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Li H, Song J, Deng Z, Yao Y, Qiao W, Tan J. Cleavage of Stau2 by 3C protease promotes EV-A71 replication. Virol J 2024; 21:216. [PMID: 39272111 PMCID: PMC11401396 DOI: 10.1186/s12985-024-02489-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2024] [Accepted: 09/04/2024] [Indexed: 09/15/2024] Open
Abstract
BACKGROUND Enterovirus A71 (EV-A71), as a neurotropic virus, mainly affects infants and young children under the age of 5. EV-A71 infection causes hand-foot-mouth disease and herpetic angina, and even life-threatening neurological complications. However, the molecular mechanism by which EV-A71 induces nervous system damage remains elusive. The viral protease 3C plays an important role during EV-A71 infection and is also a key intersection of virus-host interactions. Previously, we used yeast two-hybrid to screen out the host protein Double-stranded RNA-binding protein Staufen homolog 2 (Stau2), an important member involved in neuronal mRNA transport, potentially interacts with 3C. METHODS We used coimmunoprecipitation (Co-IP) and immunofluorescence assay (IFA) to confirm that EV-A71 3C interacts with Stau2. By constructing the mutant of Stau2, we found the specific site where the 3C protease cleaves Stau2. Detection of VP1 protein using Western blotting characterized EV-A71 viral replication, and overexpression or knockdown of Stau2 exhibited effects on EV-A71 replication. The effect of different cleavage products on EV-A71 replication was demonstrated by constructing Stau2 truncates. RESULTS In this study, we found that EV-A71 3C interacts with Stau2. Stau2 is cleaved by 3C at the Q507-G508 site. Overexpression of Stau2 promotes EV-A71 VP1 protein expression, whereas depletion of Stau2 by small interfering RNA inhibits EV-A71 replication. Stau2 is essential for EV-A71 replication, and the product of Stau2 cleavage by 3C, 508-570 aa, has activity that promotes EV-A71 replication. In addition, we found that mouse Stau2 is also cleaved by EV-A71 3C at the same site. CONCLUSIONS Our research provides an example for EV-A71-host interaction, enriching key targets of host factors that contribute to viral replication.
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Affiliation(s)
- Hui Li
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China
- Precision Medicine Center, Tianjin Medical University General Hospital, Tianjin, 300052, China
| | - Jie Song
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Zhi Deng
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Yunfang Yao
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Wentao Qiao
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Juan Tan
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, 300071, China.
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Mondal S, Sarvari G, Boehr DD. Picornavirus 3C Proteins Intervene in Host Cell Processes through Proteolysis and Interactions with RNA. Viruses 2023; 15:2413. [PMID: 38140654 PMCID: PMC10747604 DOI: 10.3390/v15122413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2023] [Revised: 12/07/2023] [Accepted: 12/09/2023] [Indexed: 12/24/2023] Open
Abstract
The Picornaviridae family comprises a large group of non-enveloped viruses with enormous impact on human and animal health. The picornaviral genome contains one open reading frame encoding a single polyprotein that can be processed by viral proteases. The picornaviral 3C proteases share similar three-dimensional structures and play a significant role in the viral life cycle and virus-host interactions. Picornaviral 3C proteins also have conserved RNA-binding activities that contribute to the assembly of the viral RNA replication complex. The 3C protease is important for regulating the host cell response through the cleavage of critical host cell proteins, acting to selectively 'hijack' host factors involved in gene expression, promoting picornavirus replication, and inactivating key factors in innate immunity signaling pathways. The protease and RNA-binding activities of 3C are involved in viral polyprotein processing and the initiation of viral RNA synthesis. Most importantly, 3C modifies critical molecules in host organelles and maintains virus infection by subtly subverting host cell death through the blocking of transcription, translation, and nucleocytoplasmic trafficking to modulate cell physiology for viral replication. Here, we discuss the molecular mechanisms through which 3C mediates physiological processes involved in promoting virus infection, replication, and release.
