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Kotaki T, Kanai Y, Onishi M, Minami S, Chen Z, Nouda R, Nurdin JA, Yamasaki M, Kobayashi T. Generation of single-round infectious rotavirus with a mutation in the intermediate capsid protein VP6. J Virol 2024; 98:e0076224. [PMID: 38837379 PMCID: PMC11265344 DOI: 10.1128/jvi.00762-24] [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: 05/02/2024] [Accepted: 05/02/2024] [Indexed: 06/07/2024] Open
Abstract
Rotavirus causes severe diarrhea in infants. Although live attenuated rotavirus vaccines are available, vaccine-derived infections have been reported, which warrants development of next-generation rotavirus vaccines. A single-round infectious virus is a promising vaccine platform; however, this platform has not been studied extensively in the context of rotavirus. Here, we aimed to develop a single-round infectious rotavirus by impairing the function of the viral intermediate capsid protein VP6. Recombinant rotaviruses harboring mutations in VP6 were rescued using a reverse genetics system. Mutations were targeted at VP6 residues involved in virion assembly. Although the VP6-mutated rotavirus expressed viral proteins, it did not produce progeny virions in wild-type cells; however, the virus did produce progeny virions in VP6-expressing cells. This indicates that the VP6-mutated rotavirus is a single-round infectious rotavirus. Insertion of a foreign gene, and replacement of the VP7 gene segment with that of human rotavirus clinical isolates, was successful. No infectious virions were detected in mice infected with the single-round infectious rotavirus. Immunizing mice with the single-round infectious rotavirus induced neutralizing antibody titers as high as those induced by wild-type rotavirus. Taken together, the data suggest that this single-round infectious rotavirus has potential as a safe and effective rotavirus vaccine. This system is also applicable for generation of safe and orally administrable viral vectors.IMPORTANCERotavirus, a leading cause of acute gastroenteritis in infants, causes an annual estimated 128,500 infant deaths worldwide. Although live attenuated rotavirus vaccines are available, they are replicable and may cause vaccine-derived infections. Thus, development of safe and effective rotavirus vaccine is important. In this study, we report the development of a single-round infectious rotavirus that can replicate only in cells expressing viral VP6 protein. We demonstrated that (1) the single-round infectious rotavirus did not replicate in wild-type cells or in mice; (2) insertion of foreign genes and replacement of the outer capsid gene were possible; and (3) it was as immunogenic as the wild-type virus. Thus, the mutated virus shows promise as a next-generation rotavirus vaccine. The system is also applicable to orally administrable viral vectors, facilitating development of vaccines against other enteric pathogens.
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Affiliation(s)
- Tomohiro Kotaki
- Department of Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Yuta Kanai
- Department of Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Megumi Onishi
- Department of Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Shohei Minami
- Department of Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Zelin Chen
- Department of Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Ryotaro Nouda
- Department of Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Jeffery A. Nurdin
- Department of Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Moeko Yamasaki
- Department of Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Takeshi Kobayashi
- Department of Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
- Center for Infectious Disease Education and Research, Osaka University, Osaka, Japan
- Center for Advanced Modalities and DDS, Osaka University, Osaka, Japan
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2
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Vetter J, Papa G, Tobler K, Rodriguez JM, Kley M, Myers M, Wiesendanger M, Schraner EM, Luque D, Burrone OR, Fraefel C, Eichwald C. The recruitment of TRiC chaperonin in rotavirus viroplasms correlates with virus replication. mBio 2024; 15:e0049924. [PMID: 38470055 PMCID: PMC11005421 DOI: 10.1128/mbio.00499-24] [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: 02/19/2024] [Accepted: 02/22/2024] [Indexed: 03/13/2024] Open
Abstract
Rotavirus (RV) replication takes place in the viroplasms, cytosolic inclusions that allow the synthesis of virus genome segments and their encapsidation in the core shell, followed by the addition of the second layer of the virion. The viroplasms are composed of several viral proteins, including NSP5, which serves as the main building block. Microtubules, lipid droplets, and miRNA-7 are among the host components recruited in viroplasms. We investigated the interaction between RV proteins and host components of the viroplasms by performing a pull-down assay of lysates from RV-infected cells expressing NSP5-BiolD2. Subsequent tandem mass spectrometry identified all eight subunits of the tailless complex polypeptide I ring complex (TRiC), a cellular chaperonin responsible for folding at least 10% of the cytosolic proteins. Our confirmed findings reveal that TRiC is brought into viroplasms and wraps around newly formed double-layered particles. Chemical inhibition of TRiC and silencing of its subunits drastically reduced virus progeny production. Through direct RNA sequencing, we show that TRiC is critical for RV replication by controlling dsRNA genome segment synthesis, particularly negative-sense single-stranded RNA. Importantly, cryo-electron microscopy analysis shows that TRiC inhibition results in defective virus particles lacking genome segments and polymerase complex (VP1/VP3). Moreover, TRiC associates with VP2 and NSP5 but not with VP1. Also, VP2 is shown to be essential for recruiting TRiC in viroplasms and preserving their globular morphology. This study highlights the essential role of TRiC in viroplasm formation and in facilitating virion assembly during the RV life cycle. IMPORTANCE The replication of rotavirus takes place in cytosolic inclusions termed viroplasms. In these inclusions, the distinct 11 double-stranded RNA genome segments are co-packaged to complete a genome in newly generated virus particles. In this study, we show for the first time that the tailless complex polypeptide I ring complex (TRiC), a cellular chaperonin responsible for the folding of at least 10% of the cytosolic proteins, is a component of viroplasms and is required for the synthesis of the viral negative-sense single-stranded RNA. Specifically, TRiC associates with NSP5 and VP2, the cofactor involved in RNA replication. Our study adds a new component to the current model of rotavirus replication, where TRiC is recruited to viroplasms to assist replication.
