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Zhao D, Wang Q, Wang M, Lyu L, Liu S, Jiang Y, Zhou S, Liu F. A putative wild-type or wild-type-like hairpin structure is required within 3' untranslated region of Senecavirus A for virus replication. Virology 2023; 585:72-77. [PMID: 37307649 DOI: 10.1016/j.virol.2023.05.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2023] [Revised: 05/18/2023] [Accepted: 05/22/2023] [Indexed: 06/14/2023]
Abstract
The 3' untranslated region (UTR) of Senecavirus A (SVA) was predicted to harbor two hairpin structures, hairpin-I and -II. The former is composed of two internal loops, one terminal loop and three stem regions; the latter comprises one internal loop, one terminal loop and two stem regions. In this study, we constructed a total of nine SVA cDNA clones, which contained different point mutations within a stem-formed motif in the hairpin-I or -II, for rescuing replication-competent viruses. Only three mutants were successfully rescued and moreover genetically stable during at least five serial passages. Computer-aided prediction showed these three mutants bearing either a wild-type or a wild-type-like hairpin-I in their individual 3' UTRs. Neither wild-type nor wild-type-like hairpin-I could be computationally predicted to exist in 3' UTRs of the other six unviable "viruses". The results suggested that the wild-type or wild-type-like hairpin-I was necessary in the 3' UTR for SVA replication.
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Affiliation(s)
- Di Zhao
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, 266109, China; College of Veterinary Medicine, Inner Mongolia Agricultural University, Huhhot, 010018, China
| | - Qianqian Wang
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, 266109, China; College of Veterinary Medicine, Inner Mongolia Agricultural University, Huhhot, 010018, China
| | - Mengyao Wang
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, 266109, China
| | - Liangpeng Lyu
- Qingdao Workstation of Animal Husbandry, Qingdao, 266199, China
| | - Shuqing Liu
- Qingdao Center for Animal Disease Control & Prevention, Qingdao, 266199, China
| | - Yujia Jiang
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, 266109, China
| | - Shuning Zhou
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, 266109, China
| | - Fuxiao Liu
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao, 266109, China.
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2
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Penza V, Maroun JW, Nace RA, Schulze AJ, Russell SJ. Polycytidine tract deletion from microRNA-detargeted oncolytic Mengovirus optimizes the therapeutic index in a murine multiple myeloma model. Mol Ther Oncolytics 2023; 28:15-30. [PMID: 36619293 PMCID: PMC9800256 DOI: 10.1016/j.omto.2022.11.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Accepted: 11/29/2022] [Indexed: 12/03/2022] Open
Abstract
Mengovirus is an oncolytic picornavirus whose broad host range allows for testing in immunocompetent cancer models. Two pathogenicity-ablating approaches, polycytidine (polyC) tract truncation and microRNA (miRNA) targets insertion, eliminated the risk of encephalomyocarditis. To investigate whether a polyC truncated, miRNA-detargeted oncolytic Mengovirus might be boosted, we partially or fully rebuilt the polyC tract into the 5' noncoding region (NCR) of polyC-deleted (MC0) oncolytic constructs (NC) carrying miRNA target (miRT) insertions to eliminate cardiac/muscular (miR-133b and miR-208a) and neuronal (miR-124) tropisms. PolyC-reconstituted viruses (MC24-NC and MC37-NC) replicated in vitro and showed the expected tropism restrictions, but reduced cytotoxicity and miRT deletions were frequently observed. In the MPC-11 immune competent mouse plasmacytoma model, both intratumoral and systemic administration of MC0-NC led to faster tumor responses than MC24-NC or MC37-NC, with combined durable complete response rates of 75%, 0.5%, and 30%, respectively. Secondary viremia was higher following MC0-NC versus MC24-NC or MC37-NC therapy. Sequence analysis of virus progeny from treated mice revealed a high prevalence of miRT sequences loss among MC24- and MC37- viral genomes, but not in MC0-NC. Overall, MC0-NC was capable of stably retaining miRT sites and provided a more effective treatment and is therefore our lead Mengovirus candidate for clinical translation.
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Affiliation(s)
- Velia Penza
- Mayo Clinic Graduate School of Biomedical Sciences, Mayo Clinic, Rochester, MN 55902, USA
- Department of Molecular Medicine, Mayo Clinic, Rochester, MN 55902, USA
| | - Justin W. Maroun
- Mayo Clinic Alix School of Medicine, Mayo Clinic, Rochester, MN 55902, USA
- Department of Molecular Medicine, Mayo Clinic, Rochester, MN 55902, USA
| | - Rebecca A. Nace
- Department of Molecular Medicine, Mayo Clinic, Rochester, MN 55902, USA
| | - Autumn J. Schulze
- Department of Molecular Medicine, Mayo Clinic, Rochester, MN 55902, USA
| | - Stephen J. Russell
- Mayo Clinic Alix School of Medicine, Mayo Clinic, Rochester, MN 55902, USA
- Department of Molecular Medicine, Mayo Clinic, Rochester, MN 55902, USA
- Division of Hematology, Mayo Clinic, Rochester, MN, USA
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3
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Francisco-Velilla R, Embarc-Buh A, Abellan S, Martinez-Salas E. Picornavirus translation strategies. FEBS Open Bio 2022; 12:1125-1141. [PMID: 35313388 PMCID: PMC9157412 DOI: 10.1002/2211-5463.13400] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 02/02/2022] [Accepted: 03/18/2022] [Indexed: 12/15/2022] Open
Abstract
The genome of viruses classified as picornaviruses consists of a single monocistronic positive strand RNA. The coding capacity of these RNA viruses is rather limited, and thus, they rely on the cellular machinery for their viral replication cycle. Upon the entry of the virus into susceptible cells, the viral RNA initially competes with cellular mRNAs for access to the protein synthesis machinery. Not surprisingly, picornaviruses have evolved specialized strategies that successfully allow the expression of viral gene products, which we outline in this review. The main feature of all picornavirus genomes is the presence of a heavily structured RNA element on the 5´UTR, referred to as an internal ribosome entry site (IRES) element, which directs viral protein synthesis as well and, consequently, triggers the subsequent steps required for viral replication. Here, we will summarize recent studies showing that picornavirus IRES elements consist of a modular structure, providing sites of interaction for ribosome subunits, eIFs, and a selective group of RNA‐binding proteins.