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Affiliation(s)
| | | | - David D. Boehr
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
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3
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Jagdeo JM, Dufour A, Klein T, Solis N, Kleifeld O, Kizhakkedathu J, Luo H, Overall CM, Jan E. N-Terminomics TAILS Identifies Host Cell Substrates of Poliovirus and Coxsackievirus B3 3C Proteinases That Modulate Virus Infection. J Virol 2018; 92:e02211-17. [PMID: 29437971 PMCID: PMC5874412 DOI: 10.1128/jvi.02211-17] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 01/26/2018] [Indexed: 12/19/2022] Open
Abstract
Enteroviruses encode proteinases that are essential for processing of the translated viral polyprotein. In addition, viral proteinases also target host proteins to manipulate cellular processes and evade innate antiviral responses to promote replication and infection. Although some host protein substrates of enterovirus proteinases have been identified, the full repertoire of targets remains unknown. We used a novel quantitative in vitro proteomics-based approach, termed terminal amine isotopic labeling of substrates (TAILS), to identify with high confidence 72 and 34 new host protein targets of poliovirus and coxsackievirus B3 (CVB3) 3C proteinases (3Cpros) in HeLa cell and cardiomyocyte HL-1 cell lysates, respectively. We validated a subset of candidate substrates that are targets of poliovirus 3Cproin vitro including three common protein targets, phosphoribosylformylglycinamidine synthetase (PFAS), hnRNP K, and hnRNP M, of both proteinases. 3Cpro-targeted substrates were also cleaved in virus-infected cells but not noncleavable mutant proteins designed from the TAILS-identified cleavage sites. Knockdown of TAILS-identified target proteins modulated infection both negatively and positively, suggesting that cleavage by 3Cpro promotes infection. Indeed, expression of a cleavage-resistant mutant form of the endoplasmic reticulum (ER)-Golgi vesicle-tethering protein p115 decreased viral replication and yield. As the first comprehensive study to identify and validate functional enterovirus 3Cpro substrates in vivo, we conclude that N-terminomics by TAILS is an effective strategy to identify host targets of viral proteinases in a nonbiased manner.IMPORTANCE Enteroviruses are positive-strand RNA viruses that encode proteases that cleave the viral polyprotein into the individual mature viral proteins. In addition, viral proteases target host proteins in order to modulate cellular pathways and block antiviral responses in order to facilitate virus infection. Although several host protein targets have been identified, the entire list of proteins that are targeted is not known. In this study, we used a novel unbiased proteomics approach to identify ∼100 novel host targets of the enterovirus 3C protease, thus providing further insights into the network of cellular pathways that are modulated to promote virus infection.
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Affiliation(s)
- Julienne M Jagdeo
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
- Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Antoine Dufour
- Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
- Centre for Blood Research, Faculty of Dentistry, Department of Oral Biological and Medical Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Theo Klein
- Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
- Centre for Blood Research, Faculty of Dentistry, Department of Oral Biological and Medical Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Nestor Solis
- Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
- Centre for Blood Research, Faculty of Dentistry, Department of Oral Biological and Medical Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Oded Kleifeld
- School of Biomedical Sciences, Monash University, Victoria, Australia
| | - Jayachandran Kizhakkedathu
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Honglin Luo
- Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Christopher M Overall
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
- Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
- Centre for Blood Research, Faculty of Dentistry, Department of Oral Biological and Medical Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Eric Jan
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
- Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
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4
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Li J, Yao Y, Chen Y, Xu X, Lin Y, Yang Z, Qiao W, Tan J. Enterovirus 71 3C Promotes Apoptosis through Cleavage of PinX1, a Telomere Binding Protein. J Virol 2017; 91:e02016-16. [PMID: 27847364 PMCID: PMC5215332 DOI: 10.1128/jvi.02016-16] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 11/01/2016] [Indexed: 12/20/2022] Open
Abstract
Enterovirus 71 (EV71) is an emerging pathogen causing hand, foot, and mouth disease (HFMD) and fatal neurological diseases in infants and young children due to their underdeveloped immunocompetence. EV71 infection can induce cellular apoptosis through a variety of pathways, which promotes EV71 release. The viral protease 3C plays an important role in EV71-induced apoptosis. However, the molecular mechanism responsible for 3C-triggered apoptosis remains elusive. Here, we found that EV71 3C directly interacted with PinX1, a telomere binding protein. Furthermore, 3C cleaved PinX1 at the site of Q50-G51 pair through its protease activity. Overexpression of PinX1 reduced the level of EV71-induced apoptosis and EV71 release, whereas depletion of PinX1 by small interfering RNA promoted apoptosis induced by etoposide and increased EV71 release. Taken together, our study uncovered a mechanism that EV71 utilizes to promote host cell apoptosis through cleavage of cellular protein PinX1 by 3C. IMPORTANCE EV71 3C plays an important role in processing viral proteins and interacting with host cells. In this study, we showed that 3C promoted apoptosis through cleaving PinX1, a telomere binding protein, and that this cleavage facilitated EV71 release. Our study demonstrated that PinX1 plays an important role in EV71 release and revealed a novel mechanism that EV71 utilizes to induce apoptosis. This finding is important in understanding EV71-host cell interactions and has potential impact on understanding other enterovirus-host cell interactions.
