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Chen R, Wang SK, Belk JA, Amaya L, Li Z, Cardenas A, Abe BT, Chen CK, Wender PA, Chang HY. Engineering circular RNA for enhanced protein production. Nat Biotechnol 2023; 41:262-272. [PMID: 35851375 PMCID: PMC9931579 DOI: 10.1038/s41587-022-01393-0] [Citation(s) in RCA: 89] [Impact Index Per Article: 89.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 06/14/2022] [Indexed: 01/07/2023]
Abstract
Circular RNAs (circRNAs) are stable and prevalent RNAs in eukaryotic cells that arise from back-splicing. Synthetic circRNAs and some endogenous circRNAs can encode proteins, raising the promise of circRNA as a platform for gene expression. In this study, we developed a systematic approach for rapid assembly and testing of features that affect protein production from synthetic circRNAs. To maximize circRNA translation, we optimized five elements: vector topology, 5' and 3' untranslated regions, internal ribosome entry sites and synthetic aptamers recruiting translation initiation machinery. Together, these design principles improve circRNA protein yields by several hundred-fold, provide increased translation over messenger RNA in vitro, provide more durable translation in vivo and are generalizable across multiple transgenes.
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Affiliation(s)
- Robert Chen
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA, USA
| | - Sean K Wang
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA, USA
- Department of Ophthalmology, Stanford University School of Medicine, Stanford, CA, USA
| | - Julia A Belk
- Department of Computer Science, Stanford University, Stanford, CA, USA
| | - Laura Amaya
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA, USA
| | - Zhijian Li
- Department of Chemistry, Stanford University, Stanford, CA, USA
| | - Angel Cardenas
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA, USA
| | - Brian T Abe
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA, USA
| | - Chun-Kan Chen
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA, USA
| | - Paul A Wender
- Department of Chemistry, Stanford University, Stanford, CA, USA
- Department of Chemical and Systems Biology, Stanford University, Stanford, CA, USA
| | - Howard Y Chang
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA, USA.
- Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA.
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2
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Kim H, Aponte-Diaz D, Sotoudegan MS, Shengjuler D, Arnold JJ, Cameron CE. The enterovirus genome can be translated in an IRES-independent manner that requires the initiation factors eIF2A/eIF2D. PLoS Biol 2023; 21:e3001693. [PMID: 36689548 PMCID: PMC9894558 DOI: 10.1371/journal.pbio.3001693] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Revised: 02/02/2023] [Accepted: 01/04/2023] [Indexed: 01/24/2023] Open
Abstract
RNA recombination in positive-strand RNA viruses is a molecular-genetic process, which permits the greatest evolution of the genome and may be essential to stabilizing the genome from the deleterious consequences of accumulated mutations. Enteroviruses represent a useful system to elucidate the details of this process. On the biochemical level, it is known that RNA recombination is catalyzed by the viral RNA-dependent RNA polymerase using a template-switching mechanism. For this mechanism to function in cells, the recombining genomes must be located in the same subcellular compartment. How a viral genome is trafficked to the site of genome replication and recombination, which is membrane associated and isolated from the cytoplasm, is not known. We hypothesized that genome translation was essential for colocalization of genomes for recombination. We show that complete inactivation of internal ribosome entry site (IRES)-mediated translation of a donor enteroviral genome enhanced recombination instead of impairing it. Recombination did not occur by a nonreplicative mechanism. Rather, sufficient translation of the nonstructural region of the genome occurred to support subsequent steps required for recombination. The noncanonical translation initiation factors, eIF2A and eIF2D, were required for IRES-independent translation. Our results support an eIF2A/eIF2D-dependent mechanism under conditions in which the eIF2-dependent mechanism is inactive. Detection of an IRES-independent mechanism for translation of the enterovirus genome provides an explanation for a variety of debated observations, including nonreplicative recombination and persistence of enteroviral RNA lacking an IRES. The existence of an eIF2A/eIF2D-dependent mechanism in enteroviruses predicts the existence of similar mechanisms in other viruses.
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Affiliation(s)
- Hyejeong Kim
- Department of Microbiology and Immunology, School of Medicine, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - David Aponte-Diaz
- Department of Microbiology and Immunology, School of Medicine, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Mohamad S. Sotoudegan
- Department of Microbiology and Immunology, School of Medicine, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | | | - Jamie J. Arnold
- Department of Microbiology and Immunology, School of Medicine, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Craig E. Cameron
- Department of Microbiology and Immunology, School of Medicine, University of North Carolina, Chapel Hill, North Carolina, United States of America
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3
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Mahmud B, Horn CM, Tapprich WE. Structure of the 5' Untranslated Region of Enteroviral Genomic RNA. J Virol 2019; 93:e01288-19. [PMID: 31534036 PMCID: PMC6854513 DOI: 10.1128/jvi.01288-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 09/11/2019] [Indexed: 12/14/2022] Open
Abstract
Enteroviral RNA genomes share a long, highly structured 5' untranslated region (5' UTR) containing a type I internal ribosome entry site (IRES). The 5' UTR is composed of stably folded RNA domains connected by unstructured RNA regions. Proper folding and functioning of the 5' UTR underlies the efficiency of viral replication and also determines viral virulence. We have characterized the structure of 5' UTR genomic RNA from coxsackievirus B3 using selective 2'-hydroxyl acylation analyzed by primer extension (SHAPE) and base-specific chemical probes in solution. Our results revealed novel structural features, including realignment of major domains, newly identified long-range interactions, and an intrinsically disordered connecting region. Together, these newly identified features contribute to a model for enteroviral 5' UTRs with type I IRES elements that links structure to function during the hierarchical processes directed by genomic RNA during viral infection.IMPORTANCE Enterovirus infections are responsible for human diseases, including myocarditis, pancreatitis, acute flaccid paralysis, and poliomyelitis. The virulence of these viruses depends on efficient recognition of the RNA genome by a large family of host proteins and protein synthesis factors, which in turn relies on the three-dimensional folding of the first 750 nucleotides of the molecule. Structural information about this region of the genome, called the 5' untranslated region (5' UTR), is needed to assist in the process of vaccine and antiviral development. This work presents a model for the structure of the enteroviral 5' UTR. The model includes an RNA element called an intrinsically disordered RNA region (IDRR). Intrinsically disordered proteins (IDPs) are well known, but correlates in RNA have not been proposed. The proposed IDRR is a 20-nucleotide region, long known for its functional importance, where structural flexibility helps explain recognition by factors controlling multiple functional states.