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Affiliation(s)
| | - Azman Embarc-Buh
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Madrid, Spain
| | - Salvador Abellan
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Madrid, Spain
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Xiong J, Cui X, Zhao K, Wang Q, Huang X, Li D, Yu F, Yang Y, Liu D, Tian Z, Cai X, An T. A Novel Motif in the 3′-UTR of PRRSV-2 Is Critical for Viral Multiplication and Contributes to Enhanced Replication Ability of Highly Pathogenic or L1 PRRSV. Viruses 2022; 14:v14020166. [PMID: 35215760 PMCID: PMC8875199 DOI: 10.3390/v14020166] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 01/13/2022] [Accepted: 01/14/2022] [Indexed: 11/16/2022] Open
Abstract
Highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) with enhanced replication capability emerged in China and has become dominant epidemic strain since 2006. Up to now, the replication-regulated genes of PRRSV have not been fully clarified. Here, by swapping the genes or elements between HP-PRRSV and classical PRRSV based on infectious clones, NSP1, NSP2, NSP7, NSP9 and 3′-UTR are found to contribute to the high replication efficiency of HP-PRRSV. Further study revealed that mutations at positions 117th or 119th in the 3′-UTR are significantly related to replication efficiency, and the nucleotide at position 120th is critical for viral rescue. The motif composed by 117–120th nucleotides was quite conservative within each lineage of PRRSV; mutations in the motif of HP-PRRSV and currently epidemic lineage 1 (L1) PRRSV showed higher synthesis ability of viral negative genomic RNA, suggesting that those mutations were beneficial for viral replication. RNA structure analysis revealed that this motif maybe involved into a pseudoknot in the 3′-UTR. The results discovered a novel motif, 117–120th nucleotide in the 3′-UTR, that is critical for replication of PRRSV-2, and mutations in the motif contribute to the enhanced replicative ability of HP-PRRSV or L1 PRRSV. Our findings will help to understand the molecular basis of PRRSV replication and find the potential factors resulting in an epidemic strain of PRRSV.
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Affiliation(s)
- Junyao Xiong
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China; (J.X.); (X.C.); (K.Z.); (Q.W.); (X.H.); (D.L.); (F.Y.); (Y.Y.); (Z.T.); (X.C.)
| | - Xingyang Cui
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China; (J.X.); (X.C.); (K.Z.); (Q.W.); (X.H.); (D.L.); (F.Y.); (Y.Y.); (Z.T.); (X.C.)
| | - Kuan Zhao
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China; (J.X.); (X.C.); (K.Z.); (Q.W.); (X.H.); (D.L.); (F.Y.); (Y.Y.); (Z.T.); (X.C.)
| | - Qian Wang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China; (J.X.); (X.C.); (K.Z.); (Q.W.); (X.H.); (D.L.); (F.Y.); (Y.Y.); (Z.T.); (X.C.)
| | - Xinyi Huang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China; (J.X.); (X.C.); (K.Z.); (Q.W.); (X.H.); (D.L.); (F.Y.); (Y.Y.); (Z.T.); (X.C.)
| | - Dongyan Li
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China; (J.X.); (X.C.); (K.Z.); (Q.W.); (X.H.); (D.L.); (F.Y.); (Y.Y.); (Z.T.); (X.C.)
| | - Fang Yu
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China; (J.X.); (X.C.); (K.Z.); (Q.W.); (X.H.); (D.L.); (F.Y.); (Y.Y.); (Z.T.); (X.C.)
| | - Yongbo Yang
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China; (J.X.); (X.C.); (K.Z.); (Q.W.); (X.H.); (D.L.); (F.Y.); (Y.Y.); (Z.T.); (X.C.)
| | - Di Liu
- Institute of Animal Husbandry, Heilongjiang Academy of Agricultural Sciences, Harbin 150086, China;
| | - Zhijun Tian
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China; (J.X.); (X.C.); (K.Z.); (Q.W.); (X.H.); (D.L.); (F.Y.); (Y.Y.); (Z.T.); (X.C.)
| | - Xuehui Cai
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China; (J.X.); (X.C.); (K.Z.); (Q.W.); (X.H.); (D.L.); (F.Y.); (Y.Y.); (Z.T.); (X.C.)
| | - Tongqing An
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150069, China; (J.X.); (X.C.); (K.Z.); (Q.W.); (X.H.); (D.L.); (F.Y.); (Y.Y.); (Z.T.); (X.C.)
- Correspondence: ; Tel.: +86-451-5105-1765; Fax: +86-451-5199-7166
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5
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Translation of Plant RNA Viruses. Viruses 2021; 13:v13122499. [PMID: 34960768 PMCID: PMC8708638 DOI: 10.3390/v13122499] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2021] [Revised: 12/01/2021] [Accepted: 12/09/2021] [Indexed: 11/16/2022] Open
Abstract
Plant RNA viruses encode essential viral proteins that depend on the host translation machinery for their expression. However, genomic RNAs of most plant RNA viruses lack the classical characteristics of eukaryotic cellular mRNAs, such as mono-cistron, 5′ cap structure, and 3′ polyadenylation. To adapt and utilize the eukaryotic translation machinery, plant RNA viruses have evolved a variety of translation strategies such as cap-independent translation, translation recoding on initiation and termination sites, and post-translation processes. This review focuses on advances in cap-independent translation and translation recoding in plant viruses.
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Kloc A, Rai DK, Rieder E. The Roles of Picornavirus Untranslated Regions in Infection and Innate Immunity. Front Microbiol 2018; 9:485. [PMID: 29616004 PMCID: PMC5870040 DOI: 10.3389/fmicb.2018.00485] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 02/28/2018] [Indexed: 11/17/2022] Open
Abstract
Viral genomes have evolved to maximize their potential of overcoming host defense mechanisms and to induce a variety of disease syndromes. Structurally, a genome of a virus consists of coding and noncoding regions, and both have been shown to contribute to initiation and progression of disease. Accumulated work in picornaviruses has stressed out the importance of the noncoding RNAs, or untranslated 5′- and 3′-regions (UTRs), in both replication and translation of viral genomes. Unsurprisingly, defects in these processes have been reported to cause viral attenuation and affect viral pathogenicity. However, substantial evidence suggests that these untranslated RNAs may influence the outcome of the host innate immune response. This review discusses the involvement of 5′- and 3′-terminus UTRs in induction and regulation of host immunity and its consequences for viral life cycle and virulence.