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Affiliation(s)
- Jing Li
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Yunfang Yao
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Yu Chen
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Xiao Xu
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Yongquan Lin
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Zhilong Yang
- Division of Biology, Kansas State University, Manhattan, Kansas, USA
| | - Wentao Qiao
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
| | - Juan Tan
- Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin, China
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5
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Banerjee R, Weidman MK, Navarro S, Comai L, Dasgupta A. Modifications of both selectivity factor and upstream binding factor contribute to poliovirus-mediated inhibition of RNA polymerase I transcription. J Gen Virol 2005; 86:2315-2322. [PMID: 16033979 DOI: 10.1099/vir.0.80817-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Soon after infection, poliovirus (PV) shuts off host-cell transcription, which is catalysed by all three cellular RNA polymerases. rRNA constitutes more than 50 % of all cellular RNA and is transcribed from rDNA by RNA polymerase I (pol I). Here, evidence has been provided suggesting that both pol I transcription factors, SL-1 (selectivity factor) and UBF (upstream binding factor), are modified and inactivated in PV-infected cells. The viral protease 3C(pro) appeared to cleave the TATA-binding protein-associated factor 110 (TAF(110)), a subunit of the SL-1 complex, into four fragments in vitro. In vitro protease-cleavage assays using various mutants of TAF(110) and purified 3C(pro) indicated that the Q(265)G(266) and Q(805)G(806) sites were cleaved by 3C(pro). Both SL-1 and UBF were depleted in PV-infected cells and their disappearance correlated with pol I transcription inhibition. rRNA synthesis from a template containing a human pol I promoter demonstrated that both SL-1 and UBF were necessary to restore pol I transcription fully in PV-infected cell extracts. These results suggested that both SL-1 and UBF are transcriptionally inactivated in PV-infected HeLa cells.
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Affiliation(s)
- Rajeev Banerjee
- Department of Microbiology, Immunology and Molecular Genetics, University of California Los Angeles, UCLA School of Medicine, 10833 Le Conte Avenue, Los Angeles, CA 90095, USA
| | - Mary K Weidman
- Department of Microbiology, Immunology and Molecular Genetics, University of California Los Angeles, UCLA School of Medicine, 10833 Le Conte Avenue, Los Angeles, CA 90095, USA
| | - Sonia Navarro
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
| | - Lucio Comai
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
| | - Asim Dasgupta
- Department of Microbiology, Immunology and Molecular Genetics, University of California Los Angeles, UCLA School of Medicine, 10833 Le Conte Avenue, Los Angeles, CA 90095, USA
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6
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Kundu P, Raychaudhuri S, Tsai W, Dasgupta A. Shutoff of RNA polymerase II transcription by poliovirus involves 3C protease-mediated cleavage of the TATA-binding protein at an alternative site: incomplete shutoff of transcription interferes with efficient viral replication. J Virol 2005; 79:9702-13. [PMID: 16014932 PMCID: PMC1181600 DOI: 10.1128/jvi.79.15.9702-9713.2005] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2004] [Accepted: 04/24/2005] [Indexed: 11/20/2022] Open
Abstract
The TATA-binding protein (TBP) plays a crucial role in cellular transcription catalyzed by all three DNA-dependent RNA polymerases. Previous studies have shown that TBP is targeted by the poliovirus (PV)-encoded protease 3C(pro) to bring about shutoff of cellular RNA polymerase II-mediated transcription in PV-infected cells. The processing of the majority of viral precursor proteins by 3C(pro) involves cleavages at glutamine-glycine (Q-G) sites. We present evidence that suggests that the transcriptional inactivation of TBP by 3C(pro) involves cleavage at the glutamine 104-serine 105 (Q104-S105) site of TBP and not at the Q18-G19 site as previously thought. The TBP Q104-S105 cleavage by 3C(pro) is greatly influenced by the presence of an aliphatic amino acid at the P4 position, a hallmark of 3C(pro)-mediated proteolysis. To examine the importance of host cell transcription shutoff in the PV life cycle, stable HeLa cell lines were created that express recombinant TBP resistant to cleavage by the viral proteases, called GG rTBP. Transcription shutoff was significantly impaired and delayed in GG rTBP cells upon infection with poliovirus compared with the cells that express wild-type recombinant TBP (wt rTBP). Infection of GG rTBP cells with poliovirus resulted in small plaques, significantly reduced viral RNA synthesis, and lower viral yields compared to the wt rTBP cell line. These results suggest that a defect in transcription shutoff can lead to inefficient replication of poliovirus in cultured cells.