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Affiliation(s)
- Bejan Mahmud
- Biology Department, University of Nebraska at Omaha, Omaha, Nebraska, USA
| | - Christopher M Horn
- Biology Department, University of Nebraska at Omaha, Omaha, Nebraska, USA
| | - William E Tapprich
- Biology Department, University of Nebraska at Omaha, Omaha, Nebraska, USA
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4
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Chang CK, Wu SR, Chen YC, Lee KJ, Chung NH, Lu YJ, Yu SL, Liu CC, Chow YH. Mutations in VP1 and 5'-UTR affect enterovirus 71 virulence. Sci Rep 2018; 8:6688. [PMID: 29703921 PMCID: PMC5923339 DOI: 10.1038/s41598-018-25091-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 04/16/2018] [Indexed: 11/27/2022] Open
Abstract
Enterovirus 71 (EV71) is a major cause of hand, foot and mouth disease (HFMD). The current EV71 propagating in Vero (EV-V) or sub-passaged in RD (EV-R) cells was used as a pathogen. Interestingly, EV-R exhibited differential virulence; challenging human scavenger receptor class B2-expressing (hSCARB2-Tg) mice with EV71 revealed that EV-V was more virulent than EV-R: 100% of mice that received lethal amounts of EV-V died, while all the mice that received EV-R survived. Severe pathogenesis correlated with viral burdens and proinflammatory cytokine levels were observed in EV-V-challenged mice, but controversy in EV-R-challenged mice. Consensus sequence analysis revealed EV-R rapidly acquired complete mutations at E145G and S241L and partial mutations at V146I of VP1, and acquired a T to C substitution at nucleotide 494 of the 5'-UTR. EV-R exhibited higher binding affinity for another EV71 receptor, human P-selectin glycoprotein ligand-1 (hPSGL-1), than EV-V. Both EV71s exhibited no significant difference in binding to hSCARB2. The molecular modelling indicate that these mutations might influence EV71 engagement with PSGL-1 and in vivo virulence.
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Affiliation(s)
- Ching-Kun Chang
- National Institute of Infectious Disease and Vaccinology, National Health Research Institutes, Zhunan, 350, Taiwan
- Graduate Institute of Life Science, National Defense Medical Center, Taipei, 114, Taiwan
| | - Shang-Rung Wu
- Institute of Oral Medicine, National Cheng Kung University, Tainan, 701, Taiwan
| | - Ying-Chin Chen
- National Institute of Infectious Disease and Vaccinology, National Health Research Institutes, Zhunan, 350, Taiwan
| | - Kuen-Jin Lee
- Institute of Oral Medicine, National Cheng Kung University, Tainan, 701, Taiwan
| | - Nai-Hsiang Chung
- National Institute of Infectious Disease and Vaccinology, National Health Research Institutes, Zhunan, 350, Taiwan
- Graduate Program of Biotechnology in Medicine, Institute of Molecular and Cellular Biology, National Tsing Hua University, Hsinchu, 300, Taiwan
| | - Yi-Ju Lu
- National Institute of Infectious Disease and Vaccinology, National Health Research Institutes, Zhunan, 350, Taiwan
| | - Shu-Ling Yu
- National Institute of Infectious Disease and Vaccinology, National Health Research Institutes, Zhunan, 350, Taiwan
- Graduate Institute of Life Science, National Defense Medical Center, Taipei, 114, Taiwan
| | - Chia-Chyi Liu
- National Institute of Infectious Disease and Vaccinology, National Health Research Institutes, Zhunan, 350, Taiwan
| | - Yen-Hung Chow
- National Institute of Infectious Disease and Vaccinology, National Health Research Institutes, Zhunan, 350, Taiwan.
- Graduate Institute of Life Science, National Defense Medical Center, Taipei, 114, Taiwan.
- Graduate Institute of Biomedical Sciences, China Medical University, Taichung, 404, Taiwan.
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5
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Tolbert M, Morgan CE, Pollum M, Crespo-Hernández CE, Li ML, Brewer G, Tolbert BS. HnRNP A1 Alters the Structure of a Conserved Enterovirus IRES Domain to Stimulate Viral Translation. J Mol Biol 2017; 429:2841-2858. [PMID: 28625847 PMCID: PMC5610934 DOI: 10.1016/j.jmb.2017.06.007] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Revised: 06/08/2017] [Accepted: 06/08/2017] [Indexed: 01/25/2023]
Abstract
Enteroviruses use a type I Internal Ribosome Entry Site (IRES) structure to facilitate protein synthesis and promote genome replication. Type I IRES elements require auxiliary host proteins to organize RNA structure for 40S ribosomal subunit assembly. Heterogeneous nuclear ribonucleoprotein A1 stimulates enterovirus 71 (EV71) translation in part through specific interactions with its stem loop II (SLII) IRES domain. Here, we determined a conjoined NMR-small angle x-ray scattering structure of the EV71 SLII domain and a mutant that significantly attenuates viral replication by abrogating hnRNP A1 interactions. Native SLII adopts a locally compact structure wherein stacking interactions in a conserved 5'-AUAGC-3' bulge preorganize the adjacent helices at nearly orthogonal orientations. Mutating the bulge sequence to 5'-ACCCC-3' ablates base stacking in the loop and globally reorients the SLII structure. Biophysical titrations reveal that the 5'-AUAGC-3' bulge undergoes a conformational change to assemble a functional hnRNP A1-RNA complex. Importantly, IRES mutations that delete the bulge impair viral translation and completely inhibit replication. Thus, this work provides key details into how an EV71 IRES structure adapts to hijack a cellular protein, and it suggests that the SLII domain is a potential target for antiviral therapy.
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Affiliation(s)
- Michele Tolbert
- Department of Chemistry, Case Western Reserve University, Cleveland, OH, 44106-7078 USA
| | - Christopher E Morgan
- Department of Chemistry, Case Western Reserve University, Cleveland, OH, 44106-7078 USA
| | - Marvin Pollum
- Department of Chemistry, Case Western Reserve University, Cleveland, OH, 44106-7078 USA
| | | | - Mei-Ling Li
- Department of Biochemistry and Molecular Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ, 08854 USA
| | - Gary Brewer
- Department of Biochemistry and Molecular Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ, 08854 USA
| | - Blanton S Tolbert
- Department of Chemistry, Case Western Reserve University, Cleveland, OH, 44106-7078 USA.
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6
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Li Z, Liu X, Wang S, Li J, Hou M, Liu G, Zhang W, Yu XF. Identification of a nucleotide in 5' untranslated region contributing to virus replication and virulence of Coxsackievirus A16. Sci Rep 2016; 6:20839. [PMID: 26861413 PMCID: PMC4748407 DOI: 10.1038/srep20839] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 01/13/2016] [Indexed: 12/18/2022] Open
Abstract
Coxsackievirus A16 (CA16) and enterovirus 71 (EV71) are two main causative pathogens of hand, foot and mouth disease (HFMD). Unlike EV71, virulence determinants of CA16, particularly within 5' untranslated region (5'UTR), have not been investigated until now. Here, a series of nucleotides present in 5'UTR of lethal but not in non-lethal CA16 strains were screened by aligning nucleotide sequences of lethal circulating Changchun CA16 and the prototype G10 as well as non-lethal SHZH05 strains. A representative infectious clone based on a lethal Changchun024 sequence and infectious mutants with various nucleotide alterations in 5'UTR were constructed and further investigated by assessing virus replication in vitro and virulence in neonatal mice. Compared to the lethal infectious clone, the M2 mutant with a change from cytosine to uracil at nucleotide 104 showed weaker virulence and lower replication capacity. The predicted secondary structure of the 5'UTR of CA16 RNA showed that M2 mutant located between the cloverleaf and stem-loop II, affected interactions between the 5'UTR and the heterogeneous nuclear ribonucleoprotein K (hnRNP K) and A1 (hnRNP A1) that are important for translational activity. Thus, our research determined a virulence-associated site in the 5'UTR of CA16, providing a crucial molecular target for antiviral drug development.
