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Zhao B, Hu L, Kaundal S, Neetu N, Lee CH, Somoulay X, Sankaran B, Taylor GM, Dermody TS, Venkataram Prasad BV. Structure of orthoreovirus RNA chaperone σNS, a component of viral replication factories. Nat Commun 2024; 15:2460. [PMID: 38503747 PMCID: PMC10950856 DOI: 10.1038/s41467-024-46627-8] [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: 08/25/2023] [Accepted: 02/29/2024] [Indexed: 03/21/2024] Open
Abstract
The mammalian orthoreovirus (reovirus) σNS protein is required for formation of replication compartments that support viral genome replication and capsid assembly. Despite its functional importance, a mechanistic understanding of σNS is lacking. We conducted structural and biochemical analyses of a σNS mutant that forms dimers instead of the higher-order oligomers formed by wildtype (WT) σNS. The crystal structure shows that dimers interact with each other using N-terminal arms to form a helical assembly resembling WT σNS filaments in complex with RNA observed using cryo-EM. The interior of the helical assembly is of appropriate diameter to bind RNA. The helical assembly is disrupted by bile acids, which bind to the same site as the N-terminal arm. This finding suggests that the N-terminal arm functions in conferring context-dependent oligomeric states of σNS, which is supported by the structure of σNS lacking an N-terminal arm. We further observed that σNS has RNA chaperone activity likely essential for presenting mRNA to the viral polymerase for genome replication. This activity is reduced by bile acids and abolished by N-terminal arm deletion, suggesting that the activity requires formation of σNS oligomers. Our studies provide structural and mechanistic insights into the function of σNS in reovirus replication.
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Affiliation(s)
- Boyang Zhao
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA
| | - Liya Hu
- Verna and Marrs Mclean Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, TX, USA
| | - Soni Kaundal
- Verna and Marrs Mclean Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, TX, USA
| | - Neetu Neetu
- Verna and Marrs Mclean Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, TX, USA
| | - Christopher H Lee
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburg, PA, USA
- Institute of Infection, Inflammation, and Immunity, UPMC Children's Hospital of Pittsburgh, Pittsburg, PA, USA
| | - Xayathed Somoulay
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburg, PA, USA
- Institute of Infection, Inflammation, and Immunity, UPMC Children's Hospital of Pittsburgh, Pittsburg, PA, USA
| | - Banumathi Sankaran
- Berkeley Center for Structural Biology, Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley Laboratory, Berkeley, CA, USA
| | - Gwen M Taylor
- Institute of Infection, Inflammation, and Immunity, UPMC Children's Hospital of Pittsburgh, Pittsburg, PA, USA
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburg, PA, USA
| | - Terence S Dermody
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburg, PA, USA.
- Institute of Infection, Inflammation, and Immunity, UPMC Children's Hospital of Pittsburgh, Pittsburg, PA, USA.
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburg, PA, USA.
| | - B V Venkataram Prasad
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX, USA.
- Verna and Marrs Mclean Department of Biochemistry and Molecular Pharmacology, Baylor College of Medicine, Houston, TX, USA.
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Smith SC, Krystofiak E, Ogden KM. Mammalian orthoreovirus can exit cells in extracellular vesicles. PLoS Pathog 2024; 20:e1011637. [PMID: 38206991 PMCID: PMC10807757 DOI: 10.1371/journal.ppat.1011637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 01/24/2024] [Accepted: 01/02/2024] [Indexed: 01/13/2024] Open
Abstract
Several egress pathways have been defined for many viruses. Among these pathways, extracellular vesicles (EVs) have been shown to function as vehicles of non-lytic viral egress. EVs are heterogenous populations of membrane-bound structures released from cells as a form of intercellular communication. EV-mediated viral egress may enable immune evasion and collective viral transport. Strains of nonenveloped mammalian orthoreovirus (reovirus) differ in cell lysis phenotypes, with T3D disrupting cell membranes more efficiently than T1L. However, mechanisms of reovirus egress and the influence of transport strategy on infection are only partially understood. To elucidate reovirus egress mechanisms, we infected murine fibroblasts (L cells) and non-polarized human colon epithelial (Caco-2) cells with T1L or T3D reovirus and enriched cell culture supernatants for large EVs, medium EVs, small EVs, and free reovirus. We found that both reovirus strains exit cells in association with large and medium EVs and as free virus particles, and that EV-enriched fractions are infectious. While reovirus visually associates with large and medium EVs, only medium EVs offer protection from antibody-mediated neutralization. EV-mediated protection from neutralization is virus strain- and cell type-specific, as medium EVs enriched from L cell supernatants protect T1L and T3D, while medium EVs enriched from Caco-2 cell supernatants largely fail to protect T3D and only protect T1L efficiently. Using genetically barcoded reovirus, we provide evidence that large and medium EVs can convey multiple particles to recipient cells. Finally, T1L or T3D infection increases the release of all EV sizes from L cells. Together, these findings suggest that in addition to exiting cells as free particles, reovirus promotes egress from distinct cell types in association with large and medium EVs during lytic or non-lytic infection, a mode of exit that can mediate multiparticle infection and, in some cases, protection from antibody neutralization.