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Affiliation(s)
- Janine Vetter
- Institute of Virology, University of Zurich, Zurich, Switzerland
| | - Guido Papa
- Molecular Immunology Lab, International Centre for Genetic Engineering and Biotechnology, Trieste, Italy
| | - Kurt Tobler
- Institute of Virology, University of Zurich, Zurich, Switzerland
| | - Javier M. Rodriguez
- Department of Structure of Macromolecules, Centro Nacional de Biotecnología/CSIC, Cantoblanco, Madrid, Spain
| | - Manuel Kley
- Institute of Virology, University of Zurich, Zurich, Switzerland
| | - Michael Myers
- Proteomics Lab, International Centre for Genetic Engineering and Biotechnology, Trieste, Italy
| | - Mahesa Wiesendanger
- Institute of Virology, University of Zurich, Zurich, Switzerland
- Institute of Veterinary Anatomy, University of Zurich, Zurich, Switzerland
| | - Elisabeth M. Schraner
- Institute of Virology, University of Zurich, Zurich, Switzerland
- Institute of Veterinary Anatomy, University of Zurich, Zurich, Switzerland
| | - Daniel Luque
- School of Biomedical Sciences, The University of New South Wales, Sydney, New South Wales, Australia
- Electron Microscope Unit, Mark Wainwright Analytical Centre, The University of New South Wales, Sydney, New South Wales, Australia
| | - Oscar R. Burrone
- Molecular Immunology Lab, International Centre for Genetic Engineering and Biotechnology, Trieste, Italy
| | - Cornel Fraefel
- Institute of Virology, University of Zurich, Zurich, Switzerland
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Anderson ML, Sullivan OM, Nichols SL, Kaylor L, Kelly DF, McDonald Esstman S. Rotavirus core shell protein sites that regulate intra-particle polymerase activity. J Virol 2023; 97:e0086023. [PMID: 37830817 PMCID: PMC10617381 DOI: 10.1128/jvi.00860-23] [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: 06/06/2023] [Accepted: 09/06/2023] [Indexed: 10/14/2023] Open
Abstract
IMPORTANCE Rotaviruses are important causes of severe gastroenteritis in young children. A characteristic feature of rotaviruses is that they copy ribonucleic acid (RNA) inside of the viral particle. In fact, the viral polymerase (VP1) only functions when it is connected to the viral inner core shell protein (VP2). Here, we employed a biochemical assay to identify which sites of VP2 are critical for regulating VP1 activity. Specifically, we engineered VP2 proteins to contain amino acid changes at structurally defined sites and assayed them for their capacity to support VP1 function in a test tube. Through this work, we were able to identify several VP2 residues that appeared to regulate the activity of the polymerase, positively and negatively. These results are important because they help explain how rotavirus synthesizes its RNA while inside of particles and they identify targets for the future rational design of drugs to prevent rotavirus disease.
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Affiliation(s)
| | - Owen M. Sullivan
- Department of Biology, Wake Forest University, Winston-Salem, North Carolina, USA
| | - Sarah L. Nichols
- Department of Biology, Wake Forest University, Winston-Salem, North Carolina, USA
| | - Liam Kaylor
- Department of Biomedical Engineering, State University, University Park, Pennsylvania, USA
| | - Deborah F. Kelly
- Department of Biomedical Engineering, State University, University Park, Pennsylvania, USA
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Asensio-Cob D, Rodríguez JM, Luque D. Rotavirus Particle Disassembly and Assembly In Vivo and In Vitro. Viruses 2023; 15:1750. [PMID: 37632092 PMCID: PMC10458742 DOI: 10.3390/v15081750] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 08/11/2023] [Accepted: 08/14/2023] [Indexed: 08/27/2023] Open
Abstract
Rotaviruses (RVs) are non-enveloped multilayered dsRNA viruses that are major etiologic agents of diarrheal disease in humans and in the young in a large number of animal species. The viral particle is composed of three different protein layers that enclose the segmented dsRNA genome and the transcriptional complexes. Each layer defines a unique subparticle that is associated with a different phase of the replication cycle. Thus, while single- and double-layered particles are associated with the intracellular processes of selective packaging, genome replication, and transcription, the viral machinery necessary for entry is located in the third layer. This modular nature of its particle allows rotaviruses to control its replication cycle by the disassembly and assembly of its structural proteins. In this review, we examine the significant advances in structural, molecular, and cellular RV biology that have contributed during the last few years to illuminating the intricate details of the RV particle disassembly and assembly processes.
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Affiliation(s)
- Dunia Asensio-Cob
- Department of Molecular Medicine, Peter Gilgan Centre for Research and Learning, The Hospital for Sick Children, 686 Bay Street, Toronto, ON M5G0A4, Canada;
| | - Javier M. Rodríguez
- Department of Structure of Macromolecules, Centro Nacional de Biotecnología/CSIC, Cantoblanco, 28049 Madrid, Spain
| | - Daniel Luque
- Electron Microscopy Unit UCCT/ISCIII, 28220 Majadahonda, Spain
- School of Biomedical Sciences, The University of New South Wales, Sydney, NSW 2052, Australia
- Electron Microscope Unit, Mark Wainwright Analytical Centre, The University of New South Wales, Sydney, NSW 2052, Australia
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Flexibility of the Rotavirus NSP2 C-Terminal Region Supports Factory Formation via Liquid-Liquid Phase Separation. J Virol 2023; 97:e0003923. [PMID: 36749077 PMCID: PMC9973012 DOI: 10.1128/jvi.00039-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Many viruses sequester the materials needed for their replication into discrete subcellular factories. For rotaviruses (RVs), these factories are called viroplasms, and they are formed in the host cell cytosol via the process of liquid-liquid phase separation (LLPS). The nonstructural protein 2 (NSP2) and its binding partner, nonstructural protein 5 (NSP5), are critical for viroplasm biogenesis. Yet it is not fully understood how NSP2 and NSP5 cooperate to form factories. The C-terminal region (CTR) of NSP2 (residues 291 to 317) is flexible, allowing it to participate in domain-swapping interactions that promote interoctamer interactions and, presumably, viroplasm formation. Molecular dynamics simulations showed that a lysine-to-glutamic acid change at position 294 (K294E) reduces NSP2 CTR flexibility in silico. To test the impact of reduced NSP2 CTR flexibility during infection, we engineered a mutant RV bearing this change (rRV-NSP2K294E). Single-cycle growth assays revealed a >1.2-log reduction in endpoint titers for rRV-NSP2K294E versus the wild-type control (rRV-WT). Using immunofluorescence assays, we found that rRV-NSP2K294E formed smaller, more numerous viroplasms than rRV-WT. Live-cell imaging experiments confirmed these results and revealed that rRV-NSP2K294E factories had delayed fusion kinetics. Moreover, NSP2K294E and several other CTR mutants formed fewer viroplasm-like structures in NSP5 coexpressing cells than did control NSP2WT. Finally, NSP2K294E exhibited defects in its capacity to induce LLPS droplet formation in vitro when incubated alongside NSP5. These results underscore the importance of NSP2 CTR flexibility in supporting the biogenesis of RV factories. IMPORTANCE Viruses often condense the materials needed for their replication into discrete intracellular factories. For rotaviruses, agents of severe gastroenteritis in children, factory formation is mediated in part by an octameric protein called NSP2. A flexible C-terminal region of NSP2 has been proposed to link several NSP2 octamers together, a feature that might be important for factory formation. Here, we created a change in NSP2 that reduced C-terminal flexibility and analyzed the impact on rotavirus factories. We found that the change caused the formation of smaller and more numerous factories that could not readily fuse together like those of the wild-type virus. The altered NSP2 protein also had a reduced capacity to form factory-like condensates in a test tube. Together, these results add to our growing understanding of how NSP2 supports rotavirus factory formation-a key step of viral replication.