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Affiliation(s)
- Anna Kloc
- Foreign Animal Disease Research Unit, Plum Island Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Greenport, NY, United States
| | - Devendra K Rai
- Foreign Animal Disease Research Unit, Plum Island Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Greenport, NY, United States
| | - Elizabeth Rieder
- Foreign Animal Disease Research Unit, Plum Island Animal Disease Center, Agricultural Research Service, United States Department of Agriculture, Greenport, NY, United States
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7
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Abstract
Reproduction of RNA viruses is typically error-prone due to the infidelity of their replicative machinery and the usual lack of proofreading mechanisms. The error rates may be close to those that kill the virus. Consequently, populations of RNA viruses are represented by heterogeneous sets of genomes with various levels of fitness. This is especially consequential when viruses encounter various bottlenecks and new infections are initiated by a single or few deviating genomes. Nevertheless, RNA viruses are able to maintain their identity by conservation of major functional elements. This conservatism stems from genetic robustness or mutational tolerance, which is largely due to the functional degeneracy of many protein and RNA elements as well as to negative selection. Another relevant mechanism is the capacity to restore fitness after genetic damages, also based on replicative infidelity. Conversely, error-prone replication is a major tool that ensures viral evolvability. The potential for changes in debilitated genomes is much higher in small populations, because in the absence of stronger competitors low-fit genomes have a choice of various trajectories to wander along fitness landscapes. Thus, low-fit populations are inherently unstable, and it may be said that to run ahead it is useful to stumble. In this report, focusing on picornaviruses and also considering data from other RNA viruses, we review the biological relevance and mechanisms of various alterations of viral RNA genomes as well as pathways and mechanisms of rehabilitation after loss of fitness. The relationships among mutational robustness, resilience, and evolvability of viral RNA genomes are discussed.
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8
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MicroRNA-Detargeted Mengovirus for Oncolytic Virotherapy. J Virol 2016; 90:4078-4092. [PMID: 26865716 PMCID: PMC4810567 DOI: 10.1128/jvi.02810-15] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 01/31/2016] [Indexed: 12/12/2022] Open
Abstract
Mengovirus, a member of the Picornaviridae family, has a broad cell tropism and can cause encephalitis and myocarditis in multiple mammalian species. Attenuation has been achieved by shortening the polycytidine tract in the 5′ noncoding region (NCR). A poly(C)-truncated strain of mengovirus, vMC24, resulted in significant tumor regression in immunocompetent BALB/c mice bearing syngeneic MPC-11 plasmacytomas, but the associated toxicities were unacceptable. To enhance its safety profile, microRNA target sequences complementary to miR-124 or miR-125 (enriched in nervous tissue), miR-133 and miR-208 (enriched in cardiac tissue), or miR-142 (control; enriched in hematopoietic tissues) were inserted into the vMC24 NCRs. The microRNA-detargeted viruses showed reduced replication and cell killing specifically in cells expressing the cognate microRNAs, but certain insertions additionally were associated with nonspecific suppression of viral fitness in vivo. In vivo toxicity testing confirmed that miR-124 targets within the 5′ NCR suppressed virus replication in the central nervous system while miR-133 and miR-208 targets in the 3′ NCR suppressed viral replication in cardiac tissue. A dual-detargeted virus named vMC24-NC, with miR-124 targets in the 5′ NCR and miR-133 plus miR-208 targets in the 3′ NCR, showed the suppression of replication in both nervous and cardiac tissues but retained full oncolytic potency when administered by intratumoral (106 50% tissue culture infectious doses [TCID50]) or intravenous (107 to 108 TCID50) injection into BALB/c mice bearing MPC-11 plasmacytomas. Overall survival of vMC24-NC-treated tumor-bearing mice was significantly improved compared to that of nontreated mice. MicroRNA-detargeted mengoviruses offer a promising oncolytic virotherapy platform that merits further development for clinical translation. IMPORTANCE The clinical potential of oncolytic virotherapy for cancer treatment has been well demonstrated, justifying the continued development of novel oncolytic viruses with enhanced potency. Here, we introduce mengovirus as a novel oncolytic agent. Mengovirus is appealing as an oncolytic virotherapy platform because of its small size, simple genome structure, rapid replication cycle, and broad cell/species tropism. However, mengovirus can cause encephalomyelitis and myocarditis. It can be partially attenuated by shortening the poly(C) tract in the 5′ NCR but remains capable of damaging cardiac and nervous tissue. Here, we further enhanced the safety profile of a poly(C)-truncated mengovirus by incorporating muscle- and neuron-specific microRNA target sequences into the viral genome. This dual-detargeted virus has reduced pathogenesis but retained potent oncolytic activity. Our data show that microRNA targeting can be used to further increase the safety of an attenuated mengovirus, providing a basis for its development as an oncolytic platform.
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9
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Lozano G, Fernandez N, Martinez-Salas E. Modeling Three-Dimensional Structural Motifs of Viral IRES. J Mol Biol 2016; 428:767-776. [PMID: 26778619 DOI: 10.1016/j.jmb.2016.01.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 01/08/2016] [Accepted: 01/08/2016] [Indexed: 01/23/2023]
Abstract
RNA virus genomes are reservoirs of a wide diversity of RNA structural elements. In particular, specific regions of the viral genome have evolved to adopt specialized three-dimensional (3D) structures, which can act in concert with host factors and/or viral proteins to recruit the translation machinery on viral RNA using a mechanism that is independent on the 5' end. This strategy relies on cis-acting RNA sequences designated as internal ribosome entry site (IRES) elements. IRES elements that are found in the genome of different groups of RNA viruses perform the same function despite differing in primary sequence and secondary RNA structure and host factor requirement to recruit the translation machinery internally. Evolutionarily conserved motifs tend to preserve sequences in each group of RNA viruses impacting on RNA structure and RNA-protein interactions important for IRES function. However, due to the lack of sequence homology among genetically distant IRES elements, accurate modeling of 3D IRES structure is currently a challenging task. In addition, as a universal RNA motif unique to IRES elements has not been found, a better understanding of viral IRES structural motifs could greatly assist in the detection of IRES-like motifs hidden in genome sequences. The focus of this review is to describe recent advances in modeling viral IRES tertiary structural motifs and also novel approaches to detect sequences potentially folding as IRES-like motifs.
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Affiliation(s)
- Gloria Lozano
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas Universidad Autónoma de Madrid, Nicolas Cabrera 1, 28049 Madrid, Spain
| | - Noemi Fernandez
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas Universidad Autónoma de Madrid, Nicolas Cabrera 1, 28049 Madrid, Spain
| | - Encarnacion Martinez-Salas
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas Universidad Autónoma de Madrid, Nicolas Cabrera 1, 28049 Madrid, Spain.
