteins fused with viral proteins are usually non-viable or unstable, a small and quantifiable epitope tag would be beneficial to CoV research. In this study, we integrated the NanoLuc Binary Technology to the reverse genetics of infectious bronchitis virus (IBV), a prototypic gammacoronavirus. The 11-amino-acid HiBiT tag was inserted to the spike (S) or membrane (M) protein, and the recombinant IBVs (rS-HiBiT and rM-HiBiT) were characterized. Compared with the rIBV-p65 control, rS-HiBiT exhibited comparable growth kinetics, whereas rM-HiBiT replicated slightly slower. The levels of HiBiT-tagged S and M proteins in the infected cells or the culture supernatant could be both rapidly (~15 min) and efficiently (30 μL sample volume) determined using the HiBiT luminescence assay. Notably, replication of the HiBiT-tagged IBV could be monitored continuously in an infected chicken embryo, and rS-HiBiT was genetically stable for at least 20 passages. By integrating the HiBiT tagging system with CoV reverse genetics, this new reporter system may facilitate future study of CoV replication and pathogenesis.
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Affiliation(s)
- Xiao Ying Liang
- Guangdong Province Key Laboratory of Microbial Signals & Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Qing Chun Zhu
- Guangdong Province Key Laboratory of Microbial Signals & Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Jia Qi Liang
- Guangdong Province Key Laboratory of Microbial Signals & Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Si Ying Liu
- Guangdong Province Key Laboratory of Microbial Signals & Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
| | - Ding Xiang Liu
- Guangdong Province Key Laboratory of Microbial Signals & Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China.,Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou, China
| | - To Sing Fung
- Guangdong Province Key Laboratory of Microbial Signals & Disease Control, Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China.,Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou, China
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13
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Identification of Estrogen Receptor Modulators as Inhibitors of Flavivirus Infection. Antimicrob Agents Chemother 2020; 64:AAC.00289-20. [PMID: 32482672 DOI: 10.1128/aac.00289-20] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 05/26/2020] [Indexed: 02/06/2023] Open
Abstract
Flaviviruses such as Zika virus (ZIKV), dengue virus (DENV), and West Nile virus (WNV) are major global pathogens for which safe and effective antiviral therapies are not currently available. To identify antiviral small molecules with well-characterized safety and bioavailability profiles, we screened a library of 2,907 approved drugs and pharmacologically active compounds for inhibitors of ZIKV infection using a high-throughput cell-based immunofluorescence assay. Interestingly, estrogen receptor modulators raloxifene hydrochloride and quinestrol were among 15 compounds that significantly inhibited ZIKV infection in repeat screens. Subsequent validation studies revealed that these drugs effectively inhibit ZIKV, DENV, and WNV (Kunjin strain) infection at low micromolar concentrations with minimal cytotoxicity in Huh-7.5 hepatoma cells and HTR-8 placental trophoblast cells. Since these cells lack detectable expression of estrogen receptors-α and -β (ER-α and ER-β) and similar antiviral effects were observed in the context of subgenomic DENV and ZIKV replicons, these compounds appear to inhibit viral RNA replication in a manner that is independent of their known effects on estrogen receptor signaling. Taken together, quinestrol, raloxifene hydrochloride, and structurally related analogues warrant further investigation as potential therapeutics for treatment of flavivirus infections.