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Kawagishi T, Sánchez-Tacuba L, Feng N, Costantini VP, Tan M, Jiang X, Green KY, Vinjé J, Ding S, Greenberg HB. Mucosal and systemic neutralizing antibodies to norovirus induced in infant mice orally inoculated with recombinant rotaviruses. Proc Natl Acad Sci U S A 2023; 120:e2214421120. [PMID: 36821582 PMCID: PMC9992845 DOI: 10.1073/pnas.2214421120] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2022] [Accepted: 01/26/2023] [Indexed: 02/24/2023] Open
Abstract
Rotaviruses (RVs) preferentially replicate in the small intestine and frequently cause severe diarrheal disease, and the following enteric infection generally induces variable levels of protective systemic and mucosal immune responses in humans and other animals. Rhesus rotavirus (RRV) is a simian RV that was previously used as a human RV vaccine and has been extensively studied in mice. Although RRV replicates poorly in the suckling mouse intestine, infection induces a robust and protective antibody response. The recent availability of plasmid only-based RV reverse genetics systems has enabled the generation of recombinant RVs expressing foreign proteins. However, recombinant RVs have not yet been experimentally tested as potential vaccine vectors to immunize against other gastrointestinal pathogens in vivo. This is a newly available opportunity because several live-attenuated RV vaccines are already widely administered to infants and young children worldwide. To explore the feasibility of using RV as a dual vaccine vector, we rescued replication-competent recombinant RRVs harboring bicistronic gene segment 7 that encodes the native RV nonstructural protein 3 (NSP3) protein and a human norovirus (HuNoV) VP1 protein or P domain from the predominant genotype GII.4. The rescued viruses expressed HuNoV VP1 or P protein in infected cells in vitro and elicited systemic and local antibody responses to HuNoV and RRV following oral infection of suckling mice. Serum IgG and fecal IgA from infected suckling mice bound to and neutralized both RRV and HuNoV. These findings have encouraging practical implications for the design of RV-based next-generation multivalent enteric vaccines to target HuNoV and other human enteric pathogens.
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Affiliation(s)
- Takahiro Kawagishi
- Division of Gastroenterology and Hepatology, Department of Medicine, Stanford University School of Medicine, Stanford, CA94305
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA94305
- Department of Veterans Affairs, VA Palo Alto Health Care System, Palo Alto, CA94304
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO63110
| | - Liliana Sánchez-Tacuba
- Division of Gastroenterology and Hepatology, Department of Medicine, Stanford University School of Medicine, Stanford, CA94305
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA94305
- Department of Veterans Affairs, VA Palo Alto Health Care System, Palo Alto, CA94304
| | - Ningguo Feng
- Division of Gastroenterology and Hepatology, Department of Medicine, Stanford University School of Medicine, Stanford, CA94305
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA94305
- Department of Veterans Affairs, VA Palo Alto Health Care System, Palo Alto, CA94304
| | - Veronica P. Costantini
- National Calicivirus Laboratory, Centers for Disease Control and Prevention, Atlanta, GA30333
| | - Ming Tan
- Divison of Infectious Diseases, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH45229
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH45229
| | - Xi Jiang
- Divison of Infectious Diseases, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH45229
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH45229
| | - Kim Y. Green
- Laboratory of Infectious Disease, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD20892
| | - Jan Vinjé
- National Calicivirus Laboratory, Centers for Disease Control and Prevention, Atlanta, GA30333
| | - Siyuan Ding
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO63110
| | - Harry B. Greenberg
- Division of Gastroenterology and Hepatology, Department of Medicine, Stanford University School of Medicine, Stanford, CA94305
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA94305
- Department of Veterans Affairs, VA Palo Alto Health Care System, Palo Alto, CA94304
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7
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Strauss S, Acker J, Papa G, Desirò D, Schueder F, Borodavka A, Jungmann R. Principles of RNA recruitment to viral ribonucleoprotein condensates in a segmented dsRNA virus. eLife 2023; 12:e68670. [PMID: 36700549 PMCID: PMC9925054 DOI: 10.7554/elife.68670] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 01/26/2023] [Indexed: 01/27/2023] Open
Abstract
Rotaviruses transcribe 11 distinct RNAs that must be co-packaged prior to their replication to make an infectious virion. During infection, nontranslating rotavirus transcripts accumulate in cytoplasmic protein-RNA granules known as viroplasms that support segmented genome assembly and replication via a poorly understood mechanism. Here, we analysed the RV transcriptome by combining DNA-barcoded smFISH of rotavirus-infected cells. Rotavirus RNA stoichiometry in viroplasms appears to be distinct from the cytoplasmic transcript distribution, with the largest transcript being the most enriched in viroplasms, suggesting a selective RNA enrichment mechanism. While all 11 types of transcripts accumulate in viroplasms, their stoichiometry significantly varied between individual viroplasms. Accumulation of transcripts requires the presence of 3' untranslated terminal regions and viroplasmic localisation of the viral polymerase VP1, consistent with the observed lack of polyadenylated transcripts in viroplasms. Our observations reveal similarities between viroplasms and other cytoplasmic RNP granules and identify viroplasmic proteins as drivers of viral RNA assembly during viroplasm formation.