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10
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Martínez-Salas E, Francisco-Velilla R, Fernandez-Chamorro J, Lozano G, Diaz-Toledano R. Picornavirus IRES elements: RNA structure and host protein interactions. Virus Res 2015; 206:62-73. [PMID: 25617758 DOI: 10.1016/j.virusres.2015.01.012] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 01/05/2015] [Accepted: 01/12/2015] [Indexed: 01/26/2023]
Abstract
Internal ribosome entry site (IRES) elements were discovered in picornaviruses. These elements are cis-acting RNA sequences that adopt diverse three-dimensional structures and recruit the translation machinery using a 5' end-independent mechanism assisted by a subset of translation initiation factors and various RNA binding proteins termed IRES transacting factors (ITAFs). Many of these factors suffer important modifications during infection including cleavage by picornavirus proteases, changes in the phosphorylation level and/or redistribution of the protein from the nuclear to the cytoplasm compartment. Picornavirus IRES are amongst the most potent elements described so far. However, given their large diversity and complexity, the mechanistic basis of its mode of action is not yet fully understood. This review is focused to describe recent advances on the studies of RNA structure and RNA-protein interactions modulating picornavirus IRES activity.
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Affiliation(s)
- Encarnación Martínez-Salas
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas - Universidad Autónoma de Madrid, Nicolas Cabrera 1, 28049 Madrid, Spain.
| | - Rosario Francisco-Velilla
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas - Universidad Autónoma de Madrid, Nicolas Cabrera 1, 28049 Madrid, Spain
| | - Javier Fernandez-Chamorro
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas - Universidad Autónoma de Madrid, Nicolas Cabrera 1, 28049 Madrid, Spain
| | - Gloria Lozano
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas - Universidad Autónoma de Madrid, Nicolas Cabrera 1, 28049 Madrid, Spain
| | - Rosa Diaz-Toledano
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas - Universidad Autónoma de Madrid, Nicolas Cabrera 1, 28049 Madrid, Spain
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11
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Paul AV, Wimmer E. Initiation of protein-primed picornavirus RNA synthesis. Virus Res 2015; 206:12-26. [PMID: 25592245 DOI: 10.1016/j.virusres.2014.12.028] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 12/16/2014] [Accepted: 12/24/2014] [Indexed: 12/14/2022]
Abstract
Plus strand RNA viruses use different mechanisms to initiate the synthesis of their RNA chains. The Picornaviridae family constitutes a large group of plus strand RNA viruses that possess a small terminal protein (VPg) covalently linked to the 5'-end of their genomes. The RNA polymerases of these viruses use VPg as primer for both minus and plus strand RNA synthesis. In the first step of the initiation reaction the RNA polymerase links a UMP to the hydroxyl group of a tyrosine in VPg using as template a cis-replicating element (cre) positioned in different regions of the viral genome. In this review we will summarize what is known about the initiation reaction of protein-primed RNA synthesis by the RNA polymerases of the Picornaviridae. As an example we will use the RNA polymerase of poliovirus, the prototype of Picornaviridae. We will also discuss models of how these nucleotidylylated protein primers might be used, together with viral and cellular replication proteins and other cis-replicating RNA elements, during minus and plus strand RNA synthesis.
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Affiliation(s)
- Aniko V Paul
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY 11790, United States.
| | - Eckard Wimmer
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY 11790, United States
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12
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Kemenesi G, Zhang D, Marton S, Dallos B, Görföl T, Estók P, Boldogh S, Kurucz K, Oldal M, Kutas A, Bányai K, Jakab F. Genetic characterization of a novel picornavirus detected in Miniopterus schreibersii bats. J Gen Virol 2014; 96:815-821. [PMID: 25516541 DOI: 10.1099/jgv.0.000028] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Bats are important reservoirs of many viruses with zoonotic potential worldwide, including Europe. Among bat viruses, members of the Picornaviridae family remain a neglected group. We performed viral metagenomic analyses on Miniopterus schreibersii bat faecal samples, collected in Hungary in 2013. In the present study we report the first molecular data and genomic characterization of a novel picornavirus from the bat species M. schreibersii in Europe. Based on phylogenetic analyses, the novel bat picornaviruses unambiguously belong to the Mischivirus genus and were highly divergent from other bat-derived picornaviruses of the Sapelovirus genus. Although the Hungarian viruses were most closely related to Mischivirus A, they formed a separate monophyletic branch within the genus.
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Affiliation(s)
- Gábor Kemenesi
- Institute of Biology, Faculty of Sciences, University of Pécs, Pécs, Hungary
- Virological Research Group, János Szentágothai Research Center, University of Pécs, Pécs, Hungary
| | - Dabing Zhang
- Key Laboratory of Animal Epidemiology and Zoonosis of Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, PR China
| | - Szilvia Marton
- Institute for Veterinary Medical Research, Centre for Agricultural Research, Hungarian Academy of Sciences, Budapest, Hungary
| | - Bianka Dallos
- Institute of Biology, Faculty of Sciences, University of Pécs, Pécs, Hungary
- Virological Research Group, János Szentágothai Research Center, University of Pécs, Pécs, Hungary
| | - Tamás Görföl
- Department of Zoology, Hungarian Natural History Museum, Budapest, Hungary
- Institute for Veterinary Medical Research, Centre for Agricultural Research, Hungarian Academy of Sciences, Budapest, Hungary
| | - Péter Estók
- Department of Zoology, Eszterházy Károly College, Eger, Hungary
| | | | - Kornélia Kurucz
- Institute of Biology, Faculty of Sciences, University of Pécs, Pécs, Hungary
| | - Miklós Oldal
- Institute of Biology, Faculty of Sciences, University of Pécs, Pécs, Hungary
- Virological Research Group, János Szentágothai Research Center, University of Pécs, Pécs, Hungary
| | - Anna Kutas
- Institute of Biology, Faculty of Sciences, University of Pécs, Pécs, Hungary
- Virological Research Group, János Szentágothai Research Center, University of Pécs, Pécs, Hungary
| | - Krisztián Bányai
- Institute for Veterinary Medical Research, Centre for Agricultural Research, Hungarian Academy of Sciences, Budapest, Hungary
| | - Ferenc Jakab
- Institute of Biology, Faculty of Sciences, University of Pécs, Pécs, Hungary
- Virological Research Group, János Szentágothai Research Center, University of Pécs, Pécs, Hungary
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13
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Abstract
The genomic RNA of poliovirus and closely related picornaviruses perform template and non-template functions during viral RNA replication. The non-template functions are mediated by cis-active RNA sequences that bind viral and cellular proteins to form RNP complexes. The RNP complexes mediate temporally dynamic, long-range interactions in the viral genome and ensure the specificity of replication. The 5' cloverleaf (5' CL)-RNP complex serves as a key cis-active element in all of the non-template functions of viral RNA. The 5'CL-RNP complex is proposed to interact with the cre-RNP complex during VPgpUpU synthesis, the 3'NTR-poly(A) RNP complex during negative-strand initiation and the 30 end negative-strand-RNP complex during positive-strand initiation. Co-ordinating these long-range interactions is important in regulating each step in the replication cycle.