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Affiliation(s)
- Sydni Caet Smith
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Evan Krystofiak
- Department of Cell & Developmental Biology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Kristen M. Ogden
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
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Nour I, Alvarez-Narvaez S, Harrell TL, Conrad SJ, Mohanty SK. Whole Genomic Constellation of Avian Reovirus Strains Isolated from Broilers with Arthritis in North Carolina, USA. Viruses 2023; 15:2191. [PMID: 38005869 PMCID: PMC10675200 DOI: 10.3390/v15112191] [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: 09/30/2023] [Revised: 10/26/2023] [Accepted: 10/28/2023] [Indexed: 11/26/2023] Open
Abstract
Avian reovirus (ARV) is an emerging pathogen which causes significant economic challenges to the chicken and turkey industry in the USA and globally, yet the molecular characterization of most ARV strains is restricted to a single particular gene, the sigma C gene. The genome of arthrogenic reovirus field isolates (R18-37308 and R18-38167), isolated from broiler chickens in North Carolina (NC), USA in 2018, was sequenced using long-read next-generation sequencing (NGS). The isolates were genotyped based on the amino acid sequence of sigma C (σC) followed by phylogenetic and amino acid analyses of the other 11 genomically encoded proteins for whole genomic constellation and genetic variation detection. The genomic length of the NC field strains was 23,494 bp, with 10 dsRNA segments ranging from 3959 bp (L1) to 1192 bp (S4), and the 5' and 3' untranslated regions (UTRs) of all the segments were found to be conserved. R18-37308 and R18-38167 were found to belong to genotype (G) VI based on the σC analysis and showed nucleotide and amino acid sequence identity ranging from 84.91-98.47% and 83.43-98.46%, respectively, with G VI strains. Phylogenetic analyses of individual genes of the NC strains did not define a single common ancestor among the available completely sequenced ARV strains. Nevertheless, most sequences supported the Chinese strain LY383 as a probable ancestor of these isolates. Moreover, amino acid analysis revealed multiple amino acid substitution events along the entirety of the genes, some of which were unique to each strain, which suggests significant divergence owing to the accumulation of point mutations. All genes from R18-37308 and R18-38167 were found to be clustered within genotypic clusters that included only ARVs of chicken origin, which negates the possibility of genetic pooling or host variation. Collectively, this study revealed sequence divergence between the NC field strains and reference ARV strains, including the currently used vaccine strains could help updating the vaccination regime through the inclusion of these highly divergent circulating indigenous field isolates.
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Affiliation(s)
| | | | | | | | - Sujit K. Mohanty
- United States Department of Agriculture, Agricultural Research Service (USDA-ARS), US National Poultry Research Center, Athens, GA 30605, USA; (I.N.); (S.A.-N.); (T.L.H.); (S.J.C.)
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Khaleafi R, Zeleznjak J, Cordela S, Drucker S, Rovis TL, Jonjic S, Bar-On Y. Reovirus infection of tumor cells reduces the expression of NKG2D ligands, leading to impaired NK-cell cytotoxicity and functionality. Front Immunol 2023; 14:1231782. [PMID: 37753084 PMCID: PMC10518469 DOI: 10.3389/fimmu.2023.1231782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Accepted: 08/24/2023] [Indexed: 09/28/2023] Open
Abstract
In recent years, reoviruses have been of major interest in immunotherapy because of their oncolytic properties. Preclinical and clinical trials, in which reovirus was used for the treatment of melanoma and glioblastoma, have paved the way for future clinical use of reovirus. However, little is known about how reovirus infection affects the tumor microenvironment and immune response towards infected tumor cells. Studies have shown that reovirus can directly stimulate natural killer (NK) cells, but how reovirus affects cellular ligands on tumor cells, which are ultimately key to tumor recognition and elimination by NK cells, has not been investigated. We tested how reovirus infection affects the binding of the NK Group-2 member D (NKG2D) receptor, which is a dominant mediator of NK cell anti-tumor activity. Using models of human-derived melanoma and glioblastoma tumors, we demonstrated that NKG2D ligands are downregulated in tumor cells post-reovirus-infection due to the impaired translation of these ligands in reovirus-infected cells. Moreover, we showed that downregulation of NKG2D ligands significantly impaired the binding of NKG2D to infected tumor cells. We further demonstrated that reduced recognition of NKG2D ligands significantly alters NK cell anti-tumor cytotoxicity in human primary NK cells and in the NK cell line NK-92. Thus, this study provides novel insights into reovirus-host interactions and could lead to the development of novel reovirus-based therapeutics that enhance the anti-tumor immune response.