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Affiliation(s)
| | - Julia Acker
- Department of Biochemistry, University of CambridgeCambridgeUnited Kingdom
| | - Guido Papa
- Molecular Immunology Laboratory, International Centre for Genetic Engineering and BiotechnologyTriesteItaly
| | - Daniel Desirò
- Department of Biochemistry, University of CambridgeCambridgeUnited Kingdom
| | - Florian Schueder
- Max Planck Institute of BiochemistryMunichGermany
- Department of Physics and Center for Nanoscience, Ludwig Maximilian UniversityMunichGermany
| | | | - Ralf Jungmann
- Max Planck Institute of BiochemistryMunichGermany
- Department of Physics and Center for Nanoscience, Ludwig Maximilian UniversityMunichGermany
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Rotavirus Spike Protein VP4 Mediates Viroplasm Assembly by Association to Actin Filaments. J Virol 2022; 96:e0107422. [PMID: 35938869 PMCID: PMC9472636 DOI: 10.1128/jvi.01074-22] [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] [Indexed: 11/30/2022] Open
Abstract
Rotavirus (RV) viroplasms are cytosolic inclusions where both virus genome replication and primary steps of virus progeny assembly take place. A stabilized microtubule cytoskeleton and lipid droplets are required for the viroplasm formation, which involves several virus proteins. The viral spike protein VP4 has not previously been shown to have a direct role in viroplasm formation. However, it is involved with virus-cell attachment, endocytic internalization, and virion morphogenesis. Moreover, VP4 interacts with actin cytoskeleton components, mainly in processes involving virus entrance and egress, and thereby may have an indirect role in viroplasm formation. In this study, we used reverse genetics to construct a recombinant RV, rRV/VP4-BAP, that contains a biotin acceptor peptide (BAP) in the K145-G150 loop of the VP4 lectin domain, permitting live monitoring. The recombinant virus was replication competent but showed a reduced fitness. We demonstrate that rRV/VP4-BAP infection, as opposed to rRV/wt infection, did not lead to a reorganized actin cytoskeleton as viroplasms formed were insensitive to drugs that depolymerize actin and inhibit myosin. Moreover, wild-type (wt) VP4, but not VP4-BAP, appeared to associate with actin filaments. Similarly, VP4 in coexpression with NSP5 and NSP2 induced a significant increase in the number of viroplasm-like structures. Interestingly, a small peptide mimicking loop K145-G150 rescued the phenotype of rRV/VP4-BAP by increasing its ability to form viroplasms and hence improve virus progeny formation. Collectively, these results provide a direct link between VP4 and the actin cytoskeleton to catalyze viroplasm assembly. IMPORTANCE The spike protein VP4 participates in diverse steps of the rotavirus (RV) life cycle, including virus-cell attachment, internalization, modulation of endocytosis, virion morphogenesis, and virus egress. Using reverse genetics, we constructed for the first time a recombinant RV, rRV/VP4-BAP, harboring a heterologous peptide in the lectin domain (loop K145-G150) of VP4. The rRV/VP4-BAP was replication competent but with reduced fitness due to a defect in the ability to reorganize the actin cytoskeleton, which affected the efficiency of viroplasm assembly. This defect was rescued by adding a permeable small-peptide mimicking the wild-type VP4 loop K145-G150. In addition to revealing a new role of VP4, our findings suggest that rRV harboring an engineered VP4 could be used as a new dual vaccination platform providing immunity against RV and additional heterologous antigens.
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Han F, Zhang Y, Xu A, Wang X, He Y, Song N, Gao T. Genome-wide identification and characterization of Toll-like receptor genes in black rockfish (Sebastes schlegelii) and their response mechanisms following poly (I:C) injection. Comp Biochem Physiol C Toxicol Pharmacol 2022; 254:109277. [PMID: 35085815 DOI: 10.1016/j.cbpc.2022.109277] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 01/10/2022] [Accepted: 01/19/2022] [Indexed: 12/13/2022]
Abstract
Toll-like receptors (TLRs) are canonical transmembrane receptors that play an important role in defending against invading pathogens. In this study, we identified a total of 12 TLR genes in black rockfish (Sebastes schlegelii) with an analysis of their sequence characterizations. The phylogenetic analysis suggested that 12 distinct TLRs were grouped into five subfamilies (i.e., TLR1, TLR3, TLR5, TLR7, and TLR11 subfamilies), and each SsTLR gene respectively corresponded to the orthologs genes of other species. The protein domain analysis indicated that TLRs are type I transmembrane proteins, including an extracellular leucine-rich repeat (LRR), a transmembrane region (TM) domain and an intracellular Toll/IL-1 receptor (TIR) domain. The evolutionary ratios indicted that 12 SsTLRs were under purifying selection. qRT-PCR assays exhibited diverse TLRs molecular expression patterns in the heart, brain, head kidney, kidney, liver, intestine, and spleen of 3 black rockfish, and the expression levels were high in some immune tissues (e.g., head kidney, kidney, and spleen). Subsequently, 30 fish were equally divided into 2 groups i.e., poly (I:C)-treated and PBS-Control groups. After poly (I:C) injection, eight SsTLRs, i.e., SsTLR2, SsTLR2-1, SsTLR2-2, SsTLR3, SsTLR5S, SsTLR7, SsTLR8 and SsTLR22, were dramatically increased. Altogether these results contribute to understanding how SsTLRs respond to immune defense after poly (I:C) injection and provide researchers with comprehensive TLR gene family data of black rockfish.