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Affiliation(s)
- Sushma A Ogram
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, FL 32610, United States
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14
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Liu Y, Wimmer E, Paul AV. Cis-acting RNA elements in human and animal plus-strand RNA viruses. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2009; 1789:495-517. [PMID: 19781674 PMCID: PMC2783963 DOI: 10.1016/j.bbagrm.2009.09.007] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/04/2009] [Revised: 09/09/2009] [Accepted: 09/13/2009] [Indexed: 02/08/2023]
Abstract
The RNA genomes of plus-strand RNA viruses have the ability to form secondary and higher-order structures that contribute to their stability and to their participation in inter- and intramolecular interactions. Those structures that are functionally important are called cis-acting RNA elements because their functions cannot be complemented in trans. They can be involved not only in RNA/RNA interactions but also in binding of viral and cellular proteins during the complex processes of translation, RNA replication and encapsidation. Most viral cis-acting RNA elements are located in the highly structured 5'- and 3'-nontranslated regions of the genomes but sometimes they also extend into the adjacent coding sequences. In addition, some cis-acting RNA elements are embedded within the coding sequences far away from the genomic ends. Although the functional importance of many of these structures has been confirmed by genetic and biochemical analyses, their precise roles are not yet fully understood. In this review we have summarized what is known about cis-acting RNA elements in nine families of human and animal plus-strand RNA viruses with an emphasis on the most thoroughly characterized virus families, the Picornaviridae and Flaviviridae.
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Affiliation(s)
- Ying Liu
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY 11790, USA
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15
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Zoll J, Heus HA, van Kuppeveld FJM, Melchers WJG. The structure-function relationship of the enterovirus 3'-UTR. Virus Res 2008; 139:209-16. [PMID: 18706945 DOI: 10.1016/j.virusres.2008.07.014] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2008] [Accepted: 07/02/2008] [Indexed: 12/25/2022]
Abstract
Essential processes in living cells are carried out by large complex assemblies, which typically consist of a large number of proteins and frequently also contain nucleic acids, mostly RNA [Alberts, B., 1998. The cell as a collection of protein machines: preparing the next generation of molecular biologists. Cell 92, 291-294]. These large biomolecular complexes carry out biological processes in highly sophisticated ways: molecules do not move around randomly in the cell and interact by chance, but are guided to these "macromolecular machines", in which the number of possible collisions is restricted to a few possibilities, based, e.g., on the specificity of protein-RNA recognition. While the coding capacity of RNA lies within its sequence, the shape of an RNA molecule determines other functionalities such as stability, intra- and intermolecular interactions, catalytic activity, regulation of cellular processes, etc. [Doudna, J.A., 2000. Structural genomics of RNA. Nat. Struct. Biol. 7, 954-956; Cech, T.R. 2000. Structural biology. The ribosome is a ribozyme. Science 289, 878-879]. RNA structures in macromolecular machines are important features in assembly, target recognition and activity. Viral RNA molecules contain cis- and/or trans-acting control elements that, as exemplified by internal ribosomal entry sites and origins of genome replication, consist of complex multidomain structures [Andino, R., Rieckhof, G.E., Achacoso, P.L., Baltimore D., 1993. Poliovirus RNA synthesis utilizes an RNP complex formed around the 5'-end of viral RNA. EMBO J. 12, 3587-3598; Melchers, W.J.G., Hoenderop, J.G.J., Bruins Slot, H.J., Pleij, C.W.A., Pilipenko, E.V., Agol, V.I., Galama, J.M.D., 1997. Kissing of the two predominant hairpin loops in the coxsackie B virus 3' untranslated region is the essential structural feature of the origin of replication required for negative-strand RNA synthesis. J. Virol. 71, 686-696]. The formation of these structures is involved in the specific recognition of ligands or serves to support the structural integrity of the whole element. The replication of the enterovirus RNA is carried out by a large biomolecular complex formed by cis-acting RNA elements found in the 5'- and 3'-UTR of the virus genome and several cellular and viral proteins. This review will focus on RNA elements in the 3'-UTR of enteroviruses.
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Affiliation(s)
- Jan Zoll
- Radboud University Nijmegen Medical Centre, Nijmegen Centre for Molecular Life Sciences, Department of Medical Microbiology, PO Box 9101, 6500 HB Nijmegen, The Netherlands.
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16
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Cordey S, Gerlach D, Junier T, Zdobnov EM, Kaiser L, Tapparel C. The cis-acting replication elements define human enterovirus and rhinovirus species. RNA (NEW YORK, N.Y.) 2008; 14:1568-1578. [PMID: 18541697 PMCID: PMC2491478 DOI: 10.1261/rna.1031408] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2008] [Accepted: 04/24/2008] [Indexed: 05/26/2023]
Abstract
Replication of picornaviruses is dependent on VPg uridylylation, which is linked to the presence of the internal cis-acting replication element (cre). Cre are located within the sequence encoding polyprotein, yet at distinct positions as demonstrated for poliovirus and coxsackievirus-B3, cardiovirus, and human rhinovirus (HRV-A and HRV-B), overlapping proteins 2C, VP2, 2A, and VP1, respectively. Here we report a novel distinct cre element located in the VP2 region of the recently reported HRV-A2 species and provide evolutionary evidence of its functionality. We also experimentally interrogated functionality of recently identified HRV-B cre in the 2C region that is orthologous to the human enterovirus (HEV) cre and show that it is dispensable for replication and appears to be a nonfunctional evolutionary relic. In addition, our mutational analysis highlights two amino acids in the 2C protein that are crucial for replication. Remarkably, we conclude that each genetic clade of HRV and HEV is characterized by a unique functional cre element, where evolutionary success of a new genetic lineage seems to be associated with an invention of a novel cre motif and decay of the ancestral one. Therefore, we propose that cre element could be considered as an additional criterion for human rhinovirus and enterovirus classification.
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Affiliation(s)
- Samuel Cordey
- Central Laboratory of Virology, Division of Infectious Diseases, University of Geneva Hospitals, 1211 Geneva 14, Switzerland.