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Affiliation(s)
- Pallob Kundu
- Department of Microbiology, Immunology, and Molecular Genetics, UCLA School of Medicine, University of California--Los Angeles, 90095, USA
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7
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Back SH, Kim YK, Kim WJ, Cho S, Oh HR, Kim JE, Jang SK. Translation of polioviral mRNA is inhibited by cleavage of polypyrimidine tract-binding proteins executed by polioviral 3C(pro). J Virol 2002; 76:2529-42. [PMID: 11836431 PMCID: PMC135932 DOI: 10.1128/jvi.76.5.2529-2542.2002] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2001] [Accepted: 12/04/2001] [Indexed: 12/26/2022] Open
Abstract
The translation of polioviral mRNA occurs through an internal ribosomal entry site (IRES). Several RNA-binding proteins, such as polypyrimidine tract-binding protein (PTB) and poly(rC)-binding protein (PCBP), are required for the poliovirus IRES-dependent translation. Here we report that a poliovirus protein, 3C(pro) (and/or 3CD(pro)), cleaves PTB isoforms (PTB1, PTB2, and PTB4). Three 3C(pro) target sites (one major target site and two minor target sites) exist in PTBs. PTB fragments generated by poliovirus infection are redistributed to the cytoplasm from the nucleus, where most of the intact PTBs are localized. Moreover, these PTB fragments inhibit polioviral IRES-dependent translation in a cell-based assay system. We speculate that the proteolytic cleavage of PTBs may contribute to the molecular switching from translation to replication of polioviral RNA.
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Affiliation(s)
- Sung Hoon Back
- NRL, Department of Life Science, Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang, Kyungbuk 790-784, Korea
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8
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Li ML, Hsu TA, Chen TC, Chang SC, Lee JC, Chen CC, Stollar V, Shih SR. The 3C protease activity of enterovirus 71 induces human neural cell apoptosis. Virology 2002; 293:386-95. [PMID: 11886259 DOI: 10.1006/viro.2001.1310] [Citation(s) in RCA: 139] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The human glioblastoma SF268 cell line was used to investigate the induction of apoptosis by the 3C protease of enterovirus 71 (EV71). Transient expression in these cells of the wild-type 3C protein encoded by EV71 induced morphological alterations typical of apoptosis, including generation of apoptotic bodies. Degradation of cellular DNA in nucleosomes was also observed. When two of the amino acids in the catalytic motif of 3C were changed by mutagenesis, the 3C protein not only lost its proteolytic activity, but also its ability to induce apoptosis in the SF268 cells. Twenty-four hours after 3C transfection, poly(ADP-ribose) polymerase, a DNA repair enzyme, was cleaved, indicating that caspases were activated by the expression of EV71 3C. The 3C-induced apoptosis was blocked by the caspase inhibitors DEVD-fmk and VAD-fmk. Our findings suggest that the proteolytic activity of 3C triggers apoptosis in the SF268 cells through a mechanism involving caspase activation and that this apoptotic pathway may play an important role in the pathogenesis of EV71 infection.
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Affiliation(s)
- Mei-Ling Li
- School of Medical Technology, Chang Gung University, Tao-Yuan, Taiwan
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9
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Mosimann SC, Cherney MM, Sia S, Plotch S, James MN. Refined X-ray crystallographic structure of the poliovirus 3C gene product. J Mol Biol 1997; 273:1032-47. [PMID: 9367789 DOI: 10.1006/jmbi.1997.1306] [Citation(s) in RCA: 149] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The X-ray crystallographic structure of the recombinant poliovirus 3C gene product (Mahoney strain) has been determined by single isomorphous replacement and non-crystallographic symmetry averaging and refined at 2.1 A resolution. Poliovirus 3C is comprised of two six-stranded antiparallel beta-barrel domains and is structurally similar to the chymotrypsin-like serine proteinases. The shallow active site cleft is located at the junction of the two beta-barrel domains and contains a His40, Glu71, Cys147 catalytic triad. The polypeptide loop preceding Cys147 is flexible and likely undergoes a conformational change upon substrate binding. The specificity pockets for poliovirus 3C are well-defined and modeling studies account for the known substrate specificity of this proteinase. Poliovirus 3C also participates in the formation of the viral replicative initiation complex where it specifically recognizes and binds the RNA stem-loop structure in the 5' non-translated region of its own genome. The RNA recognition site of 3C is located on the opposite side of the molecule in relation to its proteolytic active site and is centered about the conserved KFRDIR sequence of the domain linker. The recognition site is well-defined and also includes residues from the amino and carboxy-terminal helices. The two molecules in the asymmetric unit are related by an approximate 2-fold, non-crystallographic symmetry and form an intermolecular antiparallel beta-sheet at their interface.
