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Zheng Y, Li G, Luo Q, Sha H, Zhang H, Wang R, Kong W, Liao J, Zhao M. Research progress on the N protein of porcine reproductive and respiratory syndrome virus. Front Microbiol 2024; 15:1391697. [PMID: 38741730 PMCID: PMC11089252 DOI: 10.3389/fmicb.2024.1391697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Accepted: 04/08/2024] [Indexed: 05/16/2024] Open
Abstract
Porcine reproductive and respiratory syndrome (PRRS) is a highly contagious disease caused by the porcine reproductive and respiratory syndrome virus (PRRSV). PRRSV exhibits genetic diversity and complexity in terms of immune responses, posing challenges for eradication. The nucleocapsid (N) protein of PRRSV, an alkaline phosphoprotein, is important for various biological functions. This review summarizes the structural characteristics, genetic evolution, impact on PRRSV replication and virulence, interactions between viral and host proteins, modulation of host immunity, detection techniques targeting the N protein, and progress in vaccine development. The discussion provides a theoretical foundation for understanding the pathogenic mechanisms underlying PRRSV virulence, developing diagnostic techniques, and designing effective vaccines.
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Affiliation(s)
- Yajie Zheng
- School of Life Science and Engineering, Foshan University, Foshan, China
| | - Gan Li
- School of Life Science and Engineering, Foshan University, Foshan, China
| | - Qin Luo
- School of Life Science and Engineering, Foshan University, Foshan, China
| | - Huiyang Sha
- School of Life Science and Engineering, Foshan University, Foshan, China
| | - Hang Zhang
- School of Life Science and Engineering, Foshan University, Foshan, China
| | - Ruining Wang
- College of Veterinary Medicine, Henan University of Animal Husbandry and Economy, Zhengzhou, China
| | - Weili Kong
- Gladstone Institutes of Virology and Immunology, University of California, San Francisco, San Francisco, CA, United States
| | - Jiedan Liao
- School of Life Science and Engineering, Foshan University, Foshan, China
| | - Mengmeng Zhao
- School of Life Science and Engineering, Foshan University, Foshan, China
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Zheng J, Li N, Li X, Han Y, Lv X, Zhang H, Ren L. The Nuclear Localization Signal of Porcine Circovirus Type 4 Affects the Subcellular Localization of the Virus Capsid and the Production of Virus-like Particles. Int J Mol Sci 2024; 25:2459. [PMID: 38473709 DOI: 10.3390/ijms25052459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 01/29/2024] [Accepted: 02/18/2024] [Indexed: 03/14/2024] Open
Abstract
Porcine circovirus 4 (PCV4) is a newly identified virus belonging to PCV of the Circoviridae family, the Circovirus genus. We previously found that PCV4 is pathogenic in vitro, while the virus's replication in cells is still unknown. In this study, we evaluated the N-terminal of the PCV4 capsid (Cap) and identified an NLS at amino acid residues 4-37 of the N-terminus of the PCV4 Cap, 4RSRYSRRRRNRRNQRRRGLWPRASRRRYRWRRKN37. The NLS was further divided into two fragments (NLS-A and NLS-B) based on the predicted structure, including two α-helixes, which were located at 4RSRYSRRRRNRRNQRR19 and 24PRASRRRYRWRRK36, respectively. Further studies showed that the NLS, especially the first α-helixes formed by the NLS-A fragment, determined the nuclear localization of the Cap protein, and the amino acid 4RSRY7 in the NLS of the PCV4 Cap was the critical motif affecting the VLP packaging. These results will provide a theoretical basis for elucidating the infection mechanism of PCV4 and developing subunit vaccines based on VLPs.