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17
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De Jesus NH. Epidemics to eradication: the modern history of poliomyelitis. Virol J 2007; 4:70. [PMID: 17623069 PMCID: PMC1947962 DOI: 10.1186/1743-422x-4-70] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2007] [Accepted: 07/10/2007] [Indexed: 11/13/2022] Open
Abstract
Poliomyelitis has afflicted humankind since antiquity, and for nearly a century now, we have known the causative agent, poliovirus. This pathogen is an enterovirus that in recent history has been the source of a great deal of human suffering. Although comparatively small, its genome is packed with sufficient information to make it a formidable pathogen. In the last 20 years the Global Polio Eradication Initiative has proven successful in greatly diminishing the number of cases worldwide but has encountered obstacles in its path which have made halting the transmission of wild polioviruses a practical impossibility. As we begin to realize that a change in strategy may be crucial in achieving success in this venture, it is imperative that we critically evaluate what is known about the molecular biology of this pathogen and the intricacies of its interaction with its host so that in future attempts we may better equipped to more effectively combat this important human pathogen.
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Affiliation(s)
- Nidia H De Jesus
- Department of Molecular Genetics & Microbiology, Stony Brook University School of Medicine, Stony Brook, New York, USA.
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18
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Abstract
Foot-and-mouth disease virus (FMDV) RNA is infectious. After delivery of the RNA (about 8.3 kb) into the cytoplasm of a cell, the RNA must initially be translated to produce the viral proteins required for RNA replication and for the packaging of the RNA into new virions. Subsequently there has to be a switch in the function of the RNA; translation has to be stopped to permit RNA replication. The signals required for the control of the different roles of viral RNA must be included within the viral RNA sequence. Many cellular proteins interact with the viral RNA and probably also with the virus-encoded proteins. The functions of different RNA elements within the viral RNA and the various virus-encoded proteins in determining the efficiency of virus replication are discussed. Unique aspects of FMDV RNA translation and replication are emphasised.
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Affiliation(s)
- G J Belsham
- BBSRC Institute for Animal Health, Pirbright, Woking, Surrey, GU24 ONF, UK.
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19
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Brown DM, Cornell CT, Tran GP, Nguyen JHC, Semler BL. An authentic 3' noncoding region is necessary for efficient poliovirus replication. J Virol 2005; 79:11962-73. [PMID: 16140772 PMCID: PMC1212627 DOI: 10.1128/jvi.79.18.11962-11973.2005] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Picornavirus RNA replication involves the specific synthesis of negative-strand intermediates followed by an accumulation of positive-strand viral RNA in the presence of a multitude of cellular mRNAs. Previously, in an effort to identify cis-acting elements required for initiation of negative-strand RNA synthesis, we deleted the entire 3' noncoding regions from human rhinovirus and poliovirus genomic RNAs. These deletion mutation transcripts displayed a severe delay in RNA accumulation following transfection of HeLa cells. Interestingly, in subsequent infection of HeLa cells, the deletion-mutant poliovirus displayed only a moderate deficiency in RNA synthesis. These data suggested that the delay in the production of cytopathic effects after transfection may have been due to an RNA replication defect overcome by the accumulation of a compensatory mutation(s) generated during initial rounds of RNA synthesis. In this study, we have sequenced the entire genome of the deletion-mutant virus and found only two nucleotide changes from the parental clone. Transfection analysis of these sequence variants revealed that the sequence changes did not provide compensatory functions for the 3' noncoding region deletion mutation replication defect. Further examination of the deletion mutant phenotype revealed that the severe replication defect following RNA transfection is due, in part, to nonviral terminal sequences present in the in vitro-derived deletion mutation transcripts. Our data suggest that poliovirus RNA harboring a complete 3' noncoding region deletion mutation is infectious (not merely quasi-infectious).
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Affiliation(s)
- David M Brown
- Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, CA 92697, USA
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20
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Abstract
Dipyridamole is an effective inhibitor of cardiovirus growth in cell culture. The effects of dipyridamole on mengovirus replication in vivo and in vitro were examined in the hope the drug could be used as an experimental analog of the poliovirus inhibitor guanidine. Guanidine selectively inhibits poliovirus RNA synthesis but not RNA translation, and as such, has been a valuable research tool. Although guanidine does not inhibit cardiovirus infection, a compound with similar discriminatory characteristics would be experimentally useful for parallel work with these viruses. We found that mengovirus plaque formation in HeLa or L cells was inhibited nearly 100% by the presence of 80 muM dipyridamole. The inhibitory effect was reversible and targeted an early step in the replication cycle. Studies with luciferase-expressing mengovirus replicons showed that viral protein synthesis was unaffected by dipyridamole, and rather, RNA synthesis was the step targeted by the drug. This assessment was confirmed by direct analyses of viral translation and RNA synthesis activities in a Krebs-2-derived in vitro system that supported complete, infectious cardiovirus replication. In Krebs extracts, dipyridamole specifically inhibited viral RNA synthesis to more than 95%, with no concomitant effect on viral protein translation or polyprotein processing. The observed inhibition reversibly affected an early step in both minus-strand and plus-strand RNA synthesis, although inhibition of plus-strand synthesis was more profound than that of minus-strand synthesis. We conclude that dipyridamole is a potent experimental tool that readily distinguishes between cardiovirus translation and RNA replication functions.
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21
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Pankraz A, Thiel HJ, Becher P. Essential and nonessential elements in the 3' nontranslated region of Bovine viral diarrhea virus. J Virol 2005; 79:9119-27. [PMID: 15994806 PMCID: PMC1168729 DOI: 10.1128/jvi.79.14.9119-9127.2005] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The 3' nontranslated region (NTR) of the pestivirus Bovine viral diarrhea virus (BVDV), a close relative of human Hepatitis C virus, consists of three stem-loops which are separated by two single-stranded regions. As in other positive-stranded RNA viruses, the 3' NTR of pestiviruses is involved in crucial processes of the viral life cycle. While several studies characterized cis-acting elements within the 3' NTR of a BVDV replicon, there are no studies addressing the significance of these elements in the context of a replicating virus. To examine the functional importance of 3' NTR elements, a set of 4-base deletions and deletions of each of the three stem-loops were introduced into an infectious BVDV cDNA clone. Emerging mutant viruses were characterized with regard to plaque phenotype, growth kinetics, and synthesis of viral RNA. The results indicated that presence of stem-loop (SL) I and the 3'-terminal part of the single-stranded region between stem-loops I and II are indispensable for pestiviral replication. In contrast, deletions within SL II and SL III as well as absence of either SL II or SL III still allowed efficient viral replication; however, a mutant RNA lacking both SL II and SL III was not infectious. The results of this study provide a detailed map of the essential and nonessential elements within the 3' NTR of BVDV and contribute to our understanding of sequence and structural elements important for efficient viral replication of pestiviruses in natural host cells.