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14
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Genome-Wide Mutagenesis of Hepatitis C Virus Reveals Ability of Genome To Overcome Detrimental Mutations. J Virol 2020; 94:JVI.01327-19. [PMID: 31723027 DOI: 10.1128/jvi.01327-19] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 10/17/2019] [Indexed: 01/10/2023] Open
Abstract
To gain insight into the impact of mutations on the viability of the hepatitis C virus (HCV) genome, we created a set of full-genome mutant libraries, differing from the parent sequence as well as each other, by using a random mutagenesis approach; the proportion of mutations increased across these libraries with declining template amount or dATP concentration. The replication efficiencies of full-genome mutant libraries ranged between 71 and 329 focus-forming units (FFU) per 105 Huh7.5 cells. Mutant libraries with low proportions of mutations demonstrated low replication capabilities, whereas those with high proportions of mutations had their replication capabilities restored. Hepatoma cells transfected with selected mutant libraries, with low (4 mutations per 10,000 bp copied), moderate (33 mutations), and high (66 mutations) proportions of mutations, and their progeny were subjected to serial passage. Predominant virus variants (mutants) from these mutant libraries (Mutantl, Mutantm, and Mutanth, respectively) were evaluated for changes in growth kinetics and particle-to-FFU unit ratio, virus protein expression, and modulation of host cell protein synthesis. Mutantm and Mutantl variants produced >3.0-log-higher extracellular progeny per ml than the parent, and Mutanth produced progeny at a rate 1.0-log lower. More than 80% of the mutations were in a nonstructural part of the mutant genomes, the majority were nonsynonymous, and a moderate to large proportion were in the conserved regions. Our results suggest that the HCV genome has the ability to overcome lethal/deleterious mutations because of the high reproduction rate but highly selects for random, beneficial mutations.IMPORTANCE Hepatitis C virus (HCV) in vivo displays high genetic heterogeneity, which is partly due to the high reproduction and random substitutions during error-prone genome replication. It is difficult to introduce random substitutions in vitro because of limitations in inducing mutagenesis from the 5' end to the 3' end of the genome. Our study has overcome this limitation. We synthesized full-length genomes with few to several random mutations in the background of an HCV clone that can recapitulate all steps of the life cycle. Our study provides evidence of the capability of the HCV genome to overcome deleterious mutations and remain viable. Mutants that emerged from the libraries had diverse phenotype profiles compared to the parent, and putative adaptive mutations mapped to segments of the conserved nonstructural genome. We demonstrate the potential utility of our system for the study of sequence variation that ensures the survival and adaptation of HCV.
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15
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In Vivo Dynamics of Reporter Flaviviridae Viruses. J Virol 2019; 93:JVI.01191-19. [PMID: 31462560 DOI: 10.1128/jvi.01191-19] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 08/15/2019] [Indexed: 11/20/2022] Open
Abstract
Recombinant viruses possessing reporter proteins have been generated for virus research. In the case of the family Flaviviridae, we recently generated recombinant viruses, including the hepatitis C virus of the genus Hepacivirus, Japanese encephalitis virus (JEV) of the genus Flavivirus, and bovine viral diarrhea virus of the genus Pestivirus; all three viruses possess an 11-amino-acid subunit derived from NanoLuc luciferase (HiBiT). Here, we further developed the recombinant viruses and investigated their utility in vivo Recombinant viruses harboring HiBiT in the E, NS1, or NS3 protein constructed based on the predicted secondary structure, solvent-accessible surface area, and root mean square fluctuation of the proteins exhibited comparable replication to that of the wild-type virus in vitro The recombinant JEV carrying HiBiT in the NS1 protein exhibited propagation in mice comparable to that of the parental virus, and propagation of the recombinant was monitored by the luciferase activity. In addition, the recombinants of classical swine fever virus (CSFV) possessing HiBiT in the Erns or E2 protein also showed propagation comparable to that of the wild-type virus. The recombinant CSFV carrying HiBiT in Erns exhibited similar replication to the parental CSFV in pigs, and detection of viral propagation of this recombinant by luciferase activity was higher than that by quantitative PCR (qPCR). Taken together, these results demonstrated that the reporter Flaviviridae viruses generated herein are powerful tools for elucidating the viral life cycle and pathogeneses and provide a robust platform for the development of novel antivirals.IMPORTANCE In vivo applications of reporter viruses are necessary to understand viral pathogenesis and provide a robust platform for antiviral development. In developing such applications, determination of an ideal locus to accommodate foreign genes is important, because insertion of foreign genes into irrelevant loci can disrupt the protein functions required for viral replication. Here, we investigated the criteria to determine ideal insertion sites of foreign genes from the protein structure of viral proteins. The recombinant viruses generated by our criteria exhibited propagation comparable to that of parental viruses in vivo Our proteomic approach based on the flexibility profile of viral proteins may provide a useful tool for constructing reporter viruses, including Flaviviridae viruses.