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Affiliation(s)
- Raghad Khaleafi
- Department of Immunology, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Jelena Zeleznjak
- Department of Histology and Embryology/Center for Proteomics, Faculty of Medicine, University of Rijeka, Rijeka, Croatia
| | - Sapir Cordela
- Department of Immunology, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Shani Drucker
- Department of Immunology, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Tihana Lenac Rovis
- Department of Histology and Embryology/Center for Proteomics, Faculty of Medicine, University of Rijeka, Rijeka, Croatia
| | - Stipan Jonjic
- Department of Histology and Embryology/Center for Proteomics, Faculty of Medicine, University of Rijeka, Rijeka, Croatia
| | - Yotam Bar-On
- Department of Immunology, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
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5
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Zhao B, Hu L, Kuandal S, Neetu N, Lee C, Somoulay X, Sankaran B, Taylor GM, Dermody TS, Prasad BVV. Structure of Orthoreovirus RNA Chaperone σNS, a Component of Viral Replication Factories. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.31.551319. [PMID: 37577609 PMCID: PMC10418060 DOI: 10.1101/2023.07.31.551319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
The reovirus σNS RNA-binding protein is required for formation of intracellular compartments during viral infection that support viral genome replication and capsid assembly. Despite its functional importance, a mechanistic understanding of σNS is lacking. We conducted structural and biochemical analyses of an R6A mutant of σNS that forms dimers instead of the higher-order oligomers formed by wildtype (WT) σNS. The crystal structure of selenomethionine-substituted σNS-R6A reveals that the mutant protein forms a stable antiparallel dimer, with each subunit having a well-folded central core and a projecting N-terminal arm. The dimers interact with each other by inserting the N-terminal arms into a hydrophobic pocket of the neighboring dimers on either side to form a helical assembly that resembles filaments of WT σNS in complex with RNA observed using cryo-EM. The interior of the crystallographic helical assembly is positively charged and of appropriate diameter to bind RNA. The helical assembly is disrupted by bile acids, which bind to the same hydrophobic pocket as the N-terminal arm, as demonstrated in the crystal structure of σNS-R6A in complex with bile acid, suggesting that the N-terminal arm functions in conferring context-dependent oligomeric states of σNS. This idea is supported by the structure of σNS lacking the N-terminal arm. We discovered that σNS displays RNA helix destabilizing and annealing activities, likely essential for presenting mRNA to the viral RNA-dependent RNA polymerase for genome replication. The RNA chaperone activity is reduced by bile acids and abolished by N-terminal arm deletion, suggesting that the activity requires formation of σNS oligomers. Our studies provide structural and mechanistic insights into the function of σNS in reovirus replication.
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Shang P, Simpson JD, Taylor GM, Sutherland DM, Welsh OL, Aravamudhan P, Natividade RDS, Schwab K, Michel JJ, Poholek AC, Wu Y, Rajasundaram D, Koehler M, Alsteens D, Dermody TS. Paired immunoglobulin-like receptor B is an entry receptor for mammalian orthoreovirus. Nat Commun 2023; 14:2615. [PMID: 37147336 PMCID: PMC10163058 DOI: 10.1038/s41467-023-38327-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 04/25/2023] [Indexed: 05/07/2023] Open
Abstract
Mammalian orthoreovirus (reovirus) infects most mammals and is associated with celiac disease in humans. In mice, reovirus infects the intestine and disseminates systemically to cause serotype-specific patterns of disease in the brain. To identify receptors conferring reovirus serotype-dependent neuropathogenesis, we conducted a genome-wide CRISPRa screen and identified paired immunoglobulin-like receptor B (PirB) as a receptor candidate. Ectopic expression of PirB allowed reovirus binding and infection. PirB extracelluar D3D4 region is required for reovirus attachment and infectivity. Reovirus binds to PirB with nM affinity as determined by single molecule force spectroscopy. Efficient reovirus endocytosis requires PirB signaling motifs. In inoculated mice, PirB is required for maximal replication in the brain and full neuropathogenicity of neurotropic serotype 3 (T3) reovirus. In primary cortical neurons, PirB expression contributes to T3 reovirus infectivity. Thus, PirB is an entry receptor for reovirus and contributes to T3 reovirus replication and pathogenesis in the murine brain.