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Affiliation(s)
- Alexander Pankraz
- Institut für Virologie (FB Veterinärmedizin), Justus-Liebig-Universität Giessen, Frankfurter Str. 107, D-35392 Giessen, Germany
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22
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Aminev AG, Amineva SP, Palmenberg AC. Encephalomyocarditis viral protein 2A localizes to nucleoli and inhibits cap-dependent mRNA translation. Virus Res 2003; 95:45-57. [PMID: 12921995 DOI: 10.1016/s0168-1702(03)00162-x] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Panels of monoclonal antibodies were raised against viral non-structural proteins of encephalomyocarditis virus (EMCV) and used to probe infected cells in laser confocal microscopy experiments and Western analyses. Surprisingly, all Mengovirus and EMCV-infected cells showed strong targeting of protein 2A, 3B(VPg), 3C(pro), and 3D(pol) signals to cellular nuclei, in particular to nucleoli, from the earliest times of infection. Viral capsid proteins (1AB, 1C, and 1D) and other non-structural proteins (2B, 2C, and 3A) did not target nuclei and remained cytoplasmic throughout the infection. The cardioviral 2A protein (subject of this article) has a novel 143 amino acid sequence, terminating in a 19 amino acid COOH-terminal processing cassette (PCC) that participates in autocatalytic, co-translational primary cleavage of the viral polyprotein. The remainder of the 2A protein shares only limited similarity with other viral or cellular sequences, except for a short motif (KRvRPFRLP) near PCC resembling the nuclear localization signals (NLS) common to many yeast ribosomal proteins. Deletions within the EMCV 2A protein that impinge on this region have been reported to diminish the ability of virus to inhibit cap-dependent translation of cellular mRNAs. We have now observed that these same deletions prevented nuclear localization. Cellular expression of 2A protein from RNA transcripts or cDNAs confirmed that it does not require other viral proteins or activities for nuclear transport; even when expressed as a single protein, 2A protein effectively shuts off translation from capped reporter mRNAs. Within infected, transfected, or DNA vector-transformed cells, the 2A protein was always found in close association with the nucleolar ribosomal chaperone protein B23, which may help the traffic 2A into nucleoli like a surrogate ribosomal protein, by virtue of the putative nucleolar localization signal (NoLS). The data are consistent with a novel mechanism for virus-induced host protein shut off in cardioviruses, whereby 2A helps to upregulate the synthesis of new and modified ribosomes that have an inherent preference for internal ribosomal entry site (IRES)-dependent viral genome translation over cap-dependent host mRNA translation.
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Affiliation(s)
- Aleksey G Aminev
- Institute for Molecular Virology, University of Wisconsin-Madison, Madison, WI 53706, USA.
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23
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Aminev AG, Amineva SP, Palmenberg AC. Encephalomyocarditis virus (EMCV) proteins 2A and 3BCD localize to nuclei and inhibit cellular mRNA transcription but not rRNA transcription. Virus Res 2003; 95:59-73. [PMID: 12921996 DOI: 10.1016/s0168-1702(03)00163-1] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We have followed the viral processing cascade and polyprotein precursor fates during encephalomyocarditis virus (EMCV) infection of HeLa cells using a panel of monoclonal antibodies (mAbs). Within the first 2-4 h of infection, signals of antibodies specific for the 2A, 3B(VPg), 3C(pro) and 3D(pol) proteins were found to co-localize in nucleoli at the rRNA synthesis and cellular protein B23 (nucleophosmin) sites. Cellular fractionation identified viral protein precursor 3BCD as the common source of the P3-region antibody signals. Previously thought to be a minor product of the polymerase region cleavage pathways, the nuclear targeting of this precursor was localized with engineered mutations to five P2 and P3 region polyprotein processing sites. A nuclear localization motif (NLS), similar to that in many yeast ribosomal proteins, was identified near the N-terminus of the 3D(pol) sequence. Point mutations within this motif prevented nuclear and nucleolar localization by all forms of 3B(VPg), 3C(pro) and 3D(pol), and were lethal to the virus because they also prevented genome replication. However, viral RNA synthesis was not required for nucleolar transport and 3BCD was found in nuclei, even when the 3D(pol) was inactivated. Co-immunoprecipitation experiments showed a tight association between 3BCD and B23 (nucleophosmin), suggesting a possible ribosomal protein-like mechanism for nuclear transport. Infected cell extracts analyzed with microarrays, quantitative slot-blots and pulse-labeling experiments confirmed a nearly complete shutoff of host pol-II-dependent mRNA synthesis during EMCV infection, in reactions that depended on wild-type 2A protein. In contrast to human rhinovirus-16 infection, rRNA synthesis by pol-I and pol-III were not turned off by EMCV, although the cellular concentration of rRNA decreased during infection, relative to control samples. The data suggest that nuclear targeting by 2A and 3BCD may be responsible for regulating cellular mRNA and rRNA transcription during infection, perhaps via a proteolytic mechanism catalyzed by the endogenous 3C(pro) sequence.
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Affiliation(s)
- Aleksey G Aminev
- Institute for Molecular Virology, University of Wisconsin-Madison, Madison, WI 53706, USA.
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24
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Goodfellow IG, Polacek C, Andino R, Evans DJ. The poliovirus 2C cis-acting replication element-mediated uridylylation of VPg is not required for synthesis of negative-sense genomes. J Gen Virol 2003; 84:2359-2363. [PMID: 12917456 DOI: 10.1099/vir.0.19132-0] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nucleotides in the terminal loop of the poliovirus 2C cis-acting replication element (2C(CRE)), a 61 nt structured RNA, function as the template for the addition of two uridylate (U) residues to the viral protein VPg. This uridylylation reaction leads to the formation of VPgpUpU, which is used by the viral RNA polymerase as a nucleotide-peptide primer for genome replication. Although VPg primes both positive- and negative-strand replication, the specific requirement for 2C(CRE)-mediated uridylylation for one or both events has not been demonstrated. We have used a cell-free in vitro translation and replication reaction to demonstrate that 2C(CRE) is not required for the initiation of the negative-sense strand, which is synthesized in the absence of 2C(CRE)-mediated VPgpUpU formation. We propose that the 3' poly(A) tail could serve as the template for the formation of a VPg-poly(U) primer that functions in the initiation of negative-sense strands.