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Affiliation(s)
- Jiawei Zheng
- College of Animal Sciences, Key Lab for Zoonoses Research, Ministry of Education, Jilin University, 5333 Xi'an Road, Changchun 130062, China
| | - Nan Li
- Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, 666 Liuying West Road, Changchun 130122, China
| | - Xue Li
- College of Animal Sciences, Key Lab for Zoonoses Research, Ministry of Education, Jilin University, 5333 Xi'an Road, Changchun 130062, China
| | - Yaqi Han
- College of Animal Sciences, Key Lab for Zoonoses Research, Ministry of Education, Jilin University, 5333 Xi'an Road, Changchun 130062, China
| | - Xinru Lv
- College of Animal Sciences, Key Lab for Zoonoses Research, Ministry of Education, Jilin University, 5333 Xi'an Road, Changchun 130062, China
| | - Huimin Zhang
- College of Animal Sciences, Key Lab for Zoonoses Research, Ministry of Education, Jilin University, 5333 Xi'an Road, Changchun 130062, China
| | - Linzhu Ren
- College of Animal Sciences, Key Lab for Zoonoses Research, Ministry of Education, Jilin University, 5333 Xi'an Road, Changchun 130062, China
- College of Veterinary Medicine, Yunnan Agricultural University, Kunming 650201, China
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Zhang A, Sun Y, Jing H, Liu J, Duan E, Ke W, Tao R, Li Y, Wang J, Cao S, Zhao P, Wang H, Zhang Y. Interaction of HnRNP F with the guanine-rich segments in viral antigenomic RNA enhances porcine reproductive and respiratory syndrome virus-2 replication. Virol J 2022; 19:82. [PMID: 35570267 PMCID: PMC9107676 DOI: 10.1186/s12985-022-01811-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Accepted: 05/05/2022] [Indexed: 11/12/2022] Open
Abstract
Background Heterogeneous nuclear ribonucleoprotein (HnRNP) F is a member of HnRNP family proteins that participate in splicing of cellular newly synthesized mRNAs by specifically recognizing tandem guanine-tracts (G-tracts) RNA sequences. Whether HnRNP F could recognize viral-derived tandem G-tracts and affect virus replication remain poorly defined. Methods The effect of HnRNP F on porcine reproductive and respiratory syndrome virus (PRRSV) propagation was evaluated by real-time PCR, western blotting, and plaque-forming unit assay. The association between HnRNP F and PRRSV guanine-rich segments (GRS) were analyzed by RNA pulldown and RNA immunoprecipitation. The expression pattern of HnRNP F was investigated by western blotting and nuclear and cytoplasmic fractionation. Results Knockdown of endogenous HnRNP F effectively blocks the synthesis of viral RNA and nucleocapsid (N) protein. Conversely, overexpression of porcine HnRNP F has the opposite effect. Moreover, RNA pulldown and RNA immunoprecipitation assays reveal that the qRMM1 and qRRM2 domains of HnRNP F recognize the GRS in PRRSV antigenomic RNA. Finally, HnRNP F is redistributed into the cytoplasm and forms a complex with guanine-quadruplex (G4) helicase DHX36 during PRRSV infection. Conclusions These findings elucidate the potential functions of HnRNP F in regulating the proliferation of PRRSV and contribute to a better molecular understanding of host-PRRSV interactions.
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Zhao P, Jing H, Dong W, Duan E, Ke W, Tao R, Li Y, Cao S, Wang H, Zhang Y, Sun Y, Wang J. TRIM26-mediated degradation of nucleocapsid protein limits porcine reproductive and respiratory syndrome virus-2 infection. Virus Res 2022; 311:198690. [PMID: 35077707 DOI: 10.1016/j.virusres.2022.198690] [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: 09/15/2021] [Revised: 01/17/2022] [Accepted: 01/20/2022] [Indexed: 11/16/2022]
Abstract
Porcine reproductive and respiratory syndrome (PRRS), caused by PRRSV, has ranked among the most economically important veterinary infectious diseases globally. Recently, tripartite motif (TRIMs) family members have arisen as novel restriction factors in antiviral immunity. Noteworthy, TRIM26 was reported as a binding partner of IRF3, TBK1, TAB1, and NEMO, yet its role in virus infection remains controversial. Herein, we showed that TRIM26 bound N protein by the C-terminal PRY/SPRY domain. Moreover, ectopic expression of TRIM26 impaired PRRSV replication and induced degradation of N protein. The anti-PRRSV activity was independent of the nuclear localization signal (NLS). Instead, deletion of the RING domain, or the PRY/SPRY portion, abrogated the antiviral function. Finally, siRNA depletion of TRIM26 resulted in enhanced production of viral RNA and virus yield in porcine alveolar macrophages (PAMs) after PRRSV infection. Overexpression of an RNAi-resistant TRIM26 rescue-plasmid led to the acquisition of PRRSV restriction in TRIM26-knockdown cells. Together, these data add TRIM26 as a potential target for drug design against PRRSV.