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Affiliation(s)
- Zhaolong Li
- First Hospital of Jilin University, Institute of Virology and AIDS Research, Changchun, Jilin Province, China.,College of Life Science, Jilin University, Changchun, Jilin Province, China
| | - Xin Liu
- First Hospital of Jilin University, Institute of Virology and AIDS Research, Changchun, Jilin Province, China
| | - Shaohua Wang
- First Hospital of Jilin University, Institute of Virology and AIDS Research, Changchun, Jilin Province, China
| | - Jingliang Li
- First Hospital of Jilin University, Institute of Virology and AIDS Research, Changchun, Jilin Province, China
| | - Min Hou
- First Hospital of Jilin University, Institute of Virology and AIDS Research, Changchun, Jilin Province, China
| | - Guanchen Liu
- First Hospital of Jilin University, Institute of Virology and AIDS Research, Changchun, Jilin Province, China.,College of Life Science, Jilin University, Changchun, Jilin Province, China
| | - Wenyan Zhang
- First Hospital of Jilin University, Institute of Virology and AIDS Research, Changchun, Jilin Province, China
| | - Xiao-Fang Yu
- First Hospital of Jilin University, Institute of Virology and AIDS Research, Changchun, Jilin Province, China
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7
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Muslin C, Joffret ML, Pelletier I, Blondel B, Delpeyroux F. Evolution and Emergence of Enteroviruses through Intra- and Inter-species Recombination: Plasticity and Phenotypic Impact of Modular Genetic Exchanges in the 5' Untranslated Region. PLoS Pathog 2015; 11:e1005266. [PMID: 26562151 PMCID: PMC4643034 DOI: 10.1371/journal.ppat.1005266] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 10/19/2015] [Indexed: 12/20/2022] Open
Abstract
Genetic recombination shapes the diversity of RNA viruses, including enteroviruses (EVs), which frequently have mosaic genomes. Pathogenic circulating vaccine-derived poliovirus (cVDPV) genomes consist of mutated vaccine poliovirus (PV) sequences encoding capsid proteins, and sequences encoding nonstructural proteins derived from other species’ C EVs, including certain coxsackieviruses A (CV-A) in particular. Many cVDPV genomes also have an exogenous 5’ untranslated region (5’ UTR). This region is involved in virulence and includes the cloverleaf (CL) and the internal ribosomal entry site, which play major roles in replication and the initiation of translation, respectively. We investigated the plasticity of the PV genome in terms of recombination in the 5’ UTR, by developing an experimental model involving the rescue of a bipartite PV/CV-A cVDPV genome rendered defective by mutations in the CL, following the co-transfection of cells with 5’ UTR RNAs from each of the four human EV species (EV-A to -D). The defective cVDPV was rescued by recombination with 5’ UTR sequences from the four EV species. Homologous and nonhomologous recombinants with large deletions or insertions in three hotspots were isolated, revealing a striking plasticity of the 5’ UTR. By contrast to the recombination of the cVDPV with the 5’ UTR of group II (EV-A and -B), which can decrease viral replication and virulence, recombination with the 5’ UTRs of group I (EV-C and -D) appeared to be evolutionarily neutral or associated with a gain in fitness. This study illustrates how the genomes of positive-strand RNA viruses can evolve into mosaic recombinant genomes through intra- or inter-species modular genetic exchanges, favoring the emergence of new recombinant lineages. Recombination shapes viral genomes, including those of the pathogenic circulating vaccine-derived polioviruses (cVDPVs), responsible for poliomyelitis outbreaks. The genomes of cVDPVs consist of sequences from vaccine poliovirus (PV) and other enteroviruses (EVs). We investigated the plasticity of cVDPV genomes and the effects of recombination in the 5’ untranslated region (5’ UTR), which is involved in replication, translation and virulence. We rescued a 5’ UTR-defective recombinant cVDPV genome by cotransfecting cells with 5’ UTR RNAs from human EV species EV-A to -D. Hundreds of recombinants were isolated, revealing striking plasticity in this region, with homologous and nonhomologous recombination sites mostly clustered in three hotspots. Recombination with EV-A and -B affected replication and virulence, whereas recombination with EV-C and -D was either neutral or improved viral fitness. This study illustrates how RNA viruses can acquire mosaic genomes through intra- or inter-species recombination, favoring the emergence of new recombinant strains.
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Affiliation(s)
- Claire Muslin
- Institut Pasteur, Biologie des Virus Entériques, Paris, France
- INSERM U994, Institut National de Santé et de La Recherche Médicale, Paris, France
- Université Paris Diderot, Sorbonne Paris Cité, Cellule Pasteur, Paris, France
| | - Marie-Line Joffret
- Institut Pasteur, Biologie des Virus Entériques, Paris, France
- INSERM U994, Institut National de Santé et de La Recherche Médicale, Paris, France
| | - Isabelle Pelletier
- Institut Pasteur, Biologie des Virus Entériques, Paris, France
- INSERM U994, Institut National de Santé et de La Recherche Médicale, Paris, France
| | - Bruno Blondel
- Institut Pasteur, Biologie des Virus Entériques, Paris, France
- INSERM U994, Institut National de Santé et de La Recherche Médicale, Paris, France
| | - Francis Delpeyroux
- Institut Pasteur, Biologie des Virus Entériques, Paris, France
- INSERM U994, Institut National de Santé et de La Recherche Médicale, Paris, France
- * E-mail:
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8
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Mutational Disruption of cis-Acting Replication Element 2C in Coxsackievirus B3 Leads to 5'-Terminal Genomic Deletions. J Virol 2015; 89:11761-72. [PMID: 26355088 PMCID: PMC4645312 DOI: 10.1128/jvi.01308-15] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 09/01/2015] [Indexed: 12/14/2022] Open
Abstract
UNLABELLED Following natural human or experimental murine infections and in cell culture, coxsackievirus B (CVB) RNA can persist for weeks in the absence of a cytopathic effect, yet viral RNA remains detectable. Our earlier studies demonstrated that this persistence produced viral RNA with up to 49 nucleotide deletions at the genomic 5' terminus which partially degraded the cloverleaf (or domain I), an RNA structure required for efficient viral replication. A cis-acting replication element (CRE) in the 2C protein-coding region [CRE(2C)] templates the addition of two uridine residues to the virus genome-encoded RNA replication primer VPg prior to positive-strand synthesis. Because our previous work also demonstrated that the genomes of CVB with a 5'-terminal deletion (CVB-TD) have VPg covalently linked, even though they rarely terminate in the canonical UU donated by CRE(2C)-mediated uridylylation of VPg, we hypothesized that a functional (uridylylating) CRE(2C) would be unnecessary for CVB-TD replication. Using the same 16 mutations in the CVB3 CRE(2C) structure that were considered lethal for this virus by others, we demonstrate here both in infected cell cultures and in mice that wild-type (wt) and CVB3-TD strains carrying these mutations with a nonuridylylating CRE(2C) are viable. While the wt genome with the mutated CRE(2C) displays suppressed replication levels similar to those observed in a CVB3-TD strain, mutation of the CRE(2C) function in a CVB3-TD strain does not further decrease replication. Finally, we show that replication of the parental CVB3 strain containing the mutated CRE(2C) drives the de novo generation of genomic deletions at the 5' terminus. IMPORTANCE In this report, we demonstrate that while CVB can replicate without a uridylylating CRE(2C), the replication rate suffers significantly. Further, deletions at the 5' terminus of the genome are generated in this virus population, with this virus population supplanting the wild-type population. This demonstrates that VPg can prime without being specifically uridylylated and that this priming is error prone, resulting in the loss of sequence information from the 5' terminus. These findings have significance when considering the replication of human enteroviruses, and we believe that these data are unattainable in a cell-free system due to the poor replication of these CRE-deficient viruses.