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Affiliation(s)
- Fei Han
- Fisheries College, Ocean University of China, Qingdao, Shandong 266003, China
| | - Yuan Zhang
- Fisheries College, Ocean University of China, Qingdao, Shandong 266003, China
| | - Anle Xu
- Fishery College, Zhejiang Ocean University, Zhoushan, Zhejiang 316022, China
| | - Xiaoyan Wang
- Fishery College, Zhejiang Ocean University, Zhoushan, Zhejiang 316022, China
| | - Yan He
- College of Marine Life Sciences, Ocean University of China, Qingdao, Shandong 266003, China
| | - Na Song
- Fisheries College, Ocean University of China, Qingdao, Shandong 266003, China
| | - Tianxiang Gao
- Fishery College, Zhejiang Ocean University, Zhoushan, Zhejiang 316022, China.
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10
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Geiger F, Acker J, Papa G, Wang X, Arter WE, Saar KL, Erkamp NA, Qi R, Bravo JPK, Strauss S, Krainer G, Burrone OR, Jungmann R, Knowles TPJ, Engelke H, Borodavka A. Liquid-liquid phase separation underpins the formation of replication factories in rotaviruses. EMBO J 2021; 40:e107711. [PMID: 34524703 PMCID: PMC8561643 DOI: 10.15252/embj.2021107711] [Citation(s) in RCA: 51] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 08/23/2021] [Accepted: 08/27/2021] [Indexed: 12/29/2022] Open
Abstract
RNA viruses induce the formation of subcellular organelles that provide microenvironments conducive to their replication. Here we show that replication factories of rotaviruses represent protein-RNA condensates that are formed via liquid-liquid phase separation of the viroplasm-forming proteins NSP5 and rotavirus RNA chaperone NSP2. Upon mixing, these proteins readily form condensates at physiologically relevant low micromolar concentrations achieved in the cytoplasm of virus-infected cells. Early infection stage condensates could be reversibly dissolved by 1,6-hexanediol, as well as propylene glycol that released rotavirus transcripts from these condensates. During the early stages of infection, propylene glycol treatments reduced viral replication and phosphorylation of the condensate-forming protein NSP5. During late infection, these condensates exhibited altered material properties and became resistant to propylene glycol, coinciding with hyperphosphorylation of NSP5. Some aspects of the assembly of cytoplasmic rotavirus replication factories mirror the formation of other ribonucleoprotein granules. Such viral RNA-rich condensates that support replication of multi-segmented genomes represent an attractive target for developing novel therapeutic approaches.
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Affiliation(s)
- Florian Geiger
- Department of ChemistryLudwig‐Maximilians‐Universität MünchenMunichGermany
| | - Julia Acker
- Department of BiochemistryUniversity of CambridgeCambridgeUK
| | - Guido Papa
- International Center for Genetic Engineering and BiotechnologyTriesteItaly
- Present address:
Medical Research Council Laboratory of Molecular Biology (MRC LMB)CambridgeUK
| | - Xinyu Wang
- Department of BiochemistryUniversity of CambridgeCambridgeUK
| | | | - Kadi L Saar
- Department of ChemistryUniversity of CambridgeCambridgeUK
| | - Nadia A Erkamp
- Department of ChemistryUniversity of CambridgeCambridgeUK
| | - Runzhang Qi
- Department of ChemistryUniversity of CambridgeCambridgeUK
| | - Jack PK Bravo
- Department of BiochemistryUniversity of CambridgeCambridgeUK
- Present address:
Department of Molecular BiosciencesUniversity of Texas at AustinAustinTXUSA
| | - Sebastian Strauss
- Department of Physics and Center for NanoscienceMax Planck Institute of BiochemistryMunichGermany
| | - Georg Krainer
- Department of ChemistryUniversity of CambridgeCambridgeUK
| | - Oscar R Burrone
- International Center for Genetic Engineering and BiotechnologyTriesteItaly
| | - Ralf Jungmann
- Department of Physics and Center for NanoscienceMax Planck Institute of BiochemistryMunichGermany
| | | | - Hanna Engelke
- Department of ChemistryLudwig‐Maximilians‐Universität MünchenMunichGermany
- Institute of Pharmaceutical SciencesKarl‐Franzens‐Universität GrazGrazAustria
| | - Alexander Borodavka
- Department of ChemistryLudwig‐Maximilians‐Universität MünchenMunichGermany
- Department of BiochemistryUniversity of CambridgeCambridgeUK
- Department of Physics and Center for NanoscienceMax Planck Institute of BiochemistryMunichGermany
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11
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Caddy S, Papa G, Borodavka A, Desselberger U. Rotavirus research: 2014-2020. Virus Res 2021; 304:198499. [PMID: 34224769 DOI: 10.1016/j.virusres.2021.198499] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 06/24/2021] [Accepted: 06/25/2021] [Indexed: 02/09/2023]
Abstract
Rotaviruses are major causes of acute gastroenteritis in infants and young children worldwide and also cause disease in the young of many other mammalian and of avian species. During the recent 5-6 years rotavirus research has benefitted in a major way from the establishment of plasmid only-based reverse genetics systems, the creation of human and other mammalian intestinal enteroids, and from the wide application of structural biology (cryo-electron microscopy, cryo-EM tomography) and complementary biophysical approaches. All of these have permitted to gain new insights into structure-function relationships of rotaviruses and their interactions with the host. This review follows different stages of the viral replication cycle and summarizes highlights of structure-function studies of rotavirus-encoded proteins (both structural and non-structural), molecular mechanisms of viral replication including involvement of cellular proteins and lipids, the spectrum of viral genomic and antigenic diversity, progress in understanding of innate and acquired immune responses, and further developments of prevention of rotavirus-associated disease.