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Affiliation(s)
- Pengcheng Shang
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Institute of Infection, Inflammation, and Immunity, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, USA
| | - Joshua D Simpson
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Gwen M Taylor
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Institute of Infection, Inflammation, and Immunity, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, USA
| | - Danica M Sutherland
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Institute of Infection, Inflammation, and Immunity, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, USA
| | - Olivia L Welsh
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Institute of Infection, Inflammation, and Immunity, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, USA
| | - Pavithra Aravamudhan
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Institute of Infection, Inflammation, and Immunity, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, USA
| | - Rita Dos Santos Natividade
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Kristina Schwab
- Department of Immunology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Joshua J Michel
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Amanda C Poholek
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Department of Immunology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Yijen Wu
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Dhivyaa Rajasundaram
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Melanie Koehler
- Leibniz Institute for Food Systems Biology at the Technical University Munich, Freising, Germany
| | - David Alsteens
- Louvain Institute of Biomolecular Science and Technology, Université catholique de Louvain, Louvain-la-Neuve, Belgium
- WELBIO Department, WEL Research Institute, Wavre, Belgium
| | - Terence S Dermody
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
- Institute of Infection, Inflammation, and Immunity, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, USA.
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
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p17-modulated Hsp90/Cdc37 complex governs oncolytic avian reovirus replication by chaperoning p17 that promotes viral protein synthesis and accumulation of viral proteins σC and σA in viral factories. J Virol 2022; 96:e0007422. [PMID: 35107368 DOI: 10.1128/jvi.00074-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In this work we have determined that heat shock protein 90 (Hsp90) is essential for avian reovirus (ARV) replication by chaperoning the ARV p17 protein. p17 modulates the formation of the Hsp90/Cdc37 complex by phosphorylation of Cdc37 and this chaperone machinery protects p17 from ubiquitin-proteasome degradation. Iinhibition of the Hsp90/Cdc37 complex by inhibitors (17-AAG and celastrol) or shRNAs significantly reduced expression levels of viral proteins and virus yield, suggesting that the Hsp90/Cdc37 chaperone complex functions in virus replication. The expression levels of p17 were decreased at the examined time points (2-7 and 7-16 hours) in 17-AAG-treated cells in a dose-dependent manner while the expression levels of viral proteins σA, σC, and σNS were decreased at the examined time point (7-16 hours). Interestingly, the expression levels of σC, σA, and σNS proteins increased along with co-expression of p17 protein. p17 together with the Hsp90/Cdc37 complex do not increase viral genome replication, but enhance viral protein stability, maturation, and virus production. Virus factories of ARV are composed of non-structural proteins σNS and μNS. We found that the Hsp90/Cdc37chaperone plays an important role in accumulation of the outer-capsid protein σC, inner core protein σA, and non-structural protein σNS of ARV in viral factories. Depletion of Hsp90 inhibited σA, σC, and p17 proteins colocalized with σNS in viral factories. This study provides novel insights into p17-modulated formation of the Hsp90/Cdc37 chaperone complex governing virus replication via stabilization and maturation of viral proteins and accumulation of viral proteins in viral factories for virus assembly. IMPORTANCE Molecular mechanisms that control stabilization of ARV proteins and the intermolecular interactions among inclusion components remain largely unknown. Here, we show that the ARV p17 is a Hsp90 client protein. The Hsp90/Cdc37 complex is essential for ARV replication by protecting p17 from ubiquitin-proteasome degradation. p17 modulates the formation of Hsp90/Cdc37 complex by phosphorylation of Cdc37 and this chaperone machinery protects p17 from ubiquitin-proteasome degradation, suggesting a feedback loop between p17 and the Hsp90/Cdc37 complex. p17 together with the Hsp90/Cdc37 complex do not increase viral genome replication, but enhance viral protein stability and virus production. Depletion of Hsp90 prevented viral proteins σA, σC, and p17 colocalized with σNS in viral factories. Our findings elucidate that the Hsp90/Cdc37 complex chaperones p17 which, in turn, promotes the synthesis of viral proteins σA, σC, and σNS and facilitates accumulation of the outer-capsid protein σC and inner core protein σA in viral factories for virus assembly.