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16
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Recombinant Hepatitis E Viruses Harboring Tags in the ORF1 Protein. J Virol 2019; 93:JVI.00459-19. [PMID: 31315997 PMCID: PMC6744232 DOI: 10.1128/jvi.00459-19] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2019] [Accepted: 07/09/2019] [Indexed: 12/15/2022] Open
Abstract
Hepatitis E virus (HEV) infection is an important cause of acute hepatitis and may lead to chronic infection in immunocompromised patients. Knowledge of the viral life cycle is incomplete due to the limited availability of functional tools. In particular, low levels of expression of the ORF1 protein or limited sensitivity of currently available antibodies or both limit our understanding of the viral replicase. Here, we report the successful establishment of subgenomic HEV replicons and full-length genomes harboring an epitope tag or a functional reporter in the ORF1 protein. These novel tools should allow further characterization of the HEV replication complex and to improve our understanding of the viral life cycle. Hepatitis E virus (HEV) is one of the most common causes of acute hepatitis and jaundice in the world. Current understanding of the molecular virology and pathogenesis of hepatitis E is incomplete, due particularly to the limited availability of functional tools. Here, we report the development of tagged HEV genomes as a novel tool to investigate the viral life cycle. A selectable subgenomic HEV replicon was subjected to random 15-nucleotide sequence insertion using transposon-based technology. Viable insertions in the open reading frame 1 (ORF1) protein were selected in a hepatoblastoma cell line. Functional insertion sites were identified downstream of the methyltransferase domain, in the hypervariable region (HVR), and between the helicase and RNA-dependent RNA polymerase domains. HEV genomes harboring a hemagglutinin (HA) epitope tag or a small luciferase (NanoLuc) in the HVR were found to be fully functional and to allow the production of infectious virus. NanoLuc allowed quantitative monitoring of HEV infection and replication by luciferase assay. The use of HA-tagged replicons and full-length genomes allowed localization of putative sites of HEV RNA replication by the simultaneous detection of viral RNA by fluorescence in situ hybridization and of ORF1 protein by immunofluorescence. Candidate HEV replication complexes were found in cytoplasmic dot-like structures which partially overlapped ORF2 and ORF3 proteins as well as exosomal markers. Hence, tagged HEV genomes yield new insights into the viral life cycle and should allow further investigation of the structure and composition of the viral replication complex. IMPORTANCE Hepatitis E virus (HEV) infection is an important cause of acute hepatitis and may lead to chronic infection in immunocompromised patients. Knowledge of the viral life cycle is incomplete due to the limited availability of functional tools. In particular, low levels of expression of the ORF1 protein or limited sensitivity of currently available antibodies or both limit our understanding of the viral replicase. Here, we report the successful establishment of subgenomic HEV replicons and full-length genomes harboring an epitope tag or a functional reporter in the ORF1 protein. These novel tools should allow further characterization of the HEV replication complex and to improve our understanding of the viral life cycle.
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17
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Płaszczyca A, Scaturro P, Neufeldt CJ, Cortese M, Cerikan B, Ferla S, Brancale A, Pichlmair A, Bartenschlager R. A novel interaction between dengue virus nonstructural protein 1 and the NS4A-2K-4B precursor is required for viral RNA replication but not for formation of the membranous replication organelle. PLoS Pathog 2019; 15:e1007736. [PMID: 31071189 PMCID: PMC6508626 DOI: 10.1371/journal.ppat.1007736] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 03/27/2019] [Indexed: 12/17/2022] Open
Abstract
Dengue virus (DENV) has emerged as major human pathogen. Despite the serious socio-economic impact of DENV-associated diseases, antiviral therapy is missing. DENV replicates in the cytoplasm of infected cells and induces a membranous replication organelle, formed by invaginations of the endoplasmic reticulum membrane and designated vesicle packets (VPs). Nonstructural protein 1 (NS1) of DENV is a multifunctional protein. It is secreted from cells to counteract antiviral immune responses, but also critically contributes to the severe clinical manifestations of dengue. In addition, NS1 is indispensable for viral RNA replication, but the underlying molecular mechanism remains elusive. In this study, we employed a combination of genetic, biochemical and imaging approaches to dissect the determinants in NS1 contributing to its various functions in the viral replication cycle. Several important observations were made. First, we identified a cluster of amino acid residues in the exposed region of the β-ladder domain of NS1 that are essential for NS1 secretion. Second, we revealed a novel interaction of NS1 with the NS4A-2K-4B cleavage intermediate, but