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Affiliation(s)
- Sarah Caddy
- Cambridge Institute for Therapeutic Immunology and Infectious Disease Jeffery Cheah Biomedical Centre, Cambridge, CB2 0AW, UK.
| | - Guido Papa
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus Francis Crick Avenue, Cambridge, CB2 0QH, UK.
| | - Alexander Borodavka
- Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, UK.
| | - Ulrich Desselberger
- Department of Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK.
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12
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Bravo JPK, Bartnik K, Venditti L, Acker J, Gail EH, Colyer A, Davidovich C, Lamb DC, Tuma R, Calabrese AN, Borodavka A. Structural basis of rotavirus RNA chaperone displacement and RNA annealing. Proc Natl Acad Sci U S A 2021; 118:e2100198118. [PMID: 34615715 PMCID: PMC8521686 DOI: 10.1073/pnas.2100198118] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/12/2021] [Indexed: 01/13/2023] Open
Abstract
Rotavirus genomes are distributed between 11 distinct RNA molecules, all of which must be selectively copackaged during virus assembly. This likely occurs through sequence-specific RNA interactions facilitated by the RNA chaperone NSP2. Here, we report that NSP2 autoregulates its chaperone activity through its C-terminal region (CTR) that promotes RNA-RNA interactions by limiting its helix-unwinding activity. Unexpectedly, structural proteomics data revealed that the CTR does not directly interact with RNA, while accelerating RNA release from NSP2. Cryo-electron microscopy reconstructions of an NSP2-RNA complex reveal a highly conserved acidic patch on the CTR, which is poised toward the bound RNA. Virus replication was abrogated by charge-disrupting mutations within the acidic patch but completely restored by charge-preserving mutations. Mechanistic similarities between NSP2 and the unrelated bacterial RNA chaperone Hfq suggest that accelerating RNA dissociation while promoting intermolecular RNA interactions may be a widespread strategy of RNA chaperone recycling.
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Affiliation(s)
- Jack P K Bravo
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, LS2 9JT Leeds, United Kingdom
| | - Kira Bartnik
- Department of Chemistry, Center for NanoScience, Nanosystems Initiative Munich, Centre for Integrated Protein Science Munich, Ludwig Maximilian University of Munich, D-81377 Munich, Germany
| | - Luca Venditti
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom
| | - Julia Acker
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom
| | - Emma H Gail
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, VIC 3800, Australia
- Australian Research Council (ARC) Centre of Excellence in Advanced Molecular Imaging, European Molecular Biology Laboratory (EMBL) Australia, Clayton, VIC 3800, Australia
| | - Alice Colyer
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, LS2 9JT Leeds, United Kingdom
| | - Chen Davidovich
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton, VIC 3800, Australia
- Australian Research Council (ARC) Centre of Excellence in Advanced Molecular Imaging, European Molecular Biology Laboratory (EMBL) Australia, Clayton, VIC 3800, Australia
| | - Don C Lamb
- Department of Chemistry, Center for NanoScience, Nanosystems Initiative Munich, Centre for Integrated Protein Science Munich, Ludwig Maximilian University of Munich, D-81377 Munich, Germany
| | - Roman Tuma
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, LS2 9JT Leeds, United Kingdom
- Faculty of Science, University of South Bohemia, 370 05 Ceske Budejovice, Czech Republic
| | - Antonio N Calabrese
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, LS2 9JT Leeds, United Kingdom
| | - Alexander Borodavka
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom;
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, LS2 9JT Leeds, United Kingdom
- Department of Chemistry, Center for NanoScience, Nanosystems Initiative Munich, Centre for Integrated Protein Science Munich, Ludwig Maximilian University of Munich, D-81377 Munich, Germany
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13
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Kanai Y, Kobayashi T. FAST Proteins: Development and Use of Reverse Genetics Systems for Reoviridae Viruses. Annu Rev Virol 2021; 8:515-536. [PMID: 34586868 DOI: 10.1146/annurev-virology-091919-070225] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Reverse genetics systems for viruses, the technology used to generate gene-engineered recombinant viruses from artificial genes, enable the study of the roles of the individual nucleotides and amino acids of viral genes and proteins in infectivity, replication, and pathogenicity. The successful development of a reverse genetics system for poliovirus in 1981 accelerated the establishment of protocols for other RNA viruses important for human health. Despite multiple efforts, rotavirus (RV), which causes severe gastroenteritis in infants, was refractory to reverse genetics analysis, and the first complete reverse genetics system for RV was established in 2017. This novel technique involves use of the fusogenic protein FAST (fusion-associated small transmembrane) derived from the bat-borne Nelson Bay orthoreovirus, which induces massive syncytium formation. Co-transfection of a FAST-expressing plasmid with complementary DNAs encoding RV genes enables rescue of recombinant RV. This review focuses on methodological insights into the reverse genetics system for RV and discusses applications and potential improvements to this system.
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Affiliation(s)
- Yuta Kanai
- Department of Virology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871, Japan; ,
| | - Takeshi Kobayashi
- Department of Virology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871, Japan; ,
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14
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Papa G, Burrone OR. Rotavirus reverse genetics: A tool for understanding virus biology. Virus Res 2021; 305:198576. [PMID: 34560180 DOI: 10.1016/j.virusres.2021.198576] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 09/08/2021] [Accepted: 09/15/2021] [Indexed: 10/25/2022]
Abstract
Rotaviruses (RVs) are considered to be one of the most common causes of viral gastroenteritis in young children and infants worldwide. Before recent developments, studies on rotavirus biology have suffered from the lack of an effective reverse genetics (RG) system to generate recombinant rotaviruses and study the precise roles of the viral proteins in the context of RV infection. Lately a fully-tractable plasmid-only based RG system for rescuing recombinant rotaviruses has been developed leading to a breakthrough in the RV field. Since then, the reproducibility and improvements of this technology have led to the generation of several recombinant rotaviruses with modifications on different gene segments, which has allowed the manipulation of viral genes to characterise the precise roles of viral proteins during RV replication cycle or to encode exogenous proteins for different purposes. This review will recapitulate the different RG approaches developed so far, highlighting any similarities, differences and limitations of the systems as well as the gene segments involved. The review will further summarise the latest recombinant rotaviruses generated using the plasmid-only based RG system showing the enormous potentials of this technique to shed light on the still unanswered questions in rotavirus biology.