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Affiliation(s)
- S C Mosimann
- Medical Research Council of Canada Group in Protein Structure and Function Department of Biochemistry, University of Alberta, Edmonton, AB, T6G 2H7, Canada
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10
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van Kuppeveld FJ, van den Hurk PJ, Zoll J, Galama JM, Melchers WJ. Mutagenesis of the coxsackie B3 virus 2B/2C cleavage site: determinants of processing efficiency and effects on viral replication. J Virol 1996; 70:7632-40. [PMID: 8892883 PMCID: PMC190832 DOI: 10.1128/jvi.70.11.7632-7640.1996] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The enterovirus 2B/2C cleavage site differs from the common cleavage site motif AxxQ/G by the occurrence of either polar residues at the P1' position or large aliphatic residues at the P4 position. To study (i) the putative contribution of these aberrant residues to the stability of precursor protein 2BC, (ii) the determinants of cleavage site specificity and efficiency of 3Cpro, and (iii) the importance of efficient cleavage at this site for viral replication, a mutational analysis of the coxsackie B3 virus (CBV3) 2B/2C cleavage site (AxxQ/N) was performed. Neither replacement of the P1' asparagine with a serine or a glycine nor replacement of the P4 alanine with a valine significantly affected 2B/2C cleavage efficiency, RNA replication, or virus growth. The introduction of a P4 asparagine, as can be found at the CBV3 3C/3D cleavage site, caused a severe reduction in 2B/2C cleavage and abolished virus growth. These data support the idea that a P4 asparagine is an unfavorable residue that contributes to a slow turnover of precursor protein 3CD but argue that it is unlikely that the aberrant 2B/2C cleavage site motifs serve to regulate 2B/2C processing efficiency and protein 2BC stability. The viability of a double mutant containing a P4 asparagine and a P1' glycine demonstrated that a P1' residue can compensate for the adverse effects of an unfavorable P4 residue. Poliovirus (or poliovirus-like) 2B/2C cleavage site motifs were correctly processed by CBV 3Cpro, albeit with a reduced efficiency, and yielded viable viruses. Analysis of in vivo protein synthesis showed that mutant viruses containing poorly processed 2B/2C cleavage sites were unable to completely shut off cellular protein synthesis. The failure to inhibit host translation coincided with a reduced ability to modify membrane permeability, as measured by the sensitivity to the unpermeant translation inhibitor hygromycin B. These data suggest that a critical level of protein 2B or 2C, or both, may be required to alter membrane permeability and, possibly as a consequence, to shut off host cell translation.
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Affiliation(s)
- F J van Kuppeveld
- Department of Medical Microbiology, University of Nijmegen, The Netherlands.
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11
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Ansardi DC, Porter DC, Anderson MJ, Morrow CD. Poliovirus Assembly and Encapsidation of Genomic RNA. Adv Virus Res 1996. [DOI: 10.1016/s0065-3527(08)60069-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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12
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Abstract
The 3C proteinases are a novel group of cysteine proteinases with a serine proteinase-like fold that are responsible for the bulk of polyprotein processing in the Picornaviridae. Because members of this viral family are to blame for several ongoing global pandemic problems (rhinovirus, hepatitis A virus) as well as sporadic outbreaks of more serious pathologies (poliovirus), there has been continuing interest over the last two decades in the development of antiviral therapies. The recent determination of the structure of two of the 3C proteinases by X-ray crystallography opens the door for the application of the latest advances in computer-assisted identification and design of anti-proteinase therapeutic/chemoprophylactic agents.
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Affiliation(s)
- B A Malcolm
- Department of Biochemistry, University of Alberta, Edmonton, Canada
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13
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Affiliation(s)
- T Skern
- Department of Biochemistry, Medical Faculty, University of Vienna, Austria
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14
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Abstract
This chapter presents families of cysteine peptidases. The activity of all cysteine peptidases depends on a catalytic dyad of cysteine and histidine. The order of the cysteine and histidine residues (Cys/His or His/Cys) in the linear sequence differs between families and this is among the lines of evidence suggesting that cysteine peptidases have had many separate evolutionary origins. The families C1, C2, and C10 can be described as “papainlike,” and form clan CA. The papain family contains peptidases with a wide variety of activities, including endopeptidases with broad specificity, endopeptidases with narrow specificity, aminopeptidases, and peptidases with both endopeptidase and exopeptidase activities. Papain homologs are generally either lysosomal or secreted proteins. The calpain family includes the calcium-dependent cytosolic endopeptidase calpain, which is known from birds and mammals, and the product of the sol gene in Drosophila. Calpain is a complex of two peptide chains. Picornains are a family of polyprotein-processing endopeptidases from single-stranded RNA viruses. Each picornavirus has two picornains (2A and 3C).