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Affiliation(s)
- Pandeng Zhao
- College of Veterinary Medicine, Henan University of Animal Husbandry and Economy, Zhengzhou, 450046, China
| | - Huiyuan Jing
- College of Veterinary Medicine, Henan University of Animal Husbandry and Economy, Zhengzhou, 450046, China.
| | - Wang Dong
- College of Veterinary Medicine, Henan University of Animal Husbandry and Economy, Zhengzhou, 450046, China
| | - Erzhen Duan
- College of Biological Engineering, Henan University of Technology, Zhengzhou, 450001, China
| | - Wenting Ke
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China
| | - Ran Tao
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China
| | - Yang Li
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, China
| | - Sufang Cao
- College of Veterinary Medicine, Henan University of Animal Husbandry and Economy, Zhengzhou, 450046, China
| | - Haihua Wang
- College of Veterinary Medicine, Henan University of Animal Husbandry and Economy, Zhengzhou, 450046, China
| | - Yan Zhang
- College of Veterinary Medicine, Henan University of Animal Husbandry and Economy, Zhengzhou, 450046, China
| | - Yanting Sun
- College of Veterinary Medicine, Henan University of Animal Husbandry and Economy, Zhengzhou, 450046, China
| | - Jinhe Wang
- College of Veterinary Medicine, Henan University of Animal Husbandry and Economy, Zhengzhou, 450046, China
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Ujike M, Kawachi Y, Matsunaga Y, Etho Y, Asanuma H, Kamitani W, Taguchi F. Characterization of Localization and Export Signals of Bovine Torovirus Nucleocapsid Protein Responsible for Extensive Nuclear and Nucleolar Accumulation and Their Importance for Virus Growth. J Virol 2021; 95:e02111-20. [PMID: 33177195 PMCID: PMC7925113 DOI: 10.1128/jvi.02111-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 11/02/2020] [Indexed: 11/20/2022] Open
Abstract
Torovirus (ToV) has recently been classified into the new family Tobaniviridae, although historically, it belonged to the Coronavirus (CoV) family. The nucleocapsid (N) proteins of CoVs are predominantly localized in the cytoplasm, where the viruses replicate, but in some cases the proteins are partially located in the nucleolus. Many studies have investigated the subcellular localization and nucleocytoplasmic trafficking signals of the CoV N proteins, but little is known about ToV N proteins. Here, we studied the subcellular localization of the bovine ToV (BToV) N protein (BToN) and characterized its nucleocytoplasmic trafficking signals. Unlike other CoVs, BToN in infected cells was transported mainly to the nucleolus during early infection but was distributed predominantly in the nucleoplasm rather than in the nucleolus during late infection. Interestingly, a small quantity of BToN was detected in the cytoplasm during infection. Examination of a comprehensive set of substitution or deletion mutants of BToN fused with enhanced green fluorescent protein (EGFP) revealed that clusters of arginine (R) residues comprise nuclear/nucleolar localization signals (NLS/NoLS), and the C-terminal region served as a chromosomal maintenance 1 (CRM1)-independent nuclear export signal (NES). Moreover, recombinant viruses with mutations in the NLS/NoLS, but retaining nuclear accumulation, were successfully rescued and showed slightly reduced growth ability, while the virus that lost the NLS/NoLS-mediated nuclear accumulation of BToN was not rescued. These results indicate that BToN uniquely accumulates mainly in nuclear compartments during infection, regulated by an R-rich NLS/NoLS and a CRM1-independent NES, and that the BToN accumulation in the nuclear compartment driven by NLS/NoLS is important for virus growth.IMPORTANCE ToVs are diarrhea-causing pathogens detected in many species, including humans. BToV has spread worldwide, leading to economic loss, and there is currently no treatment or vaccine available. Positive-stranded RNA viruses, including ToVs, replicate in the cytoplasm, and their structural proteins generally accumulate in the cytoplasm. Interestingly, BToN accumulated predominantly in the nucleus/nucleolus during all infectious processes, with only a small fraction accumulating in the cytoplasm despite being a major structural protein. Furthermore, we identified unique nucleocytoplasmic trafficking signals and demonstrated the importance of NLS/NoLS for virus growth. This study is the first to undertake an in-depth investigation of the subcellular localization and intracellular trafficking signals of BToN. Our findings additionally suggest that the NLS/NoLS-mediated nuclear accumulation of BToN is important for virus replication. An understanding of the unique features of BToV may provide novel insights into the assembly mechanisms of not only ToVs but also other positive-stranded RNA viruses.