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Affiliation(s)
- Guido Papa
- Molecular Immunology Laboratory, International Center for Genetic Engineering and Biotechnology, Padriciano 99, Trieste, Italy.
| | - Oscar R Burrone
- Molecular Immunology Laboratory, International Center for Genetic Engineering and Biotechnology, Padriciano 99, Trieste, Italy.
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15
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Human Rotavirus Reverse Genetics Systems to Study Viral Replication and Pathogenesis. Viruses 2021; 13:v13091791. [PMID: 34578372 PMCID: PMC8473093 DOI: 10.3390/v13091791] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 09/04/2021] [Accepted: 09/05/2021] [Indexed: 11/19/2022] Open
Abstract
Human rotaviruses (HuRVAs) are highly important causes of acute gastroenteritis in infants and young children worldwide. A lack of reliable and reproducible reverse genetics systems for HuRVAs has limited a proper understanding of HuRVA biology and also the rational design of live-attenuated vaccines. Since the development of the first reverse genetics system for RVAs (partially plasmid-based reverse genetics system) in 2006, there have been many efforts with the goal of generating infectious recombinant HuRVAs entirely from cloned cDNAs. However, the establishment of a HuRVA reverse genetics system was very challenging until 2019. This review article provides an overview of the historical background of the recent development of long-awaited HuRVA reverse genetics systems, beginning with the generation of recombinant human-simian reassortant RVAs with the aid of a helper virus in 2006 and the generation of recombinant animal (simian) RVAs in a helper virus-free manner in 2017, and culminating in the generation of recombinant HuRVAs entirely from plasmid cDNAs in 2019. Notably, the original HuRVA reverse genetics system has already been optimized to increase the efficiency of virus generation. Although the application of HuRVA reverse genetics systems has only just been initiated, these technologies will help to answer HuRVA research questions regarding viral replication and pathogenicity that could not be addressed before, and to develop next-generation vaccines and intestine-specific rotaviral vectors.
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16
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Tang N, Zhang Y, Shen Z, Yao Y, Nair V. Application of CRISPR-Cas9 Editing for Virus Engineering and the Development of Recombinant Viral Vaccines. CRISPR J 2021; 4:477-490. [PMID: 34406035 DOI: 10.1089/crispr.2021.0017] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
CRISPR-Cas technology, discovered originally as a bacterial defense system, has been extensively repurposed as a powerful tool for genome editing for multiple applications in biology. In the field of virology, CRISPR-Cas9 technology has been widely applied on genetic recombination and engineering of genomes of various viruses to ask some fundamental questions about virus-host interactions. Its high efficiency, specificity, versatility, and low cost have also provided great inspiration and hope in the field of vaccinology to solve a series of bottleneck problems in the development of recombinant viral vaccines. This review highlights the applications of CRISPR editing in the technological advances compared to the traditional approaches used for the construction of recombinant viral vaccines and vectors, the main factors affecting their application, and the challenges that need to be overcome for further streamlining their effective usage in the prevention and control of diseases. Factors affecting efficiency, target specificity, and fidelity of CRISPR-Cas editing in the context of viral genome editing and development of recombinant vaccines are also discussed.
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Affiliation(s)
- Na Tang
- Shandong Binzhou Animal Science and Veterinary Medicine Academy and UK-China Centre of Excellence for Research on Avian Diseases, Binzhou, P.R. China; University of Oxford, Oxford, United Kingdom
| | - Yaoyao Zhang
- The Pirbright Institute and UK-China Centre of Excellence for Research on Avian Diseases, Pirbright, Ash road, Guildford, Surrey, United Kingdom; University of Oxford, Oxford, United Kingdom
| | - Zhiqiang Shen
- Shandong Binzhou Animal Science and Veterinary Medicine Academy and UK-China Centre of Excellence for Research on Avian Diseases, Binzhou, P.R. China; University of Oxford, Oxford, United Kingdom
| | - Yongxiu Yao
- The Pirbright Institute and UK-China Centre of Excellence for Research on Avian Diseases, Pirbright, Ash road, Guildford, Surrey, United Kingdom; University of Oxford, Oxford, United Kingdom
| | - Venugopal Nair
- The Pirbright Institute and UK-China Centre of Excellence for Research on Avian Diseases, Pirbright, Ash road, Guildford, Surrey, United Kingdom; University of Oxford, Oxford, United Kingdom.,The Jenner Institute Laboratories, University of Oxford, Oxford, United Kingdom; and University of Oxford, Oxford, United Kingdom.,Department of Zoology, University of Oxford, Oxford, United Kingdom
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17
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Rotavirus viroplasm biogenesis involves microtubule-based dynein transport mediated by an interaction between NSP2 and dynein intermediate chain. J Virol 2021; 95:e0124621. [PMID: 34379449 DOI: 10.1128/jvi.01246-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Rotaviruses are the causative agents of severe and dehydrating gastroenteritis in children, piglets, and many other young animals. They replicate their genomes and assemble double-layered particles in cytoplasmic electron-dense inclusion bodies called 'viroplasms'. The formation of viroplasms is reportedly associated with the stability of microtubules. Although material transport is an important function of microtubules, whether and how microtubule-based transport influences the formation of viroplasms is still unclear. Here, we demonstrate that the small viroplasms move and fuse in living cells. We show that microtubule-based dynein transport affects rotavirus infection, viroplasm formation, and the assembly of transient enveloped particles (TEPs) and triple-layered particles (TLPs). The dynein intermediate chain (DIC) is shown to localize in the viroplasm and to interact directly with non-structural protein 2 (NSP2), indicating that DIC is responsible for connecting the viroplasm to dynein. The WD40 repeat domain of DIC regulates the interaction between DIC and NSP2, and the knockdown of DIC inhibited rotaviral infection, viroplasm formation, and the assembly of TEPs and TLPs. Our findings show that rotavirus viroplasms hijack dynein transport for fusion events, required for maximal assembly of infectious viral progeny. This study provides novel insights into the intracellular transport of viroplasms, which is involved in their biogenesis. Importance Because the viroplasm is the viral factory for rotavirus replication, viroplasm formation undoubtedly determines the effective production of progeny rotavirus. Therefore, understanding the virus-host interactions involved in the biogenesis of the viroplasm is critical for the future development of prophylactic and therapeutic strategies. Previous studies have reported that the formation of viroplasms is associated with the stability of microtubules, whereas little is known about its specific mechanism. Here, we demonstrate that rotavirus viroplasm formation takes advantage of microtubule-based dynein transport mediated by an interaction between NSP2 and DIC. These findings provide new insight into the intracellular transport of viroplasms.