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Affiliation(s)
- N D Rawlings
- Strangeways Research Laboratory, Cambridge, United Kingdom
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15
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Ansardi DC, Morrow CD. Poliovirus capsid proteins derived from P1 precursors with glutamine-valine cleavage sites have defects in assembly and RNA encapsidation. J Virol 1993; 67:7284-97. [PMID: 8230452 PMCID: PMC238192 DOI: 10.1128/jvi.67.12.7284-7297.1993] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Assembly of poliovirus virions requires proteolytic cleavage of the P1 capsid precursor polyprotein between two separate glutamine-glycine (QG) amino acid pairs by the viral protease 3CD. In this study, we have investigated the effects on P1 polyprotein processing and subsequent assembly of processed capsid proteins caused by substitution of the glycine residue at the individual QG cleavage sites with valine (QG-->QV). P1 cDNAs encoding the valine substitutions were created by site-directed mutagenesis and were recombined into wild-type vaccinia virus to generate recombinant vaccinia viruses which expressed the mutant P1 precursors. The recombinant vaccinia virus-expressed mutant P1 polyproteins were analyzed for proteolytic processing defects in cells coinfected with a recombinant vaccinia virus (VVP3) that expresses the poliovirus 3CD protease and for processing and assembly defects by using a trans complementation system in which P1-expressing recombinant vaccinia viruses provide capsid precursor to a defective poliovirus genome that does not express functional capsid proteins (D. C. Ansardi, D. C. Porter, and C. D. Morrow, J. Virol. 67:3684-3690, 1993). The QV-substituted precursors were proteolytically processed at the altered sites both in cells coinfected with VVP3 and in cells coinfected with defective poliovirus, although the kinetics of cleavage at the altered sites were slower than those of cleavage at the wild-type QG site in the precursor. Completely processed capsid proteins VP0, VP3, and VP1 derived from the mutant precursor containing a valine at the amino terminus of VP3 (VP3-G001V) were unstable and failed to assemble stable subviral structures in cells coinfected with defective poliovirus. In contrast, capsid proteins derived from the P1 precursor with a valine substitution at the amino terminus of VP1 (VP1-G001V) assembled empty capsid particles but were deficient in assembling RNA-containing virions. The assembly characteristics of the VP1-G001V mutant were compared with those of a previously described VP3-VP1 cleavage site mutant (K. Kirkegaard and B. Nelsen, J. Virol. 64:185-194, 1990) which contained a deletion of the first four amino-terminal residues of VP1 (VP1-delta 1-4) and which was reconstructed for our studies into the recombinant vaccinia virus system. Complete proteolytic processing of the VP1-delta 1-4 precursor also occurred more slowly than complete cleavage of the wild-type precursor, and formation of virions was delayed; however, capsid proteins derived from the VP1-G001V mutant assembled RNA-containing virions less efficiently than those derived from the VP1-delta 1-4 precursor.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- D C Ansardi
- Department of Microbiology, University of Alabama at Birmingham 35294-0007
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16
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Dougherty WG, Semler BL. Expression of virus-encoded proteinases: functional and structural similarities with cellular enzymes. Microbiol Rev 1993; 57:781-822. [PMID: 8302216 PMCID: PMC372939 DOI: 10.1128/mr.57.4.781-822.1993] [Citation(s) in RCA: 198] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Many viruses express their genome, or part of their genome, initially as a polyprotein precursor that undergoes proteolytic processing. Molecular genetic analyses of viral gene expression have revealed that many of these processing events are mediated by virus-encoded proteinases. Biochemical activity studies and structural analyses of these viral enzymes reveal that they have remarkable similarities to cellular proteinases. However, the viral proteinases have evolved unique features that permit them to function in a cellular environment. In this article, the current status of plant and animal virus proteinases is described along with their role in the viral replication cycle. The reactions catalyzed by viral proteinases are not simple enzyme-substrate interactions; rather, the processing steps are highly regulated, are coordinated with other viral processes, and frequently involve the participation of other factors.
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Affiliation(s)
- W G Dougherty
- Department of Microbiology, Oregon State University, Corvallis 97331-3804
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17
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Scott NW, Cooper JI, Edwards ML. The identification, cloning, and sequence analysis of the coat protein coding region of a birch isolate (I2) of cherry leaf roll nepovirus. Arch Virol 1993; 131:209-15. [PMID: 8328915 DOI: 10.1007/bf01379093] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The coat protein gene of RNA-2 of cherry leaf roll nepovirus (CLRV) birch isolate I2 was cloned, identified, and sequenced. Transcripts derived from cDNA to the coat protein gene made a polypeptide of M(r) 51.5 k when translated in vitro. The predicted amino acid sequence of the coat protein showed little identity with nepoviruses having small RNA-2s. It did, however, have 27% sequence identity with the coat protein of tomato ringspot nepovirus which, like CLRV, has a relatively large RNA-2.