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Huang WR, Li JY, Liao TL, Yeh CM, Wang CY, Wen HW, Hu NJ, Wu YY, Hsu CY, Chang YK, Chang CD, Nielsen BL, Liu HJ. Molecular chaperone TRiC governs avian reovirus replication by protecting outer-capsid protein σC and inner core protein σA and non-structural protein σNS from ubiquitin- proteasome degradation. Vet Microbiol 2021; 264:109277. [PMID: 34826648 DOI: 10.1016/j.vetmic.2021.109277] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 10/27/2021] [Accepted: 11/07/2021] [Indexed: 01/15/2023]
Abstract
Avian reoviruses (ARVs) are important pathogens that cause considerable economic losses in poultry farming. To date, host factors that control stabilization of ARV proteins remain largely unknown. In this work we determined that the eukaryotic chaperonin T-complex protein-1 (TCP-1) ring complex (TRiC) is essential for avian reovirus (ARV) replication by stabilizing outer-capsid protein σC, inner core protein σA, and the non-structural protein σNS of ARV. TriC serves as a chaperone of viral proteins and prevent their degradation via the ubiquitin-proteasome pathway. Furthermore, reciprocal co-immunoprecipitation assays confirmed the association of viral proteins (σA, σC, and σNS) with TRiC. Immunofluorescence staining indicated that the TRiC chaperonins (CCT2 and CCT5) are colocalized with viral proteins σC, σA, and σNS of ARV. In this study, inhibition of TRiC chaperonins (CCT2 and CCT5) by the inhibitor HSF1A or shRNAs significantly reduced expression levels of the σC, σA, and σNS proteins of ARV as well as virus yield, suggesting that the TRiC complex functions in stabilization of viral proteins and virus replication. This study provides novel insights into TRiC chaperonin governing virus replication via stabilization of outer-capsid protein σC, inner core protein σA, and the non-structural protein σNS of ARV.
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Affiliation(s)
- Wei-Ru Huang
- Institute of Molecular Biology, National Chung Hsing University, Taichung, Taiwan; The iEGG and Animal Biotechnology Center, National Chung Hsing University, Taichung, Taiwan
| | - Jyun-Yi Li
- Institute of Molecular Biology, National Chung Hsing University, Taichung, Taiwan; The iEGG and Animal Biotechnology Center, National Chung Hsing University, Taichung, Taiwan
| | - Tsai-Ling Liao
- Department of Medical Research, Taichung Veterans General Hospital, Taichung, Taiwan; Rong Hsing Research Center for Translational Medicine, National Chung Hsing University, Taichung, Taiwan; Ph.D Program in Translational Medicine, National Chung Hsing University, Taichung, 402, Taiwan
| | - Chuan-Ming Yeh
- Institute of Molecular Biology, National Chung Hsing University, Taichung, Taiwan; Bioproduction Reearch Institute, National Institute of Advanced Industrial Science and Technology, Tsukaba, Japan
| | - Chi-Young Wang
- The iEGG and Animal Biotechnology Center, National Chung Hsing University, Taichung, Taiwan; Department of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan
| | - Hsiao-Wei Wen
- Department of Food Science and Biotechnology, National Chung Hsing University, Taichung, Taiwan
| | - Nien-Jen Hu
- Institute of Biochemistry, National Chung Hsing University, Taichung, Taiwan
| | - Yi-Ying Wu
- Institute of Molecular Biology, National Chung Hsing University, Taichung, Taiwan; The iEGG and Animal Biotechnology Center, National Chung Hsing University, Taichung, Taiwan
| | - Chao-Yu Hsu
- Ph.D Program in Translational Medicine, National Chung Hsing University, Taichung, 402, Taiwan; Division of Urology, Department of Surgery, Tung's Taichung MetroHarbor Hospital, Taichung, Taiwan
| | - Yu-Kang Chang
- Department of Medical Research, Tung's Taichung MetroHarbor Hospital, Taichung, Taiwan; Depertment of Nursing, Jen-Teh Junior College of Medicine and Management, Taiwan
| | - Ching-Dong Chang
- Department of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung, Taiwan
| | - Brent L Nielsen
- Department of Microbiology and Molecular Biology, Brigham Young University, Provo, UT, USA
| | - Hung-Jen Liu
- Institute of Molecular Biology, National Chung Hsing University, Taichung, Taiwan; The iEGG and Animal Biotechnology Center, National Chung Hsing University, Taichung, Taiwan; Rong Hsing Research Center for Translational Medicine, National Chung Hsing University, Taichung, Taiwan; Ph.D Program in Translational Medicine, National Chung Hsing University, Taichung, 402, Taiwan; Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan.