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9
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Prusa J, Missak J, Kittrell J, Evans JJ, Tapprich WE. Major alteration in coxsackievirus B3 genomic RNA structure distinguishes a virulent strain from an avirulent strain. Nucleic Acids Res 2014; 42:10112-21. [PMID: 25074382 PMCID: PMC4150801 DOI: 10.1093/nar/gku706] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Coxsackievirus B3 (CV-B3) is a cardiovirulent enterovirus that utilizes a 5′ untranslated region (5′UTR) to complete critical viral processes. Here, we directly compared the structure of a 5′UTR from a virulent strain with that of a naturally occurring avirulent strain. Using chemical probing analysis, we identified a structural difference between the two 5′UTRs in the highly substituted stem-loop II region (SLII). For the remainder of the 5′UTR, we observed conserved structure. Comparative sequence analysis of 170 closely related enteroviruses revealed that the SLII region lacks conservation. To investigate independent folding and function, two chimeric CV-B3 strains were created by exchanging nucleotides 104–184 and repeating the 5′UTR structural analysis. Neither the parent SLII nor the remaining domains of the background 5′UTR were structurally altered by the exchange, supporting an independent mechanism of folding and function. We show that the attenuated 5′UTR lacks structure in the SLII cardiovirulence determinant.
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Affiliation(s)
- Jerome Prusa
- Biology Department, University of Nebraska at Omaha, Omaha, NE 68182, USA
| | - Johanna Missak
- Department of Family Medicine, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Jeff Kittrell
- Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - John J Evans
- Department of Pathology, University of Colorado Anshutz Medical Campus, Denver, CO 80045, USA
| | - William E Tapprich
- Biology Department, University of Nebraska at Omaha, Omaha, NE 68182, USA
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10
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Zhou F, Wang Q, Sintchenko V, Gilbert GL, O'Sullivan MVN, Iredell JR, Dwyer DE. Use of the 5' untranslated region and VP1 region to examine the molecular diversity in enterovirus B species. J Med Microbiol 2014; 63:1339-1355. [PMID: 25038138 DOI: 10.1099/jmm.0.074682-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Human enteroviruses evolve quickly. The 5' untranslated region (UTR) is fundamentally important for efficient viral replication and for virulence; the VP1 region correlates well with antigenic typing by neutralization, and can be used for virus identification and evolutionary studies. In order to investigate the molecular diversity in EV-B species, the 5' UTR and VP1 regions were analysed for 208 clinical isolates from a single public-health laboratory (serving New South Wales, Australia), representing 28 EV-B types. Sequences were compared with the 5' UTR and VP1 regions of 98 strains available in GenBank, representing the same 28 types. The genetic relationships were analysed using two types of software (mega and BioNumerics). The sequence analyses of the 5' UTR and VP1 regions of 306 EV-B strains demonstrated that: (i) comparing the two regions gives strong evidence of epidemiological linkage of strains in some serotypes; (ii) the intraserotypic genetic variation within each gene reveals that they evolve distinctly largely due to their different functions; and (iii) mutation and possible recombination in the two regions play significant roles in the molecular diversity of EV-B. Understanding the tempo and pattern of molecular diversity and evolution is of great importance in the pathogenesis of EV-B enteroviruses, information which will assist in disease prevention and control.
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Affiliation(s)
- Fei Zhou
- Centre for Infectious Diseases and Microbiology (CIDM), Institute of Clinical Pathology and Medical Research (ICPMR), Westmead Hospital, University of Sydney, Westmead, New South Wales, Australia
| | - Qinning Wang
- Centre for Infectious Diseases and Microbiology (CIDM), Institute of Clinical Pathology and Medical Research (ICPMR), Westmead Hospital, University of Sydney, Westmead, New South Wales, Australia
| | - Vitali Sintchenko
- Centre for Infectious Diseases and Microbiology (CIDM), Institute of Clinical Pathology and Medical Research (ICPMR), Westmead Hospital, University of Sydney, Westmead, New South Wales, Australia
| | - Gwendolyn L Gilbert
- Centre for Infectious Diseases and Microbiology (CIDM), Institute of Clinical Pathology and Medical Research (ICPMR), Westmead Hospital, University of Sydney, Westmead, New South Wales, Australia
| | - Matthew V N O'Sullivan
- Centre for Infectious Diseases and Microbiology (CIDM), Institute of Clinical Pathology and Medical Research (ICPMR), Westmead Hospital, University of Sydney, Westmead, New South Wales, Australia
| | - Jonathan R Iredell
- Centre for Infectious Diseases and Microbiology (CIDM), Institute of Clinical Pathology and Medical Research (ICPMR), Westmead Hospital, University of Sydney, Westmead, New South Wales, Australia
| | - Dominic E Dwyer
- Centre for Infectious Diseases and Microbiology (CIDM), Institute of Clinical Pathology and Medical Research (ICPMR), Westmead Hospital, University of Sydney, Westmead, New South Wales, Australia
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11
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Souii A, Ben M'hadheb-Gharbi M, Gharbi J. Role of RNA structure motifs in IRES-dependent translation initiation of the coxsackievirus B3: new insights for developing live-attenuated strains for vaccines and gene therapy. Mol Biotechnol 2014; 55:179-202. [PMID: 23881360 DOI: 10.1007/s12033-013-9674-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Internal ribosome entry site (IRES) elements are highly structured RNA sequences that function to recruit ribosomes for the initiation of translation. In contrast to the canonical cap-binding, the mechanism of IRES-mediated translation initiation is still poorly understood. Translation initiation of the coxsackievirus B3 (CVB3), a causative agent of viral myocarditis, has been shown to be mediated by a highly ordered structure of the 5' untranslated region (5'UTR), which harbors an IRES. Taking into account that efficient initiation of mRNA translation depends on temporally and spatially orchestrated sequence of RNA-protein and RNA-RNA interactions, and that, at present, little is known about these interactions, we aimed to describe recent advances in our understanding of molecular structures and biochemical functions of the translation initiation process. Thus, this review will explore the IRES elements as important RNA structures and the significance of these structures in providing an alternative mechanism of translation initiation of the CVB3 RNA. Since translation initiation is the first intracellular step during the CVB3 infection cycle, the IRES region provides an ideal target for antiviral therapies. Interestingly, the 5' and 3'UTRs represent promising candidates for the study of CVB3 cardiovirulence and provide new insights for developing live-attenuated vaccines.