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Affiliation(s)
- N W Scott
- Institute of Virology and Environmental Microbiology, Oxford, U.K
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18
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Harris KS, Reddigari SR, Nicklin MJ, Hämmerle T, Wimmer E. Purification and characterization of poliovirus polypeptide 3CD, a proteinase and a precursor for RNA polymerase. J Virol 1992; 66:7481-9. [PMID: 1331532 PMCID: PMC240456 DOI: 10.1128/jvi.66.12.7481-7489.1992] [Citation(s) in RCA: 93] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
A cDNA clone encoding the 3CD proteinase (3CDpro) of poliovirus type 2 (Sabin), the precursor to proteinase 3Cpro and RNA polymerase 3Dpol, was expressed in bacteria by using a T7 expression system. Site-specific mutagenesis of the 3C/3D cleavage site was performed to generate active proteolytic precursors impaired in their ability to process themselves to 3Cpro and 3Dpol. Of these mutations, the exchange of the Thr residue at the P4 position of the 3C/3D cleavage site for a Lys residue (3CDpro T181K) resulted in a mutant polypeptide exhibiting the smallest amount of autoprocessing. This mutant was purified to 86% homogeneity and used for subsequent proteolytic studies. Purified 3CDproM (M designates the cleavage site mutant 3CDpro T181K) was capable of cleaving the P1 capsid precursor, a peptide representing the 2BC cleavage site, and the 2BC precursor polypeptide. Purified 3CDproM demonstrated the same detergent sensitivity in processing experiments with the capsid precursor as was observed by using P1 and crude extracts of poliovirus-infected HeLa cell lysates. Purified 3CDproM did not have any detectable RNA polymerase activity, whereas 3Dpol, separated from 3CDproM by gel filtration in the last step of purification, did. We conclude that 3CDproM can process both structural and nonstructural precursors of the poliovirus polyprotein and that it is active against a synthetic peptide substrate. Moreover, cleavage of 3CD to 3Dpol is needed to activate the 3D RNA polymerase.
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Affiliation(s)
- K S Harris
- Department of Microbiology, State University of New York, Stony Brook 11794-8621
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19
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Lawson MA, Semler BL. Alternate poliovirus nonstructural protein processing cascades generated by primary sites of 3C proteinase cleavage. Virology 1992; 191:309-20. [PMID: 1329322 DOI: 10.1016/0042-6822(92)90193-s] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The post-translational regulation of picornavirus gene expression mediated by the cascade processing of viral proteins is not well understood. Both pulse-chase studies of infected cells and in vitro studies of the translation of poliovirus type 1 RNA transcribed from genomic cDNA clones indicate a specific cascade of polyprotein processing in which the P1, P2, and P3 precursor proteins are primary products of viral proteinase cleavage. We report the results of a short-time kinetic analysis of poliovirus type 1 protein processing in an in vitro translation system and in infected HeLa cells which indicate the existence of another, rapid pathway of polyprotein processing mediated by the activity of the 3C proteinase. The observed pathway is distinct from and in addition to the one previously known. The potential role of this alternative pathway of processing in the post-translational regulation of viral gene expression is discussed.
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Affiliation(s)
- M A Lawson
- Department of Microbiology and Molecular Genetics, College of Medicine, University of California, Irvine 92717
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20
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Abstract
Poliovirus proteinase 2A (2Apro) is autocatalytically released from the viral polyprotein by cleavage in cis of a Tyr-Gly dipeptide at its own amino terminus, resulting in separation of the P1 structural and P2-P3 nonstructural protein precursors. A second Ty-Gly dipeptide within 3D polymerase is cleaved by 2Apro in trans, but this is not essential for viral proliferation. The mechanism which limits cleavage to only 2 of the 10 Tyr-Gly dipeptides within the poliovirus polyprotein has not been characterized. We have therefore undertaken a systematic mutational analysis of the VP1-2A site to elucidate determinants of substrate recognition by 2Apro. The P2 and P1' positions are important determinants for cis cleavage of this site, whereas a variety of substituents could be tolerated at the P2', P1, and P3 positions. The requirements for trans cleavage of this site were more stringent. We found that the 2Apro of coxsackievirus type A21 and rhinoviruses 2 and 14 have stringent requirements similar to those of poliovirus 2Apro for cleavage in trans.