not with mature NS4A or NS4B. This interaction is required for RNA replication, with two residues within the connector region of the NS1 “Wing” domain being crucial for binding of the NS4A-2K-4B precursor. By using a polyprotein expression system allowing the formation of VPs in the absence of viral RNA replication, we show that the NS1 –NS4A-2K-4B interaction is not required for VP formation, arguing that the association between these two proteins plays a more direct role in the RNA amplification process. Third, through analysis of polyproteins containing deletions in NS1, and employing a trans-complementation assay, we show that both cis and trans acting elements within NS1 contribute to VP formation, with the capability of NS1 mutants to form VPs correlating with their capability to support RNA replication. In conclusion, these results reveal a direct role of NS1 in VP formation that is independent from RNA replication, and argue for a critical function of a previously unrecognized NS4A-2K-NS4B precursor specifically interacting with NS1 and promoting viral RNA replication. Dengue virus (DENV) is one of the most prevalent mosquito-transmitted human pathogens. The only licensed vaccine has limited efficacy and an antiviral therapy is not available. The multifunctional non-structural protein 1 (NS1) of DENV is secreted from infected cells, counteracts antiviral immune response and contributes to the pathogenesis of DENV infection. In addition, NS1 is essential for the viral replication cycle but the underlying mechanism is unknown. Here we determined the viral interactome of NS1 and identified a novel interaction of NS1 with the NS4A-2K-4B cleavage intermediate, but not with NS4A and NS4B. This interaction is required for RNA replication. Additionally, we identified a domain in NS1 important for efficient secretion of this protein. Finally, we demonstrate that NS1 is required for the biogenesis of the membranous DENV replication organelle. This function does not require RNA replication and is independent from NS1 interaction with NS4A-2K-4B. Our results provide new insights into the role of NS1 in DENV RNA replication and establish a genetic map of residues in NS1 required for the diverse functions of this protein. These results should aid in the design of antiviral strategies targeting NS1, with the aim to suppress viral replication as well as severe disease manifestations.
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Affiliation(s)
- Anna Płaszczyca
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Pietro Scaturro
- Max-Planck Institute of Biochemistry, Innate Immunity Laboratory, Martinsried, Germany
- School of Medicine, Institute of Virology, Technical University of Munich, Munich, Germany
| | - Christopher John Neufeldt
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Mirko Cortese
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Berati Cerikan
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
| | - Salvatore Ferla
- School of Pharmacy & Pharmaceutical Sciences, Cardiff University, Cardiff, United Kingdom
| | - Andrea Brancale
- School of Pharmacy & Pharmaceutical Sciences, Cardiff University, Cardiff, United Kingdom
| | - Andreas Pichlmair
- Max-Planck Institute of Biochemistry, Innate Immunity Laboratory, Martinsried, Germany
- School of Medicine, Institute of Virology, Technical University of Munich, Munich, Germany
- German Center for Infection Research (DZIF), Munich Partner Site, Munich, Germany
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, University of Heidelberg, Heidelberg, Germany
- German Center for Infection Research (DZIF), Heidelberg Partner Site, Heidelberg, Germany
- * E-mail:
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18
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Zhang Q, Li N, Deng C, Zhang Z, Li X, Yoshii K, Ye H, Zhang B. Trans Complementation of Replication-defective Omsk Hemorrhagic Fever Virus for Antiviral Study. Virol Sin 2019; 34:412-422. [PMID: 30949960 DOI: 10.1007/s12250-019-00109-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Accepted: 02/28/2019] [Indexed: 12/25/2022] Open
Abstract
Omsk hemorrhagic fever virus (OHFV) is a tick-borne flavivirus classified as a biosafety level-4 (BSL4) pathogen. Studies of OHFV are restricted to be conducted within BSL4 laboratories. Currently, no commercial vaccines or antiviral drugs are available against OHFV infection. In this study, we recovered a replication-deficient OHFV with an NS1 deletion (OHFV-ΔNS1) and reporter virus replacing NS1 with the Gaussia luciferase (Gluc) (OHFV-ΔNS1-Gluc). Both the defective OHFV-ΔNS1 and OHFV-ΔNS1-Gluc virus could only replicate efficiently in the BHK21 cell line expressing NS1 (BHK21NS1) but not in naïve BHK21 cells. The Gluc reporter gene of OHFV-ΔNS1-Gluc virus was maintained stably after serial passaging of BHK21NS1 cells and was used to surrogate the replication of OHFV. Using NITD008, OHFV-ΔNS1-Gluc virus was validated for antiviral screening, and high-throughput screening parameters were optimized in a 96-well plate format with a calculated Z' value above 0.5. The OHFV-ΔNS1-Gluc reporter virus is a powerful tool for antiviral screening as well as viral replication and pathogenesis studies in BSL2 laboratories.