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Affiliation(s)
- Makoto Ujike
- Laboratory of Veterinary Infectious Diseases, Faculty of Veterinary Medicine, Nippon Veterinary and Life Science University, Tokyo, Japan
- Research Center for Animal Life Science, Nippon Veterinary and Life Science University, Tokyo, Japan
| | - Yukako Kawachi
- Laboratory of Veterinary Infectious Diseases, Faculty of Veterinary Medicine, Nippon Veterinary and Life Science University, Tokyo, Japan
| | - Yui Matsunaga
- Laboratory of Veterinary Infectious Diseases, Faculty of Veterinary Medicine, Nippon Veterinary and Life Science University, Tokyo, Japan
| | - Yuka Etho
- Laboratory of Veterinary Infectious Diseases, Faculty of Veterinary Medicine, Nippon Veterinary and Life Science University, Tokyo, Japan
| | - Hideki Asanuma
- Influenza Virus Research Center, National Institute of Infectious Diseases, Tokyo, Japan
| | - Wataru Kamitani
- Department of Infectious Diseases and Host Defense, Gunma University Graduate School of Medicine, Gunma, Japan
| | - Fumihiro Taguchi
- Laboratory of Veterinary Infectious Diseases, Faculty of Veterinary Medicine, Nippon Veterinary and Life Science University, Tokyo, Japan
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Hatmal MM, Alshaer W, Al-Hatamleh MAI, Hatmal M, Smadi O, Taha MO, Oweida AJ, Boer JC, Mohamud R, Plebanski M. Comprehensive Structural and Molecular Comparison of Spike Proteins of SARS-CoV-2, SARS-CoV and MERS-CoV, and Their Interactions with ACE2. Cells 2020; 9:E2638. [PMID: 33302501 PMCID: PMC7763676 DOI: 10.3390/cells9122638] [Citation(s) in RCA: 125] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 12/01/2020] [Accepted: 12/04/2020] [Indexed: 01/03/2023] Open
Abstract
The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has recently emerged in China and caused a disease called coronavirus disease 2019 (COVID-19). The virus quickly spread around the world, causing a sustained global outbreak. Although SARS-CoV-2, and other coronaviruses, SARS-CoV and Middle East respiratory syndrome CoV (MERS-CoV) are highly similar genetically and at the protein production level, there are significant differences between them. Research has shown that the structural spike (S) protein plays an important role in the evolution and transmission of SARS-CoV-2. So far, studies have shown that various genes encoding primarily for elements of S protein undergo frequent mutation. We have performed an in-depth review of the literature covering the structural and mutational aspects of S protein in the context of SARS-CoV-2, and compared them with those of SARS-CoV and MERS-CoV. Our analytical approach consisted in an initial genome and transcriptome analysis, followed by primary, secondary and tertiary protein structure analysis. Additionally, we investigated the potential effects of these differences on the S protein binding and interactions to angiotensin-converting enzyme 2 (ACE2), and we established, after extensive analysis of previous research articles, that SARS-CoV-2 and SARS-CoV use different ends/regions in S protein receptor-binding motif (RBM) and different types of interactions for their chief binding with ACE2. These differences may have significant implications on pathogenesis, entry and ability to infect intermediate hosts for these coronaviruses. This review comprehensively addresses in detail the variations in S protein, its receptor-binding characteristics and detailed structural interactions, the process of cleavage involved in priming, as well as other differences between coronaviruses.