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9
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Guo Y, Hinchman MM, Lewandrowski M, Cross ST, Sutherland DM, Welsh OL, Dermody TS, Parker JSL. The multi-functional reovirus σ3 protein is a virulence factor that suppresses stress granule formation and is associated with myocardial injury. PLoS Pathog 2021; 17:e1009494. [PMID: 34237110 PMCID: PMC8291629 DOI: 10.1371/journal.ppat.1009494] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 07/20/2021] [Accepted: 06/21/2021] [Indexed: 11/19/2022] Open
Abstract
The mammalian orthoreovirus double-stranded (ds) RNA-binding protein σ3 is a multifunctional protein that promotes viral protein synthesis and facilitates viral entry and assembly. The dsRNA-binding capacity of σ3 correlates with its capacity to prevent dsRNA-mediated activation of protein kinase R (PKR). However, the effect of σ3 binding to dsRNA during viral infection is largely unknown. To identify functions of σ3 dsRNA-binding activity during reovirus infection, we engineered a panel of thirteen σ3 mutants and screened them for the capacity to bind dsRNA. Six mutants were defective in dsRNA binding, and mutations in these constructs cluster in a putative dsRNA-binding region on the surface of σ3. Two recombinant viruses expressing these σ3 dsRNA-binding mutants, K287T and R296T, display strikingly different phenotypes. In a cell-type dependent manner, K287T, but not R296T, replicates less efficiently than wild-type (WT) virus. In cells in which K287T virus demonstrates a replication deficit, PKR activation occurs and abundant stress granules (SGs) are formed at late times post-infection. In contrast, the R296T virus retains the capacity to suppress activation of PKR and does not mediate formation of SGs at late times post-infection. These findings indicate that σ3 inhibits PKR independently of its capacity to bind dsRNA. In infected mice, K287T produces lower viral titers in the spleen, liver, lungs, and heart relative to WT or R296T. Moreover, mice inoculated with WT or R296T viruses develop myocarditis, whereas those inoculated with K287T do not. Overall, our results indicate that σ3 functions to suppress PKR activation and subsequent SG formation during viral infection and that these functions correlate with virulence in mice. The σ3 protein of mammalian orthoreoviruses is a double-stranded RNA binding protein that has classically been thought to function by scavenging dsRNA within infected cells and thus prevents activation of cellular sensors of dsRNA such as the kinase PKR. Here we used mutagenesis to identify the region of σ3 responsible for binding dsRNA. Characterization of mutant viruses expressing σ3 proteins incapable of binding dsRNA show that contrary to expectation, dsRNA binding is not required for σ3-mediated inhibition of PKR. We show that one mutant virus (R296T) despite being deficient in dsRNA-binding can inhibit PKR and replicates similar to WT virus. In contrast, another mutant virus (K287T) that bears a σ3 protein that cannot prevent dsRNA-mediated activation of PKR induces stress granules in infected cells and replicates less efficiently than WT virus. In vivo, the K287T mutant is attenuated in its replication and unlike WT virus and the R296T mutant virus does not cause heart disease (myocarditis).
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Affiliation(s)
- Yingying Guo
- Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States of America
| | - Meleana M. Hinchman
- Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States of America
| | - Mercedes Lewandrowski
- Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States of America
| | - Shaun T. Cross
- Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States of America
- Cornell Institute of Host-Microbe Interactions and Disease, Cornell University, Ithaca, New York, United States of America
| | - Danica M. Sutherland
- Departments of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Olivia L. Welsh
- Departments of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Terence S. Dermody
- Departments of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- Departments of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- Institute of Infection, Inflammation, and Immunity, UPMC Children’s Hospital of Pittsburgh, Pennsylvania, United States of America
| | - John S. L. Parker
- Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, New York, United States of America
- Cornell Institute of Host-Microbe Interactions and Disease, Cornell University, Ithaca, New York, United States of America
- * E-mail:
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10
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Abstract
The function of the mammalian orthoreovirus (reovirus) σNS nonstructural protein is enigmatic. σNS is an RNA-binding protein that forms oligomers and enhances the stability of bound RNAs, but the mechanisms by which it contributes to reovirus replication are unknown. To determine the function of σNS-RNA binding in reovirus replication, we engineered σNS mutants deficient in RNA-binding capacity. We found that alanine substitutions of positively charged residues in a predicted RNA-binding domain decrease RNA-dependent oligomerization. To define steps in reovirus replication facilitated by the RNA-binding property of σNS, we established a complementation system in which wild-type or mutant forms of σNS could be tested for the capacity to overcome inhibition of σNS expression. Mutations in σNS that disrupt RNA binding also diminish viral replication and σNS distribution to viral factories. Moreover, viral mRNAs only incorporate into viral factories or factory-like structures (formed following expression of nonstructural protein μNS) when σNS is present and capable of binding RNA. Collectively, these findings indicate that σNS requires positively charged residues in a putative RNA-binding domain to recruit viral mRNAs to sites of viral replication and establish a function for σNS in reovirus replication.