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Affiliation(s)
- Qiuyan Zhang
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Na Li
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Chenglin Deng
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China
| | - Zherui Zhang
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xiaodan Li
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China
| | - Kentaro Yoshii
- Laboratory of Public Health, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, 060-0818, Japan
| | - Hanqing Ye
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China
| | - Bo Zhang
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China.
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Perry JW, Tai AW. Random Insertional Mutagenesis of a Serotype 2 Dengue Virus Clone. Bio Protoc 2018; 8:e2975. [PMID: 30214914 DOI: 10.21769/bioprotoc.2975] [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: 11/02/2022] Open
Abstract
Protein tagging is a powerful method of investigating protein function. However, modifying positive-strand RNA virus proteins in the context of viral infection can be particularly difficult as their compact genomes and multifunctional proteins mean even small changes can inactivate or attenuate the virus. Although targeted approaches to functionally tag viral proteins have been successful, these approaches are time consuming and inefficient. A strategy that has been successfully applied to several RNA viruses is whole-genome transposon insertional mutagenesis. A library of viral genomes, each containing a single randomly placed small insertion, is selected by passaging in cell culture and the insertion sites can be identified using Next Generation Sequencing (NGS). Here we describe a protocol for transposon mutagenesis of the 16681 strain of dengue virus, serotype 2. Mutant dengue virus libraries containing short randomly placed insertions are passaged through mammalian cells and insertions are mapped by NGS of the viable progeny. The protocol is divided into four stages: transposon mutagenesis of a dengue cDNA clone, viral genome transfection into permissive cells, isolation of viral progeny genomes, and sequencing library preparation.
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Affiliation(s)
- Jeffrey W Perry
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Andrew W Tai
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, USA.,Department of Microbiology & Immunology, University of Michigan, Ann Arbor, MI, USA.,Medicine Service, Ann Arbor Veterans Administration Health System, Ann Arbor, MI, USA
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20
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Perry JW, Chen Y, Speliotes E, Tai AW. Functional Analysis of the Dengue Virus Genome Using an Insertional Mutagenesis Screen. J Virol 2018; 92:e02085-17. [PMID: 29321321 PMCID: PMC5972875 DOI: 10.1128/jvi.02085-17] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 01/03/2018] [Indexed: 12/29/2022] Open
Abstract
In the last few decades, dengue virus, an arbovirus, has spread to over 120 countries. Although a vaccine has been approved in some countries, limitations on its effectiveness and a lack of effective antiviral treatments reinforce the need for additional research. The functions of several viral nonstructural proteins are essentially unknown. To better understand the functions of these proteins and thus dengue virus pathogenesis, we embarked on a genomewide transposon mutagenesis screen with next-generation sequencing to determine sites in the viral genome that tolerate 15-nucleotide insertions. Using this approach, we generated support for several published predicted transmembrane and enzymatic domains. Next, we created 7 mutants containing the 15-nucleotide insertion from the original selection and found 6 of them were capable of replication in both mammalian and mosquito tissue culture cells. Interestingly, one mutation had a significant impairment of viral assembly, and this mutation may lead to a better understanding of viral assembly and release. In addition, we created a fully infectious virus expressing a functionally tagged NS4B protein, which will provide a much-needed tool to elucidate the role of NS4B in viral pathogenesis.IMPORTANCE Dengue virus is a mosquito-borne virus distributed in tropical and subtropical regions globally that can result in hospitalization and even death in some cases. Although a vaccine exists, its limitations and a lack of approved antiviral treatments highlight our limited understanding of dengue virus pathogenesis and host immunity. The functions of many viral proteins are poorly understood. We used a previously published approach using transposon mutagenesis to develop tools to study these proteins' functions by adding insertions randomly throughout the viral genomes. These genomes were transferred into cells, and infectious progeny were recovered to determine sites that tolerated insertions, as only the genomes that tolerated insertions would be able to propagate. Using these results, we created viruses with epitope tags, one in the viral structural protein Capsid and one in the viral nonstructural protein NS4B. Further investigation of these mutants may elucidate the roles of Capsid and NS4B during dengue virus infections.