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Affiliation(s)
- Amira Souii
- Institut Supérieur de Biotechnologie de Monastir-Université de Monastir, Avenue Tahar Hadded, BP 74, 5000, Monastir, Tunisia
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12
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Jin M, Zhao ZG, Wang XW, Shen ZQ, Xu L, Yu YM, Qiu ZG, Chen ZL, Wang JF, Huang AH, Li JW. The 40-80 nt region in the 5'-NCR of genome is a critical target for inactivating poliovirus by chlorine dioxide. J Med Virol 2012; 84:526-35. [PMID: 22246842 DOI: 10.1002/jmv.23221] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Chemical disinfection is the most common method used to inactivate viruses from drinking water throughout the world. In this study, cell culture, ELISA, RT-PCR, and spot hybridization were employed to investigate the mechanism underlying chlorine dioxide (ClO(2) )-induced inactivation of Poliovirus type 1 (PV1), which was also confirmed by recombinant viral genome RNA infection models. The results suggested that ClO(2) inactivated PV1 primarily by disrupting the 5'-non-coding region (5'-NCR) of the PV1 genome. Further study revealed that ClO(2) degraded specifically the 40-80 nucleotides (nt) region in the 5'-NCR. Recombinant viral genome RNA infection models confirmed that PV1 RNA lacking this 40-80 nt region was not infectious. This study not only elucidated the mechanism of PV1 inactivation by ClO(2), but also defined the critical genetic target for the disinfectant to inactivate Poliovirus. This study also provides a strategy by which rapid, accurate, and molecular methods based on sensitive genetic targets may be established for evaluating the effects of disinfectants on viruses.
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Affiliation(s)
- Min Jin
- Department of Environment and Health, Institute of Health and Environmental Medicine, Key Laboratory of Risk Assessment and Control for Environment and Food Safety, Tianjin, China
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13
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Kaempferol inhibits enterovirus 71 replication and internal ribosome entry site (IRES) activity through FUBP and HNRP proteins. Food Chem 2011; 128:312-22. [DOI: 10.1016/j.foodchem.2011.03.022] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Revised: 01/05/2011] [Accepted: 03/04/2011] [Indexed: 02/02/2023]
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14
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Altered interactions between stem-loop IV within the 5' noncoding region of coxsackievirus RNA and poly(rC) binding protein 2: effects on IRES-mediated translation and viral infectivity. Virology 2009; 389:45-58. [PMID: 19446305 DOI: 10.1016/j.virol.2009.03.012] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2008] [Revised: 01/30/2009] [Accepted: 03/05/2009] [Indexed: 11/24/2022]
Abstract
Coxsackievirus B3 (CVB3) is a causative agent of viral myocarditis, meningitis, pancreatitis, and encephalitis. Much of what is known about the coxsackievirus intracellular replication cycle is based on the information already known from a well-studied and closely related virus, poliovirus. Like that of poliovirus, the 5' noncoding region (5' NCR) of CVB3 genomic RNA contains secondary structures that function in both viral RNA replication and cap-independent translation initiation. For poliovirus IRES-mediated translation, the interaction of the cellular protein PCBP2 with a major secondary structure element (stem-loop IV) is required for gene expression. Previously, the complete secondary structure of the coxsackievirus 5' NCR was determined by chemical structure probing and overall, many of the RNA secondary structures bear significant similarity to those of poliovirus; however, the functions of the coxsackievirus IRES stem-loop structures have not been determined. Here we report that a CVB3 RNA secondary structure, stem-loop IV, folds similarly to poliovirus stem-loop IV and like its enterovirus counterpart, coxsackievirus stem-loop IV interacts with PCBP2. We used RNase foot-printing to identify RNA sequences protected following PCBP2 binding to coxsackievirus stem-loop IV. When nucleotide substitutions were separately engineered at two sites in coxsackievirus stem-loop IV to reduce PCBP2 binding, inhibition of IRES-mediated translation was observed. Both of these nucleotide substitutions were engineered into full-length CVB3 RNA and upon transfection into HeLa cells, the specific infectivities of both constructs were reduced and the recovered viruses displayed small-plaque phenotypes and slower growth kinetics compared to wild type virus.
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15
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Steil BP, Barton DJ. Cis-active RNA elements (CREs) and picornavirus RNA replication. Virus Res 2008; 139:240-52. [PMID: 18773930 DOI: 10.1016/j.virusres.2008.07.027] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2008] [Revised: 07/25/2008] [Accepted: 07/29/2008] [Indexed: 10/21/2022]
Abstract
Our understanding of picornavirus RNA replication has improved over the past 10 years, due in large part to the discovery of cis-active RNA elements (CREs) within picornavirus RNA genomes. CREs function as templates for the conversion of VPg, the Viral Protein of the genome, into VPgpUpU(OH). These so called CREs are different from the previously recognized cis-active RNA sequences and structures within the 5' and 3' NTRs of picornavirus genomes. Two adenosine residues in the loop of the CRE RNA structures allow the viral RNA-dependent RNA polymerase 3D(Pol) to add two uridine residues to the tyrosine residue of VPg. Because VPg and/or VPgpUpU(OH) prime the initiation of viral RNA replication, the asymmetric replication of viral RNA could not be explained without an understanding of the viral RNA template involved in the conversion of VPg into VPgpUpU(OH) primers. We review the growing body of knowledge regarding picornavirus CREs and discuss how CRE RNAs work coordinately with viral replication proteins and other cis-active RNAs in the 5' and 3' NTRs during RNA replication.
