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Optimal Conditions for In Vitro Assembly of Respiratory Syncytial Virus Nucleocapsid-like Particles. Viruses 2023; 15:v15020344. [PMID: 36851557 PMCID: PMC9962444 DOI: 10.3390/v15020344] [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] [Received: 12/24/2022] [Revised: 01/21/2023] [Accepted: 01/23/2023] [Indexed: 01/27/2023] Open
Abstract
The nucleocapsids (NCs) of the respiratory syncytial virus (RSV) can display multiple morphologies in vivo, including spherical, asymmetric, and filamentous conformations. Obtaining homogeneous ring-like oligomers in vitro is significant since they structurally represent one turn of the characteristic RSV NC helical filament. Here, we analyzed and optimized conditions for forming homogenous, recombinant nucleocapsid-like particles (NCLPs) of RSV in vitro. We examined the effects of modifying the integrated RNA length and sequence, altering incubation time, and varying buffer parameters, including salt concentration and pH, on ring-like NCLPs assembly using negative stain electron microscopy (EM) imaging. We showed that high-quality, homogeneous particles are assembled when incubating short, adenine-rich RNA sequences with RNA-free N associated with P (N0P). Further, we reported that a co-incubation duration greater than 3 days, a NaCl concentration between 100 mM and 200 mM, and a pH between 7 and 8 are optimal for N-RNA ring assembly with polyadenine RNA sequences. We believe assembling high-quality, homogeneous NCLPs in vitro will allow for further analysis of RSV RNA synthesis. This work may also lend insights into obtaining high-resolution nucleocapsid homogeneous structures for in vitro analysis of antiviral drug candidates against RSV and related viruses.
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2
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Cao D, Gooneratne I, Mera C, Vy J, Royal M, Huang B, Park Y, Manjunath A, Liang B. Analysis of Template Variations on RNA Synthesis by Respiratory Syncytial Virus Polymerase. Viruses 2022; 15:47. [PMID: 36680087 PMCID: PMC9863079 DOI: 10.3390/v15010047] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 12/18/2022] [Accepted: 12/21/2022] [Indexed: 12/28/2022] Open
Abstract
Respiratory syncytial virus (RSV) is a significant threat to infants and elderly individuals globally. Currently, there are no effective therapies or treatments for RSV infection because of an insufficient understanding of the RSV viral machinery. In this study, we investigated the effects of the template variations on RNA synthesis by the RSV polymerase through in vitro RNA synthesis assays. We confirmed the previously reported back-priming activity of the RSV polymerase, which is likely due to the secondary structure of the RNA template. We found that the expansion of the hairpin loop size of the RNA template abolishes the RSV polymerase back-priming activity. At the same time, it seemingly does not affect the de novo RNA synthesis activities of the RSV polymerase. Interestingly, our results show that the RSV polymerase also has a new primer-based terminal extension activity that adds nucleotides to the template and primer in a nonspecific manner. We also mapped the impact of the RNA 5' chemical group on its mobility in a urea-denaturing RNA gel shift assay. Overall, these results enhance our knowledge about the RNA synthesis processes of the RSV polymerase and may guide future therapeutic efforts to develop effective antiviral drugs for RSV treatment.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Bo Liang
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA
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3
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Gonnin L, Richard CA, Gutsche I, Chevret D, Troussier J, Vasseur JJ, Debart F, Eléouët JF, Galloux M. Importance of RNA length for in vitro encapsidation by the nucleoprotein of human Respiratory Syncytial Virus. J Biol Chem 2022; 298:102337. [PMID: 35931116 PMCID: PMC9436823 DOI: 10.1016/j.jbc.2022.102337] [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: 04/23/2022] [Revised: 07/21/2022] [Accepted: 07/22/2022] [Indexed: 11/29/2022] Open
Abstract
Respiratory syncytial virus has a negative-sense single-stranded RNA genome constitutively encapsidated by the viral nucleoprotein N, forming a helical nucleocapsid which is the template for viral transcription and replication by the viral polymerase L. Recruitment of L onto the nucleocapsid depends on the viral phosphoprotein P, which is an essential L cofactor. A prerequisite for genome and antigenome encapsidation is the presence of the monomeric, RNA-free, neosynthesized N protein, named N0. Stabilization of N0 depends on the binding of the N-terminal residues of P to its surface, which prevents N oligomerization. However, the mechanism involved in the transition from N0-P to nucleocapsid assembly, and thus in the specificity of viral genome encapsidation, is still unknown. Furthermore, the specific role of N oligomerization and RNA in the morphogenesis of viral factories, where viral transcription and replication occur, have not been elucidated although the interaction between P and N complexed to RNA has been shown to be responsible for this process. Here, using a chimeric protein comprising N and the first 40 N-terminal residues of P, we succeeded in purifying a recombinant N0-like protein competent for RNA encapsidation in vitro. Our results showed the importance of RNA length for stable encapsidation and revealed that the nature of the 5′ end of RNA does not explain the specificity of encapsidation. Finally, we showed that RNA encapsidation is crucial for the in vitro reconstitution of pseudo-viral factories. Together, our findings provide insight into respiratory syncytial virus viral genome encapsidation specificity.