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Affiliation(s)
- Jeffrey W Perry
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Yanhua Chen
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Elizabeth Speliotes
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Andrew W Tai
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, USA
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan, USA
- Medicine Service, Ann Arbor Veterans Administration Health System, Ann Arbor, Michigan, USA
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21
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Abstract
Reproduction of RNA viruses is typically error-prone due to the infidelity of their replicative machinery and the usual lack of proofreading mechanisms. The error rates may be close to those that kill the virus. Consequently, populations of RNA viruses are represented by heterogeneous sets of genomes with various levels of fitness. This is especially consequential when viruses encounter various bottlenecks and new infections are initiated by a single or few deviating genomes. Nevertheless, RNA viruses are able to maintain their identity by conservation of major functional elements. This conservatism stems from genetic robustness or mutational tolerance, which is largely due to the functional degeneracy of many protein and RNA elements as well as to negative selection. Another relevant mechanism is the capacity to restore fitness after genetic damages, also based on replicative infidelity. Conversely, error-prone replication is a major tool that ensures viral evolvability. The potential for changes in debilitated genomes is much higher in small populations, because in the absence of stronger competitors low-fit genomes have a choice of various trajectories to wander along fitness landscapes. Thus, low-fit populations are inherently unstable, and it may be said that to run ahead it is useful to stumble. In this report, focusing on picornaviruses and also considering data from other RNA viruses, we review the biological relevance and mechanisms of various alterations of viral RNA genomes as well as pathways and mechanisms of rehabilitation after loss of fitness. The relationships among mutational robustness, resilience, and evolvability of viral RNA genomes are discussed.
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22
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Characterization of Recombinant Flaviviridae Viruses Possessing a Small Reporter Tag. J Virol 2018; 92:JVI.01582-17. [PMID: 29093094 DOI: 10.1128/jvi.01582-17] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 10/19/2017] [Indexed: 01/13/2023] Open
Abstract
The family Flaviviridae consists of four genera, Flavivirus, Pestivirus, Pegivirus, and Hepacivirus, and comprises important pathogens of human and animals. Although the construction of recombinant viruses carrying reporter genes encoding fluorescent and bioluminescent proteins has been reported, the stable insertion of foreign genes into viral genomes retaining infectivity remains difficult. Here, we applied the 11-amino-acid subunit derived from NanoLuc luciferase to the engineering of the Flaviviridae viruses and then examined the biological characteristics of the viruses. We successfully generated recombinant viruses carrying the split-luciferase gene, including dengue virus, Japanese encephalitis virus, hepatitis C virus (HCV), and bovine viral diarrhea virus. The stability of the viruses was confirmed by five rounds of serial passages in the respective susceptible cell lines. The propagation of the recombinant luciferase viruses in each cell line was comparable to that of the parental viruses. By using a purified counterpart luciferase protein, this split-luciferase assay can be applicable in various cell lines, even when it is difficult to transduce the counterpart gene. The efficacy of antiviral reagents against the recombinant viruses could be monitored by the reduction of luciferase expression, which was correlated with that of viral RNA, and the recombinant HCV was also useful to examine viral dynamics in vivo Taken together, our findings indicate that the recombinant Flaviviridae viruses possessing the split NanoLuc luciferase gene generated here provide powerful tools to understand viral life cycle and pathogenesis and a robust platform to develop novel antivirals against Flaviviridae viruses.IMPORTANCE The construction of reporter viruses possessing a stable transgene capable of expressing specific signals is crucial to investigations of viral life cycle and pathogenesis and the development of antivirals. However, it is difficult to maintain the stability of a large foreign gene, such as those for fluorescence and bioluminescence, after insertion into a viral genome. Here, we successfully generated recombinant Flaviviridae viruses carrying the 11-amino-acid subunit derived from NanoLuc luciferase and demonstrated that these viruses are applicable to in vitro and in vivo experiments, suggesting that these recombinant Flaviviridae viruses are powerful tools for increasing our understanding of viral life cycle and pathogenesis and that these recombinant viruses will provide a robust platform to develop antivirals against Flaviviridae viruses.
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