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Affiliation(s)
- Benjamin P Steil
- Department of Microbiology and Program in Molecular Biology, University of Colorado Denver, School of Medicine, United States
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16
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Poliovirus cis-acting replication element-dependent VPg Uridylylation lowers the Km of the initiating nucleoside triphosphate for viral RNA replication. J Virol 2008; 82:9400-8. [PMID: 18653453 DOI: 10.1128/jvi.00427-08] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Initiation of RNA synthesis by RNA-dependent RNA polymerases occurs when a phosphodiester bond is formed between the first two nucleotides in the 5' terminus of product RNA. The concentration of initiating nucleoside triphosphates (NTPi) required for RNA synthesis is typically greater than the concentration of NTPs required for elongation. VPg, a small viral protein, is covalently attached to the 5' end of picornavirus negative- and positive-strand RNAs. A cis-acting replication element (CRE) within picornavirus RNAs serves as a template for the uridylylation of VPg, resulting in the synthesis of VPgpUpU(OH). Mutations within the CRE RNA structure prevent VPg uridylylation. While the tyrosine hydroxyl of VPg can prime negative-strand RNA synthesis in a CRE- and VPgpUpU(OH)-independent manner, CRE-dependent VPgpUpU(OH) synthesis is absolutely required for positive-strand RNA synthesis. As reported herein, low concentrations of UTP did not support negative-strand RNA synthesis when CRE-disrupting mutations prevented VPg uridylylation, whereas correspondingly low concentrations of CTP or GTP had no negative effects on the magnitude of CRE-independent negative-strand RNA synthesis. The experimental data indicate that CRE-dependent VPg uridylylation lowers the K(m) of UTP required for viral RNA replication and that CRE-dependent VPgpUpU(OH) synthesis was required for efficient negative-strand RNA synthesis, especially when UTP concentrations were limiting. By lowering the concentration of UTP needed for the initiation of RNA replication, CRE-dependent VPg uridylylation provides a mechanism for a more robust initiation of RNA replication.
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17
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Poly(rC) binding proteins and the 5' cloverleaf of uncapped poliovirus mRNA function during de novo assembly of polysomes. J Virol 2008; 82:5835-46. [PMID: 18400854 DOI: 10.1128/jvi.01513-07] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Poliovirus (PV) mRNA is unusual because it possesses a 5'-terminal monophosphate rather than a 5'-terminal cap. Uncapped mRNAs are typically degraded by the 5' exonuclease XRN1. A 5'-terminal cloverleaf RNA structure interacts with poly(rC) binding proteins (PCBPs) to protect uncapped PV mRNA from 5' exonuclease (K. E. Murray, A. W. Roberts, and D. J. Barton, RNA 7:1126-1141, 2001). In this study, we examined de novo polysome formation using HeLa cell-free translation-replication reactions. PV mRNA formed polysomes coordinate with the time needed for ribosomes to traverse the viral open reading frame (ORF). Nascent PV polypeptides cofractionated with viral polysomes, while mature PV proteins were released from the polysomes. Alterations in the size of the PV ORF correlated with alterations in the size of polysomes with ribosomes present every 250 to 500 nucleotides of the ORF. Eukaryotic initiation factor 4GI (eIF4GI) was cleaved rapidly as viral polysomes assembled and the COOH-terminal portion of eIF4GI cofractionated with viral polysomes. Poly(A) binding protein, along with PCBP 1 and 2, also cofractionated with viral polysomes. A C24A mutation that inhibits PCBP-5'-terminal cloverleaf RNA interactions inhibited the formation and stability of nascent PV polysomes. Kinetic analyses indicated that the PCBP-5' cloverleaf RNA interaction was necessary to protect PV mRNA from 5' exonuclease immediately as ribosomes initially traversed the viral ORF, before viral proteins could alter translation factors within nascent polysomes or contribute to ribonucleoprotein complexes at the termini of the viral mRNA.
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18
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Chapman NM, Kim KS, Drescher KM, Oka K, Tracy S. 5' terminal deletions in the genome of a coxsackievirus B2 strain occurred naturally in human heart. Virology 2008; 375:480-91. [PMID: 18378272 DOI: 10.1016/j.virol.2008.02.030] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Revised: 12/19/2007] [Accepted: 02/21/2008] [Indexed: 01/17/2023]
Abstract
Enteroviruses can induce human myocarditis, which can be modeled in mice inoculated with group B coxsackieviruses (CVB) and in which CVB evolve to produce defective, terminally deleted genomes. The 5' non-translated region (NTR) was enzymatically amplified from heart tissue of a fatal case of enterovirus-associated myocarditis in Japan in 2002. While no intact 5' viral genomic termini were detected, 5' terminal deletions ranged in size from 22 to 36 nucleotides. Sequence of the 5' third of this viral genome is of a modern strain, closely related to CVB2 strains isolated in Japan in 2002. A CVB3 chimera containing the 5' NTR with a 22 nt deletion produced progeny virus upon transfection of HeLa cells. When the 5' 22 nucleotide deletion was repaired, the virus induced myocarditis in mice and replicated like wild type virus in murine heart cells. This is the first report of these naturally-occurring defective enteroviral genomes in human myocarditis.
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Affiliation(s)
- Nora M Chapman
- Enterovirus Research Laboratory, Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198-6495, USA.
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19
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Hu B, Pillai-Nair N, Hemenway C. Long-distance RNA-RNA interactions between terminal elements and the same subset of internal elements on the potato virus X genome mediate minus- and plus-strand RNA synthesis. RNA (NEW YORK, N.Y.) 2007; 13:267-80. [PMID: 17185361 PMCID: PMC1781375 DOI: 10.1261/rna.243607] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Potexvirus genomes contain conserved terminal elements that are complementary to multiple internal octanucleotide elements. Both local sequences and structures at the 5' terminus and long-distance interactions between this region and internal elements are important for accumulation of potato virus X (PVX) plus-strand RNA in vivo. In this study, the role of the conserved hexanucleotide motif within SL3 of the 3' NTR and internal conserved octanucleotide elements in minus-strand RNA synthesis was analyzed using both a template-dependent, PVX RNA-dependent RNA polymerase (RdRp) extract and a protoplast replication system. Template analyses in vitro indicated that 3' terminal templates of 850 nucleotides (nt), but not 200 nt, supported efficient, minus-strand RNA synthesis. Mutational analyses of the longer templates indicated that optimal transcription requires the hexanucleotide motif in SL3 within the 3' NTR and the complementary CP octanucleotide element 747 nt upstream. Additional experiments to disrupt interactions between one or more internal conserved elements and the 3' hexanucleotide element showed that long-distance interactions were necessary for minus-strand RNA synthesis both in vitro and in vivo. Additionally, multiple internal octanucleotide elements could serve as pairing partners with the hexanucleotide element in vivo. These cis-acting elements and interactions correlate in several ways to those previously observed for plus-strand RNA accumulation in vivo, suggesting that dynamic interactions between elements at both termini and the same subset of internal octanucleotide elements are required for both minus- and plus-strand RNA synthesis and potentially other aspects of PVX replication.