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Affiliation(s)
- Ian G Goodfellow
- Division of Virology, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow G11 5JR, UK
| | - Charlotta Polacek
- University of California San Francisco, Genentech Hall, San Francisco, CA 94143-2280, USA
| | - Raul Andino
- University of California San Francisco, Genentech Hall, San Francisco, CA 94143-2280, USA
| | - David J Evans
- Division of Virology, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow G11 5JR, UK
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25
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Binder JJ, Hoffman MA, Palmenberg AC. Genetic stability of attenuated mengovirus vectors with duplicate primary cleavage sequences. Virology 2003; 312:481-94. [PMID: 12919752 DOI: 10.1016/s0042-6822(03)00245-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Short poly(C)-tract Mengoviruses have proven vaccine efficacy in many species of animals. A novel vector for the delivery of foreign proteins was created by insertion of a second autoproteolytic primary cleavage cassette linked to a multiple cloning site (MCS) into an attenuated variant of Mengo. Nineteen cDNAs from foreign sequences that ranged from 39 to 1653 bases were cloned into the MCS. The viral reading frame was maintained and translation resulted in dual, autocatalytic excision of the foreign peptides without disruption of any Mengo proteins. All cDNAs except those with the largest insertions produced viable virus. Active proteins such as GFP, CAT, and SIV p27 were expressed within infected cells. Relative to parental Mengo, the growth kinetics and genetic stability of each vector was inversely proportional to the size of the inserted sequence. While segments up to 1000 bases could be carried, inserts greater than 500-600 bases were usually reduced in size during serial passage. The limit on carrying capacity was probably due to difficulties in virion assembly or particle stability. Yet for inserts less than 500-600 bases, the Mengo vectors provided an effective system for the delivery of foreign epitopes into cells and mice.
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Affiliation(s)
- J J Binder
- Institute for Molecular Virology, University of Wisconsin-Madison, Madison 53706, USA
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26
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Abstract
Current understanding of the molecular basis of pathogenesis of foot-and-mouth disease (FMD) has been achieved through over 100 years of study into the biology of the etiologic agent, FMDV. Over the last 40 years, classical biochemical and physical analyses of FMDV grown in cell culture have helped to reveal the structure and function of the viral proteins, while knowledge gained by the study of the virus' genetic diversity has helped define structures that are essential for replication and production of disease. More recently, the availability of genetic engineering methodology has permitted the direct testing of hypotheses formulated concerning the role of individual RNA structures, coding regions and polypeptides in viral replication and disease. All of these approaches have been aided by the simultaneous study of other picornavirus pathogens of animals and man, most notably poliovirus. Although many questions of how FMDV causes its devastating disease remain, the following review provides a summary of the current state of knowledge into the molecular basis of the virus' interaction with its host that produces one of the most contagious and frightening diseases of animals or man.
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Affiliation(s)
- Peter W Mason
- USDA, ARS Plum Island Animal Disease Center, ARS. PO Box 848, Greenport, NY 11944, USA.
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27
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Merkle I, van Ooij MJM, van Kuppeveld FJM, Glaudemans DHRF, Galama JMD, Henke A, Zell R, Melchers WJG. Biological significance of a human enterovirus B-specific RNA element in the 3' nontranslated region. J Virol 2002; 76:9900-9. [PMID: 12208967 PMCID: PMC136489 DOI: 10.1128/jvi.76.19.9900-9909.2002] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2002] [Accepted: 06/24/2002] [Indexed: 11/20/2022] Open
Abstract
The secondary structures predicted for the enteroviral 3' nontranslated region (3'NTR) all seem to indicate a conformation consisting of two (X and Y) hairpin structures. The higher-order RNA structure of the 3'NTR appears to exist as an intramolecular kissing interaction between the loops of these two hairpin structures. The enterovirus B-like subgroup possesses an additional stem-loop structure, domain Z, which is not present in the poliovirus-like enteroviruses. It has been suggested that the Z domain originated from a burst of short sequence repetitions (E. V. Pilipenko, S. V. Maslova, A. N. Sinyakov, and V. I. Agol, Nucleic Acids Res. 20:1739-1745, 1992). However, no functional features have yet been ascribed to this enterovirus B-like-specific RNA element in the 3'NTR. In this study, we tested the functional characteristics and biological significance of domain Z. A mutant of the cardiovirulent coxsackievirus group B3 strain Nancy which completely lacked the Z domain and which therefore acquired enterovirus C-like secondary structures exhibited a wild-type growth phenotype, as determined by single-cycle growth analysis with BGM cells. This result proves that the Z domain is virtually dispensable for viral growth in tissue cultures. Partial distortion of the Z domain structure resulted in a disabled virus with reduced growth kinetics, probably due to alternative conformations of the overall structure of the domain. Infection of mice showed that the recombinant coxsackievirus group B3 mutant which completely lacked the Z domain was less virulent. Pancreatic tissues from mice infected with wild-type virus and recombinant virus were equally affected. However, the heart tissue from mice infected with the recombinant virus showed only slight signs of myocarditis. These results suggest that the enterovirus B-like-specific Z domain plays a role in coxsackievirus-induced pathogenesis.
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Affiliation(s)
- Ingrid Merkle
- Institute of Virology, Friedrich Schiller University, D-07745 Jena, Germany
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28
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Witwer C, Rauscher S, Hofacker IL, Stadler PF. Conserved RNA secondary structures in Picornaviridae genomes. Nucleic Acids Res 2001; 29:5079-89. [PMID: 11812840 PMCID: PMC97546 DOI: 10.1093/nar/29.24.5079] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The family Picornaviridae contains important pathogens including, for example, hepatitis A virus and foot-and-mouth disease virus. The genome of these viruses is a single messenger-active (+)-RNA of 7200-8500 nt. Besides coding for the viral proteins, it also contains functionally important RNA secondary structures, among them an internal ribosomal entry site (IRES) region towards the 5'-end. This contribution provides a comprehensive computational survey of the complete genomic RNAs and a detailed comparative analysis of the conserved structural elements in seven of the currently nine genera in the family PICORNAVIRIDAE: Compared with previous studies we find: (i) that only smaller sections of the IRES region than previously reported are conserved at single base-pair resolution and (ii) that there is a number of significant structural elements in the coding region. Furthermore, we identify potential cis-acting replication elements in four genera where this feature has not been reported so far.
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Affiliation(s)
- C Witwer
- Institut für Theoretische Chemie und Molekulare Strukturbiologie, Universität Wien, Währingerstrasse 17, A-1090 Wien, Austria
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