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Affiliation(s)
- C U Hellen
- Department of Microbiology, State University of New York, Stony Brook 11794-8621
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21
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Abstract
Proteases are unquestionably the single most studied class of enzymes and yet many questions still remain about their mechanisms and roles. Protein engineering offers the opportunity to provide some of the answers. In this review, recent advances towards the understanding of stability, mechanism, specificity and regulation of proteases and their inhibitors are outlined. In addition, the application of this increased understanding is also discussed.
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Affiliation(s)
- A C Storer
- National Research Council, Biotechnology Research Institute, Montréal, Québec, Canada
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22
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Abstract
Research on the activity of self-cleaving proteases in bacterial, mammalian and virus-infected cells is reviewed, with an emphasis on the diversity of regulatory systems controlled by protein processing. Each of these three groups will be considered in turn by focusing on the following systems: the Rec A-dependent intramolecular cleavage of the Escherichia coli SOS response protein, LexA; the intramolecular activation of the mammalian aspartic acid protease, pepsinogen; and the autocatalytic cleavage of polyproteins synthesized by picornaviruses.
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Neufeld KL, Richards OC, Ehrenfeld E. Expression and characterization of poliovirus proteins 3BVPg, 3Cpro, and 3Dpol in recombinant baculovirus-infected Spodoptera frugiperda cells. Virus Res 1991; 19:173-88. [PMID: 1654015 DOI: 10.1016/0168-1702(91)90044-v] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
As an initial step toward investigating the roles of poliovirus proteins in viral RNA replication, a baculovirus expression system was used to produce poliovirus proteins from the P3 region. Spodoptera frugiperda (Sf9) cells were infected with a recombinant baculovirus, vETL-PoV3A*BCD, which contains cDNA coding for poliovirus proteins 3D, 3C, 3B, and a portion of 3A protein sequence. Immunofluorescence microscopy revealed that the majority of 3D (polymerase) was in the cytoplasm of recombinant baculovirus-infected Sf9 cells. In the same cells, the 3C (protease) and 3B (VPg) proteins appeared to be located in distinct subcellular regions, possibly membrane structures, suggesting that the expressed polyprotein was cleaved to generate mature proteins. Processing of the polypeptide was confirmed by immunoblot analysis which demonstrated that 3Cpro sequences were active in cleavage of the polyproteins 3A*BCD and 3CD. Over 95% of the 3D sequences accumulated in the form of mature 3Dpol, with only low levels of 3CD remaining. The majority of 3Dpol remained in the supernatant after low speed centrifugation of sonicated cells. The 3Dpol had RNA-dependent RNA polymerase activity as measured by elongation of an oligo(U) primer using a poly(A) template. The protein 3CDpro was active in cleaving P1 protein. The yield and activities of the poliovirus proteins expressed will facilitate future biochemical studies.
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Affiliation(s)
- K L Neufeld
- Department of Cellular Biology, University of Utah School of Medicine, Salt Lake City 84132
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Kean KM, Teterina NL, Marc D, Girard M. Analysis of putative active site residues of the poliovirus 3C protease. Virology 1991; 181:609-19. [PMID: 1849679 DOI: 10.1016/0042-6822(91)90894-h] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
It was recently suggested that the picornavirus 3C proteases are homologous to the chymotrypsin-like serine proteases. The two structural models proposed differ in one of the postulated active site residues, Glu/Asp71 or Asp85. We changed Glu71 of the poliovirus type 1 protease to Asp or Gln and Asp85 to Glu by oligonucleotide-directed site-specific mutagenesis of an infectious cDNA, and attempted to recover virus after transfection. Both Glu71 changes were lethal for the virus and proteolytic activity was abolished in vitro with the exception of the primary cleavage event at the P2/P3 junction. In contrast, the Asp85----Glu virus was viable. This mutant was temperature-sensitive for growth at 39 degrees and exhibited a minute plaque phenotype at permissive temperature. This defect correlated with low levels of viral-specific RNA and protein syntheses and slow virus growth. Proteolytic processing at the COOH-terminus of 3C was impaired, reducing the production of mature 3C and the viral replicase 3D. In addition, 3C-mediated cleavage events within the P2 region of the polyprotein seemed to occur rather inefficiently. 3C-specific processing within P1 and elsewhere within P3 was unaffected. We suggest that Asp85 does not form part of the active site of 3C, but could be important for the specific recognition of cleavage sites within P2.
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Affiliation(s)
- K M Kean
- Unité de Virologie Moléculaire (CNRS UA 545), Institut Pasteur, Paris, France
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