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Affiliation(s)
- Bin Hu
- Department of Molecular and Structural Biochemistry, North Carolina State University, Raleigh 27695-7622, USA
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20
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Zhang YD, Lu XL, Li NF. The prospective preventative HIV vaccine based on modified poliovirus. Med Hypotheses 2007; 68:1258-61. [PMID: 17196342 DOI: 10.1016/j.mehy.2006.07.062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2006] [Accepted: 07/18/2006] [Indexed: 09/30/2022]
Abstract
In order to control HIV pandemic, many vaccines are invented. Although none first verified its efficacy in clinic, we hypothesize that HIV vaccine based on poliovirus is potential to develop the promising one, because it can elicit the broad immune response including the main mucosal, humoral and cellular reaction. However, the viral neural virulence is one major concern. The attenuated Sabin strain is a better candidate. While partial poliovirus genes are replaced by HIV antigen genes, the defective interfering particle will fail to produce progeny virions, which may further ensure its security. Although the vaccinal immune efficacy was verified in some similar animal experiments based on poliovirus to express the exogenous genes, more animal and clinical immune trials about HIV-poliovirus chimeric minireplicons are to be carried out and the hypotheses are to be validated.
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Affiliation(s)
- Yang-de Zhang
- Institute of Biomedical Engineering, Central South University, Xiangya Road, Kai-Fu District, Changsha, Hunan 410008, PR China.
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21
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Bailey JM, Tapprich WE. Structure of the 5' nontranslated region of the coxsackievirus b3 genome: Chemical modification and comparative sequence analysis. J Virol 2006; 81:650-68. [PMID: 17079314 PMCID: PMC1797431 DOI: 10.1128/jvi.01327-06] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Coxsackievirus B3 (CVB3) is a picornavirus which causes myocarditis and pancreatitis and may play a role in type I diabetes. The viral genome is a single 7,400-nucleotide polyadenylated RNA encoding 11 proteins in a single open reading frame. The 5' end of the viral genome contains a highly structured nontranslated region (5'NTR) which folds to form an internal ribosome entry site (IRES) as well as structures responsible for genome replication, both of which are critical for virulence. A structural model of the CVB3 5'NTR, generated primarily by comparative sequence analysis and energy minimization, shows seven domains (I to VII). While this model provides a preliminary basis for structural analysis, the model lacks comprehensive experimental validation. Here we provide experimental evidence from chemical modification analysis to determine the structure of the CVB3 5'NTR. Chemical probing results show that the theoretical model for the CVB3 5'NTR is largely, but not completely, supported experimentally. In combination with our chemical probing data, we have used the RNASTRUCTURE algorithm and sequence comparison of 105 enterovirus sequences to provide evidence for novel secondary and tertiary interactions. A comprehensive examination of secondary structure is discussed, along with new evidence for tertiary interactions. These include a loop E motif in domain III and a long-range pairing interaction that links domain II to domain V. The results of our work provide mechanistic insight into key functional elements in the cloverleaf and IRES, thereby establishing a base of structural information from which to interpret experiments with CVB3 and other picornaviruses.
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Affiliation(s)
- Jennifer M Bailey
- Department of Biology, University of Nebraska at Omaha, 6001 Dodge St, Omaha, NE 68182, USA
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22
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Campbell SA, Lin J, Dobrikova EY, Gromeier M. Genetic determinants of cell type-specific poliovirus propagation in HEK 293 cells. J Virol 2005; 79:6281-90. [PMID: 15858012 PMCID: PMC1091735 DOI: 10.1128/jvi.79.10.6281-6290.2005] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The ability of poliovirus to propagate in neuronal cells can be reduced by introducing appropriate nucleotide substitutions into the viral genome. Specific mutations scattered throughout the poliovirus genome yielded the live attenuated vaccine strains of poliovirus. Neuron-specific propagation deficits of the Sabin strains are partially encrypted within a confined region of the internal ribosomal entry site (IRES), which carries attenuating point mutations in all three serotypes. Recently, high levels of neurovirulence attenuation were achieved with genetically engineered polioviruses containing heterologous IRES elements. This is exemplified with poliovirus recombinants replicating under control of a human rhinovirus type 2 (HRV2) IRES element. We have carried out experiments delineating the genetic basis for neuronal IRES function. Neuronal dysfunction of the HRV2 IRES is determined mainly by IRES stem-loop domain V, the locus for attenuating point mutations within the Sabin strains. Neuronal incompetence associated with HRV2 IRES domain V is substantially more pronounced than that observed with the attenuating IRES point mutation of the Sabin serotype 1 vaccine strain. Mix-and-match recombination of polio and HRV2 IRES domain V suggests that the attenuation phenotype correlates with overall structural features rather than primary sequence. Our experiments have identified HEK 293 cells as a novel system for the study of neuron-specific replication phenotypes of poliovirus. This cell line, originally derived from embryonic human kidney, has recently been described to display neuronal characteristics. We report propagation properties in HEK 293 cells for poliovirus recombinants with attenuated neurovirulence in experimental animals that corroborate this observation.
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Affiliation(s)
- Stephanie A Campbell
- Dept. of Molecular Genetics and Microbiology, Duke University Medical Center, Box 3020, Durham, NC 27710, USA
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23
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Kim KS, Tracy S, Tapprich W, Bailey J, Lee CK, Kim K, Barry WH, Chapman NM. 5'-Terminal deletions occur in coxsackievirus B3 during replication in murine hearts and cardiac myocyte cultures and correlate with encapsidation of negative-strand viral RNA. J Virol 2005; 79:7024-41. [PMID: 15890942 PMCID: PMC1112132 DOI: 10.1128/jvi.79.11.7024-7041.2005] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Adult human enteroviral heart disease is often associated with the detection of enteroviral RNA in cardiac muscle tissue in the absence of infectious virus. Passage of coxsackievirus B3 (CVB3) in adult murine cardiomyocytes produced CVB3 that was noncytolytic in HeLa cells. Detectable but noncytopathic CVB3 was also isolated from hearts of mice inoculated with CVB3. Sequence analysis revealed five classes of CVB3 genomes with 5' termini containing 7, 12, 17, 30, and 49 nucleotide deletions. Structural changes (assayed by chemical modification) in cloned, terminally deleted 5'-nontranslated regions were confined to the cloverleaf domain and localized within the region of the deletion, leaving key functional elements of the RNA intact. Transfection of CVB3 cDNA clones with the 5'-terminal deletions into HeLa cells generated noncytolytic virus (CVB3/TD) which was neutralized by anti-CVB3 serum. Encapsidated negative-strand viral RNA was detected using CsCl-purified CVB3/TD virions, although no negative-strand virion RNA was detected in similarly treated parental CVB3 virions. The viral protein VPg was detected on CVB3/TD virion RNA molecules which terminate in 5' CG or 5' AG. Detection of viral RNA in mouse hearts from 1 week to over 5 months postinoculation with CVB3/TD demonstrated that CVB3/TD virus strains replicate and persist in vivo. These studies describe a naturally occurring genomic alteration to an enteroviral genome associated with long-term viral persistence.