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18
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Papa G, Borodavka A, Desselberger U. Viroplasms: Assembly and Functions of Rotavirus Replication Factories. Viruses 2021; 13:1349. [PMID: 34372555 PMCID: PMC8310052 DOI: 10.3390/v13071349] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 07/08/2021] [Accepted: 07/09/2021] [Indexed: 02/07/2023] Open
Abstract
Viroplasms are cytoplasmic, membraneless structures assembled in rotavirus (RV)-infected cells, which are intricately involved in viral replication. Two virus-encoded, non-structural proteins, NSP2 and NSP5, are the main drivers of viroplasm formation. The structures (as far as is known) and functions of these proteins are described. Recent studies using plasmid-only-based reverse genetics have significantly contributed to elucidation of the crucial roles of these proteins in RV replication. Thus, it has been recognized that viroplasms resemble liquid-like protein-RNA condensates that may be formed via liquid-liquid phase separation (LLPS) of NSP2 and NSP5 at the early stages of infection. Interactions between the RNA chaperone NSP2 and the multivalent, intrinsically disordered protein NSP5 result in their condensation (protein droplet formation), which plays a central role in viroplasm assembly. These droplets may provide a unique molecular environment for the establishment of inter-molecular contacts between the RV (+)ssRNA transcripts, followed by their assortment and equimolar packaging. Future efforts to improve our understanding of RV replication and genome assortment in viroplasms should focus on their complex molecular composition, which changes dynamically throughout the RV replication cycle, to support distinct stages of virion assembly.
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Affiliation(s)
- Guido Papa
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge CB2 0QH, UK;
| | | | - Ulrich Desselberger
- Department of Medicine, Addenbrooke’s Hospital, University of Cambridge, Cambridge CB2 0QQ, UK
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19
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Nilsson EM, Sullivan OM, Anderson ML, Argobright HM, Shue TM, Fedowitz FR, LaConte LEW, Esstman SM. Reverse genetic engineering of simian rotaviruses with temperature-sensitive lesions in VP1, VP2, and VP6. Virus Res 2021; 302:198488. [PMID: 34146610 DOI: 10.1016/j.virusres.2021.198488] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 05/24/2021] [Accepted: 06/10/2021] [Indexed: 10/21/2022]
Abstract
Rotaviruses are 11-segmented double-stranded RNA viruses and important causes of acute gastroenteritis in young children. To investigate the functions of specific viral proteins during the rotavirus lifecycle, temperature-sensitive (ts) mutants were previously created using a cultivatable simian strain (SA11) and chemical mutagenesis. These ts SA11 mutants replicate more efficiently at the permissive temperature of 31 °C than at the non-permissive temperature of 39 °C. Prototype strains SA11-tsC, SA11-tsF, and SA11-tsG were mapped to the genes encoding structural proteins VP1, VP2, and VP6, respectively, and putative ts lesions were identified using Sanger sequencing. However, additional background mutations in their genomes had hampered validation of the ts lesions and confounded their use in mechanistic studies. Here, we employed plasmid only-based reverse genetics to engineer recombinant (r) SA11 rotaviruses containing only the putative ts lesions of SA11-tsC (L138P change in VP1), SA11-tsF (A387D change in VP2) or SA11-tsG (S10T, D13H, and A121G changes in VP6). For simplicity, we refer to these newly-engineered, isogenic viruses as rSA11-tsVP1, rSA11-tsVP2, and rSA11-tsVP6. Single-cycle growth assays revealed that these mutants indeed exhibit ts phenotypes with significantly diminished titers (>1.5-logs) at 39 °C versus 31 °C. The rSA11 ts mutants proved genetically stable at the population-level following 3 sequential passages at 39 °C, but individual revertant clones were detected in plaque assays. Heat sensitivity experiments showed that pre-incubation of rSA11-tsVP1 or rSA11-tsVP2, but not rSA11-tsVP6, at 39 °C diminished replication at 31 °C. This result indicates that the ts lesions in VP1 and VP2 affect the incoming virion but those in VP6 affect a later stage of the viral lifecycle. In silico molecular dynamics simulations predicted temperature-dependent, long-range effects of the S10T, D13H, and/or A121G changes on the VP6 structure. Altogether, our results confirm the ts lesions of the original SA11-tsC, SA11-tsF, and SA11-tsG mutants, provide a new set of isogenic strains for investigating aspects of rotavirus replication, and shed light on how the ts lesions might impact VP1, VP2, or VP6 functions.
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Affiliation(s)
- Emil M Nilsson
- Department of Biology, Wake Forest University, Winston-Salem, NC, USA
| | - Owen M Sullivan
- Department of Biology, Wake Forest University, Winston-Salem, NC, USA
| | | | | | - Taylor M Shue
- Department of Biology, Wake Forest University, Winston-Salem, NC, USA
| | | | - Leslie E W LaConte
- Fralin Biomedical Research Institute, Roanoke, VA, USA; Department of Basic Science Education, Virginia Tech Carilion School of Medicine, Roanoke, VA, USA
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