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11
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The reovirus μ2 C-terminal loop inversely regulates NTPase and transcription functions versus binding to factory-forming μNS and promotes replication in tumorigenic cells. J Virol 2021; 95:JVI.02006-20. [PMID: 33658345 PMCID: PMC8139653 DOI: 10.1128/jvi.02006-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Wild type reovirus serotype 3 'Dearing PL strain' (T3wt) is being heavily evaluated as an oncolytic and immunotherapeutic treatment for cancers. Mutations that promote reovirus entry into tumor cells were previously reported to enhance oncolysis; herein we aimed to discover mutations that enhance the post-entry steps of reovirus infection in tumor cells. Using directed evolution, we identified that reovirus variant T3v10M1 exhibited enhanced replication relative to T3wt on a panel of cancer cells. T3v10M1 contains an alanine-to-valine substitution (A612V) in the core-associated μ2, which was previously found to have NTPase activities in virions and to facilitate virus factory formation by association with μNS. Paradoxically, the A612V mutation in μ2 from T3v10M1 was discovered to impair NTPase activities and RNA synthesis, leading to five-fold higher probability of abortive infection for T3v10M1 relative to T3wt. The A612V mutation resides in a previously uncharacterized C-terminal region that juxtaposes the template entry site of the polymerase μ2; our findings thus support an important role for this domain during virus transcription. Despite crippled onset of infection, T3v10M1 exhibited greater accumulation of viral proteins and progeny during replication, leading to increased overall virus burst size. Both Far-Western and co-immunoprecipitation approaches corroborated that the A612V mutation in μ2 increased association with the non-structural virus protein μNS and enhances burst size. Altogether the data supports that mutations in the C-terminal loop domain of μ2 inversely regulate NTPase and RNA synthesis versus interactions with μNS, but with a net gain of replication in tumorigenic cells.SIGNIFICANCEReovirus is a model system for understanding virus replication but also a clinically relevant virus for cancer therapy. We identified the first mutation that increases reovirus infection in tumorigenic cells by enhancing post-entry stages of reovirus replication. The mutation is in a previously uncharacterized c-terminal region of the M1-derived μ2 protein, which we demonstrated affects multiple functions of μ2; NTPase, RNA synthesis, inhibition of antiviral immune response and association with the virus replication factory-forming μNS protein. These findings promote a mechanistic understanding of viral protein functions. In the future, the benefits of μ2 mutations may be useful for enhancing reovirus potency in tumors.
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12
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Arnold MM, Dijk A, López S. Double‐stranded RNA Viruses. Virology 2021. [DOI: 10.1002/9781119818526.ch2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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13
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The Paradoxes of Viral mRNA Translation during Mammalian Orthoreovirus Infection. Viruses 2021; 13:v13020275. [PMID: 33670092 PMCID: PMC7916891 DOI: 10.3390/v13020275] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 02/08/2021] [Accepted: 02/09/2021] [Indexed: 02/06/2023] Open
Abstract
De novo viral protein synthesis following entry into host cells is essential for viral replication. As a consequence, viruses have evolved mechanisms to engage the host translational machinery while at the same time avoiding or counteracting host defenses that act to repress translation. Mammalian orthoreoviruses are dsRNA-containing viruses whose mRNAs were used as models for early investigations into the mechanisms that underpin the recognition and engagement of eukaryotic mRNAs by host cell ribosomes. However, there remain many unanswered questions and paradoxes regarding translation of reoviral mRNAs in the context of infection. This review summarizes the current state of knowledge about reovirus translation, identifies key unanswered questions, and proposes possible pathways toward a better understanding of reovirus translation.
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14
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Tenorio R, Fernández de Castro I, Knowlton JJ, Zamora PF, Sutherland DM, Risco C, Dermody TS. Function, Architecture, and Biogenesis of Reovirus Replication Neoorganelles. Viruses 2019; 11:v11030288. [PMID: 30901959 PMCID: PMC6466366 DOI: 10.3390/v11030288] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2019] [Revised: 03/17/2019] [Accepted: 03/19/2019] [Indexed: 02/06/2023] Open
Abstract
Most viruses that replicate in the cytoplasm of host cells form neoorganelles that serve as sites of viral genome replication and particle assembly. These highly specialized structures concentrate viral proteins and nucleic acids, prevent the activation of cell-intrinsic defenses, and coordinate the release of progeny particles. Reoviruses are common pathogens of mammals that have been linked to celiac disease and show promise for oncolytic applications. These viruses form nonenveloped, double-shelled virions that contain ten segments of double-stranded RNA. Replication organelles in reovirus-infected cells are nucleated by viral nonstructural proteins µNS and σNS. Both proteins partition the endoplasmic reticulum to form the matrix of these structures. The resultant membranous webs likely serve to anchor viral RNA⁻protein complexes for the replication of the reovirus genome and the assembly of progeny virions. Ongoing studies of reovirus replication organelles will advance our knowledge about the strategies used by viruses to commandeer host biosynthetic pathways and may expose new targets for therapeutic intervention against diverse families of pathogenic viruses.