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Affiliation(s)
- Lorène Gonnin
- Université Paris-Saclay, INRAE, UVSQ, VIM, Jouy-en-Josas, France
| | | | - Irina Gutsche
- University of Grenoble Alpes, CEA, CNRS, IBS, Grenoble, France
| | - Didier Chevret
- Université Paris-Saclay, INRAE, UVSQ, VIM, Jouy-en-Josas, France
| | - Joris Troussier
- IBMM, Université de Montpellier, ENSCM, CNRS, UMR 5247, Montpellier, France
| | | | - Françoise Debart
- IBMM, Université de Montpellier, ENSCM, CNRS, UMR 5247, Montpellier, France
| | | | - Marie Galloux
- Université Paris-Saclay, INRAE, UVSQ, VIM, Jouy-en-Josas, France.
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4
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Stokes AH, Planty C, Pion J, Ancian P, Rogue A, Bansard C, Silvano J, Papineau D, Ben Abdeljelil N, Maruggi G, Song H, Spickler C, Blouin K, Dubois G, Rodriguez LA, Baumeister J, Steff AM, Destexhe E. Repeated-Dose Toxicity, Biodistribution, and Shedding Assessments With a ChAd155 Respiratory Syncytial Virus Vaccine Candidate Evaluated in Rabbits and Rats. Int J Toxicol 2022; 41:263-275. [PMID: 35653115 DOI: 10.1177/10915818221101788] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Respiratory syncytial virus (RSV) is a leading cause of acute lower respiratory tract infections (LRTI) in infants, and toddlers and vaccines are not yet available. A pediatric RSV vaccine (ChAd155-RSV) is being developed to protect infants against RSV disease. The ChAd155-RSV vaccine consists of a recombinant replication-deficient chimpanzee-derived adenovirus (ChAd) group C vector engineered to express the RSV antigens F, N, and M2-1. The local and systemic effects of three bi-weekly intramuscular injections of the ChAd155-RSV vaccine was tested in a repeated-dose toxicity study in rabbits. After three intramuscular doses, the ChAd155-RSV vaccine was considered well-tolerated. Changes due to the vaccine-elicited inflammatory reaction/immune response were observed along with transient decreases in platelet count without physiological consequences, already reported for other adenovirus-based vaccines. In addition, the biodistribution and shedding of ChAd155-RSV were also characterized in two studies in rats. The distribution and persistence of the ChAd155-RSV vaccine candidate was consistent with other similar adenovector-based vaccines, with quantifiable levels of ChAd155-RSV observed at the injection site (muscle) and the draining lymph nodes up to 69 days post administration. The shedding results demonstrated that ChAd155-RSV was generally not detectable in any secretions or excreta samples. In conclusion, the ChAd155-RSV vaccine was well-tolerated locally and systemically.
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Affiliation(s)
| | - Camille Planty
- 33139GSK, Rixensart, Belgium.,Current affiliation: CapGemini Engineering, Brussels, Belgium
| | - Johanne Pion
- Charles River Laboratories, Laval (Québec), Canada
| | | | | | | | | | | | | | | | - Haifeng Song
- 33139GSK, Rockville, MD, USA.,Current affiliation: Suzhou Abogen Bioscience Ltd, Suzhou (Jiangsu), China
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5
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Conley MJ, Short JM, Burns AM, Streetley J, Hutchings J, Bakker SE, Power BJ, Jaffery H, Haney J, Zanetti G, Murcia PR, Stewart M, Fearns R, Vijayakrishnan S, Bhella D. Helical ordering of envelope-associated proteins and glycoproteins in respiratory syncytial virus. EMBO J 2022; 41:e109728. [PMID: 34935163 PMCID: PMC8804925 DOI: 10.15252/embj.2021109728] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 12/01/2021] [Accepted: 12/03/2021] [Indexed: 12/20/2022] Open
Abstract
Human respiratory syncytial virus (RSV) causes severe respiratory illness in children and the elderly. Here, using cryogenic electron microscopy and tomography combined with computational image analysis and three-dimensional reconstruction, we show that there is extensive helical ordering of the envelope-associated proteins and glycoproteins of RSV filamentous virions. We calculated a 16 Å resolution sub-tomogram average of the matrix protein (M) layer that forms an endoskeleton below the viral envelope. These data define a helical lattice of M-dimers, showing how M is oriented relative to the viral envelope. Glycoproteins that stud the viral envelope were also found to be helically ordered, a property that was coordinated by the M-layer. Furthermore, envelope glycoproteins clustered in pairs, a feature that may have implications for the conformation of fusion (F) glycoprotein epitopes that are the principal target for vaccine and monoclonal antibody development. We also report the presence, in authentic virus infections, of N-RNA rings packaged within RSV virions. These data provide molecular insight into the organisation of the virion and the mechanism of its assembly.