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MESH Headings
- Animals
- Base Sequence
- Cells, Cultured
- Cytopathogenic Effect, Viral
- DNA, Viral/genetics
- Enterovirus B, Human/genetics
- Enterovirus B, Human/pathogenicity
- Enterovirus B, Human/physiology
- Enterovirus Infections/virology
- Genome, Viral
- HeLa Cells
- Humans
- Male
- Mice
- Mice, Inbred A
- Molecular Sequence Data
- Myocarditis/virology
- Myocytes, Cardiac/virology
- Nucleic Acid Conformation
- RNA, Viral/chemistry
- RNA, Viral/genetics
- RNA, Viral/metabolism
- Sequence Deletion
- Virus Assembly
- Virus Replication
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Affiliation(s)
- K-S Kim
- Enterovirus Research Laboratory, Department of Pathology and Microbiology, University of Nebraska Medical Center, 986495 Nebraska Medical Center, Omaha, NE 68198-6495, USA
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24
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Nagashima S, Sasaki J, Taniguchi K. The 5'-terminal region of the Aichi virus genome encodes cis-acting replication elements required for positive- and negative-strand RNA synthesis. J Virol 2005; 79:6918-31. [PMID: 15890931 PMCID: PMC1112095 DOI: 10.1128/jvi.79.11.6918-6931.2005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Aichi virus is a member of the family Picornaviridae. It has already been shown that three stem-loop structures (SL-A, SL-B, and SL-C, from the 5' end) formed at the 5' end of the genome are critical elements for viral RNA replication. In this study, we further characterized the 5'-terminal cis-acting replication elements. We found that an additional structural element, a pseudoknot structure, is formed through base-pairing interaction between the loop segment of SL-B (nucleotides [nt] 57 to 60) and a sequence downstream of SL-C (nt 112 to 115) and showed that the formation of this pseudoknot is critical for viral RNA replication. Mapping of the 5'-terminal sequence of the Aichi virus genome required for RNA replication using a series of Aichi virus-encephalomyocarditis virus chimera replicons indicated that the 5'-end 115 nucleotides including the pseudoknot structure are the minimum requirement for RNA replication. Using the cell-free translation-replication system, we examined the abilities of viral RNAs with a lethal mutation in the 5'-terminal structural elements to synthesize negative- and positive-strand RNAs. The results showed that the formation of three stem-loops and the pseudoknot structure at the 5' end of the genome is required for negative-strand RNA synthesis. In addition, specific nucleotide sequences in the stem of SL-A or its complementary sequences at the 3' end of the negative-strand were shown to be critical for the initiation of positive-strand RNA synthesis but not for that of negative-strand synthesis. Thus, the 5' end of the Aichi virus genome encodes elements important for not only negative-strand synthesis but also positive-strand synthesis.
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Affiliation(s)
- Shigeo Nagashima
- Department of Virology and Parasitology, Fujita Health University School of Medicine, Toyoake, Aichi 470-1192, Japan
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25
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Egger D, Bienz K. Intracellular location and translocation of silent and active poliovirus replication complexes. J Gen Virol 2005; 86:707-718. [PMID: 15722531 DOI: 10.1099/vir.0.80442-0] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Replication of poliovirus (PV) genomic RNA in HeLa cells has previously been found to start at distinct sites at the nuclear periphery. In the present study, the earliest steps in the virus replication cycle, i.e. the appearance and intracellular translocation of viral protein and negative-strand RNA prior to positive-strand RNA synthesis, were followed. During translation, positive-strand RNA and newly synthesized viral protein presented as a dispersed endoplasmic reticulum (ER)-like pattern. Concomitant with translation, individual PV vesicle clusters emerged at the ER and formed nascent replication complexes, which contained newly synthesized negative-strand RNA. The complexes rapidly moved centripetally, in a microtubule-dependent way, to the perinuclear area to engage in positive-strand viral RNA synthesis. Replication complexes made transcriptionally silent with guanidine/HCl followed the anterograde membrane pathway to the Golgi complex within the microtubule-organizing centre (MTOC), whereas replication complexes active in positive-strand RNA synthesis were retained at the nuclear periphery. If the silent replication complexes that had accumulated at the MTOC were released from the guanidine block, transcription was not readily resumed. Rather, positive-strand RNA was redistributed back to the ER to start, after a lag phase, translation, followed by negative- and positive-strand RNA synthesis in replication complexes migrating to the nuclear periphery. As some of the findings appear to be in contrast to events reported in cell-free guanidine-synchronized translation/transcription systems, implications for the comparison of in vitro systems with the living cell are discussed.
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Affiliation(s)
- Denise Egger
- Institute for Medical Microbiology, University of Basel, Petersplatz 10, CH-4000 Basel, Switzerland
| | - Kurt Bienz
- Institute for Medical Microbiology, University of Basel, Petersplatz 10, CH-4000 Basel, Switzerland
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26
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Zhang J, Simon AE. Importance of sequence and structural elements within a viral replication repressor. Virology 2005; 333:301-15. [PMID: 15721364 DOI: 10.1016/j.virol.2004.12.015] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2004] [Revised: 11/17/2004] [Accepted: 12/09/2004] [Indexed: 11/21/2022]
Abstract
Efficient replication of plus-strand RNA viruses requires a 3' proximal core promoter and an increasingly diverse inventory of supporting elements such as enhancers, repressors, and 5' terminal sequences. While core promoters have been well characterized, much less is known about structure-functional relationships of these supporting elements. Members of the genus Carmovirus family Tombusviridae contain a hairpin (H5) proximal to the core promoter that functions as a repressor of minus-strand synthesis in vitro through an interaction between its large symmetrical internal loop (LSL) and 3' terminal bases. Turnip crinkle virus satellite RNA satC with the H5 of carmovirus Japanese iris necrosis virus or Cardamine chlorotic fleck virus (CCFV) did not accumulate to detectable levels even though 3' end base-pairing would be maintained. Replacement of portions of the satC H5 with analogous portions from CCFV revealed that the cognate LSL and lower stem were of greater importance for satC accumulation than the upper stem. In vivo selex of the H5 upper stem and terminal GNRA tetraloop revealed considerable plasticity in the upper stem, including the presence of three- to six-base terminal loops, allowed for H5 function. In vivo selex of the lower stem revealed that both a stable stem and specific base pairs contributed to satC fitness. Surprisingly, mutations in H5 had a disproportionate effect on plus-strand accumulation that was unrelated to the stability of the mutant plus-strands. In addition, fitness to accumulate in plants did not always correlate with enhanced ability to accumulate in protoplasts, suggesting that H5 may be multifunctional.
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Affiliation(s)
- Jiuchun Zhang
- Department of Cell Biology and Molecular Genetics, 1109 Microbiology Building, University of Maryland, College Park, MD 20742, USA
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