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Affiliation(s)
- Raquel Tenorio
- Cell Structure Laboratory, National Center for Biotechnology, CNB-CSIC, Cantoblanco Campus, 28049 Madrid, Spain.
| | - Isabel Fernández de Castro
- Cell Structure Laboratory, National Center for Biotechnology, CNB-CSIC, Cantoblanco Campus, 28049 Madrid, Spain.
| | - Jonathan J Knowlton
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
| | - Paula F Zamora
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA.
| | - Danica M Sutherland
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA.
- Center for Microbial Pathogenesis, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA 15224, USA.
| | - Cristina Risco
- Cell Structure Laboratory, National Center for Biotechnology, CNB-CSIC, Cantoblanco Campus, 28049 Madrid, Spain.
| | - Terence S Dermody
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA.
- Department of Pediatrics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA.
- Center for Microbial Pathogenesis, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA 15224, USA.
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15
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Bourhill T, Mori Y, Rancourt DE, Shmulevitz M, Johnston RN. Going (Reo)Viral: Factors Promoting Successful Reoviral Oncolytic Infection. Viruses 2018; 10:E421. [PMID: 30103501 PMCID: PMC6116061 DOI: 10.3390/v10080421] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2018] [Revised: 08/09/2018] [Accepted: 08/09/2018] [Indexed: 02/06/2023] Open
Abstract
Oncolytic viruses show intriguing potential as cancer therapeutic agents. These viruses are capable of selectively targeting and killing cancerous cells while leaving healthy cells largely unaffected. The use of oncolytic viruses for cancer treatments in selected circumstances has recently been approved by the Food and Drug Administration (FDA) of the US and work is progressing on engineering viral vectors for enhanced selectivity, efficacy and safety. However, a better fundamental understanding of tumour and viral biology is essential for the continued advancement of the oncolytic field. This knowledge will not only help to engineer more potent and effective viruses but may also contribute to the identification of biomarkers that can determine which patients will benefit most from this treatment. A mechanistic understanding of the overlapping activity of viral and standard chemotherapeutics will enable the development of better combinational approaches to improve patient outcomes. In this review, we will examine each of the factors that contribute to productive viral infections in cancerous cells versus healthy cells. Special attention will be paid to reovirus as it is a well-studied virus and the only wild-type virus to have received orphan drug designation by the FDA. Although considerable insight into reoviral biology exists, there remain numerous deficiencies in our understanding of the factors regulating its successful oncolytic infection. Here we will discuss what is known to regulate infection as well as speculate about potential new mechanisms that may enhance successful replication. A joint appreciation of both tumour and viral biology will drive innovation for the next generation of reoviral mediated oncolytic therapy.
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Affiliation(s)
- Tarryn Bourhill
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada.
| | - Yoshinori Mori
- Department of Gastroenterology, Nagoya City West Medical Center, Kita-Ku, Nagoya 467-8601, Japan.
| | - Derrick E Rancourt
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada.
| | - Maya Shmulevitz
- Department of Medical Microbiology and Immunology, Li Ka Shing Institute of Virology, University of Alberta, Edmonton, AB T6G 2E1, Canada.
| | - Randal N Johnston
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, AB T2N 4N1, Canada.
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16
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Abstract
Like most viruses that replicate in the cytoplasm, mammalian reoviruses assemble membranous neo-organelles called inclusions that serve as sites of viral genome replication and particle morphogenesis. Viral inclusion formation is essential for viral infection, but how these organelles form is not well understood. We investigated the biogenesis of reovirus inclusions. Correlative light and electron microscopy showed that endoplasmic reticulum (ER) membranes are in contact with nascent inclusions, which form by collections of membranous tubules and vesicles as revealed by electron tomography. ER markers and newly synthesized viral RNA are detected in inclusion internal membranes. Live-cell imaging showed that early in infection, the ER is transformed into thin cisternae that fragment into small tubules and vesicles. We discovered that ER tubulation and vesiculation are mediated by the reovirus σNS and μNS proteins, respectively. Our results enhance an understanding of how viruses remodel cellular compartments to build functional replication organelles. Viruses modify cellular structures to build replication organelles. These organelles serve as sites of viral genome replication and particle morphogenesis and are essential for viral infection. However, how these organelles are constructed is not well understood. We found that the replication organelles of mammalian reoviruses are formed by collections of membranous tubules and vesicles derived from extensive remodeling of the peripheral endoplasmic reticulum (ER). We also observed that ER tubulation and vesiculation are triggered by the reovirus σNS and μNS proteins, respectively. Our results enhance an understanding of how viruses remodel cellular compartments to build functional replication organelles and provide functions for two enigmatic reovirus replication proteins. Most importantly, this research uncovers a new mechanism by which viruses form factories for particle assembly.
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