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Affiliation(s)
- Michaela J Conley
- Medical Research Council – University of Glasgow Centre for Virus ResearchGlasgowUK
| | - Judith M Short
- Medical Research Council Laboratory of Molecular BiologyCambridgeUK
| | - Andrew M Burns
- Medical Research Council – University of Glasgow Centre for Virus ResearchGlasgowUK
| | - James Streetley
- Medical Research Council – University of Glasgow Centre for Virus ResearchGlasgowUK
| | - Joshua Hutchings
- Department of Biological SciencesBirkbeck CollegeLondonUK
- Present address:
Division of Biological SciencesUniversity of California San DiegoLa JollaCAUSA
| | - Saskia E Bakker
- Medical Research Council – University of Glasgow Centre for Virus ResearchGlasgowUK
- Present address:
School of Life SciencesUniversity of WarwickCoventryUK
| | - B Joanne Power
- Medical Research Council – University of Glasgow Centre for Virus ResearchGlasgowUK
- Present address:
Department of Biochemistry and Molecular BiologyThe Huck Center for Malaria ResearchPennsylvania State UniversityUniversity ParkPAUSA
| | - Hussain Jaffery
- Medical Research Council – University of Glasgow Centre for Virus ResearchGlasgowUK
| | - Joanne Haney
- Medical Research Council – University of Glasgow Centre for Virus ResearchGlasgowUK
| | - Giulia Zanetti
- Department of Biological SciencesBirkbeck CollegeLondonUK
| | - Pablo R Murcia
- Medical Research Council – University of Glasgow Centre for Virus ResearchGlasgowUK
| | - Murray Stewart
- Medical Research Council Laboratory of Molecular BiologyCambridgeUK
| | - Rachel Fearns
- Department of MicrobiologyBoston University School of MedicineBostonMAUSA
- National Emerging Infectious Diseases LaboratoriesBoston UniversityBostonMAUSA
| | | | - David Bhella
- Medical Research Council – University of Glasgow Centre for Virus ResearchGlasgowUK
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The Nucleocapsid of Paramyxoviruses: Structure and Function of an Encapsidated Template. Viruses 2021; 13:v13122465. [PMID: 34960734 PMCID: PMC8708338 DOI: 10.3390/v13122465] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 12/07/2021] [Accepted: 12/07/2021] [Indexed: 01/28/2023] Open
Abstract
Viruses of the Paramyxoviridae family share a common and complex molecular machinery for transcribing and replicating their genomes. Their non-segmented, negative-strand RNA genome is encased in a tight homopolymer of viral nucleoproteins (N). This ribonucleoprotein complex, termed a nucleocapsid, is the template of the viral polymerase complex made of the large protein (L) and its co-factor, the phosphoprotein (P). This review summarizes the current knowledge on several aspects of paramyxovirus transcription and replication, including structural and functional data on (1) the architecture of the nucleocapsid (structure of the nucleoprotein, interprotomer contacts, interaction with RNA, and organization of the disordered C-terminal tail of N), (2) the encapsidation of the genomic RNAs (structure of the nucleoprotein in complex with its chaperon P and kinetics of RNA encapsidation in vitro), and (3) the use of the nucleocapsid as a template for the polymerase complex (release of the encased RNA and interaction network allowing the progress of the polymerase complex). Finally, this review presents models of paramyxovirus transcription and replication.
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Structural Insights into the Respiratory Syncytial Virus RNA Synthesis Complexes. Viruses 2021; 13:v13050834. [PMID: 34063087 PMCID: PMC8147935 DOI: 10.3390/v13050834] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 04/30/2021] [Accepted: 05/02/2021] [Indexed: 12/13/2022] Open
Abstract
RNA synthesis in respiratory syncytial virus (RSV), a negative-sense (-) nonsegmented RNA virus, consists of viral gene transcription and genome replication. Gene transcription includes the positive-sense (+) viral mRNA synthesis, 5'-RNA capping and methylation, and 3' end polyadenylation. Genome replication includes (+) RNA antigenome and (-) RNA genome synthesis. RSV executes the viral RNA synthesis using an RNA synthesis ribonucleoprotein (RNP) complex, comprising four proteins, the nucleoprotein (N), the large protein (L), the phosphoprotein (P), and the M2-1 protein. We provide an overview of the RSV RNA synthesis and the structural insights into the RSV gene transcription and genome replication process. We propose a model of how the essential four proteins coordinate their activities in different RNA synthesis processes.
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