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Affiliation(s)
- Ma’mon M. Hatmal
- Department of Medical Laboratory Sciences, Faculty of Applied Health Sciences, The Hashemite University, Zarqa 13133, Jordan
| | - Walhan Alshaer
- Cell Therapy Center (CTC), The University of Jordan, Amman 11942, Jordan
| | - Mohammad A. I. Al-Hatamleh
- Department of Immunology, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian, Kelantan 16150, Malaysia; (M.A.I.A.-H.); (R.M.)
| | | | - Othman Smadi
- Department of Biomedical Engineering, Faculty of Engineering, The Hashemite University, Zarqa 13133, Jordan;
| | - Mutasem O. Taha
- Drug Design and Discovery Unit, Department of Pharmaceutical Sciences, Faculty of Pharmacy, The University of Jordan, Amman 11942, Jordan;
| | - Ayman J. Oweida
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC J1H 5N4, Canada;
| | - Jennifer C. Boer
- Translational Immunology and Nanotechnology Unit, School of Health and Biomedical Sciences, RMIT University, Bundoora 3083, Australia; (J.C.B.); (M.P.)
| | - Rohimah Mohamud
- Department of Immunology, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian, Kelantan 16150, Malaysia; (M.A.I.A.-H.); (R.M.)
- Hospital Universiti Sains Malaysia, Health Campus, Kubang Kerian, Kelantan 16150, Malaysia
| | - Magdalena Plebanski
- Translational Immunology and Nanotechnology Unit, School of Health and Biomedical Sciences, RMIT University, Bundoora 3083, Australia; (J.C.B.); (M.P.)
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Identification and Characterization of the Nucleolar Localization Signal of Autographa californica Multiple Nucleopolyhedrovirus LEF5. J Virol 2020; 94:JVI.01891-19. [PMID: 31776271 DOI: 10.1128/jvi.01891-19] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 11/19/2019] [Indexed: 11/20/2022] Open
Abstract
Autographa californica multiple nucleopolyhedrovirus (AcMNPV) late expression factor 5 (LEF5) is highly conserved in all sequenced baculovirus genomes and plays an important role in production of infectious viral progeny. In this study, nucleolar localization of AcMNPV LEF5 was characterized. Through transcriptome analysis, we identified two putative nucleolar proteins, Spodoptera frugiperda nucleostemin (SfNS) and fibrillarin (SfFBL), from Sf9 cells. Immunofluorescence analysis demonstrated that SfNS and SfFBL were localized to the nucleolus. AcMNPV infection resulted in reorganization of the nucleoli of infected cells. Colocalization of LEF5 and SfNS showed that AcMNPV LEF5 was localized to the nucleolus in Sf9 cells. Bioinformatic analysis revealed that basic amino acids of LEF5 are enriched at residues 184 to 213 and may contain a nucleolar localization signal (NoLS). Green fluorescent protein (GFP) fused to NoLS of AcMNPV LEF5 localized to the nucleoli of transfected cells. Multiple-point mutation analysis demonstrated that amino acid residues 197 to 204 are important for nucleolar localization of LEF5. To identify whether the NoLS in AcMNPV LEF5 is important for production of viral progeny, a lef5-null AcMNPV bacmid was constructed; several NoLS-mutated LEF5 proteins were reinserted into the lef5-null AcMNPV bacmid with a GFP reporter. The constructs containing point mutations at residues 185 to 189 or 197 to 204 in AcMNPV LEF5 resulted in reduction in production of infectious viral progeny and occlusion body yield in bacmid-transfected cells. Together, these data suggested that AcMNPV LEF5 contains an NoLS, which is important for nucleolar localization of LEF5, progeny production, and occlusion body production.IMPORTANCE Many viruses, including human and plant viruses, target nucleolar functions as part of their infection strategy. However, nucleolar localization for baculovirus proteins has not yet been characterized. In this study, two nucleolar proteins, SfNS and SfFBL, were identified in Sf9 cells. Our results showed that Autographa californica multiple nucleopolyhedrovirus (AcMNPV) infection resulted in redistribution of the nucleoli of infected cells. We demonstrated that AcMNPV late expression factor 5 (LEF5) could localize to the nucleolus and contains a nucleolar localization signal (NoLS), which is important for nucleolar localization of AcMNPV LEF5 and for production of viral progeny and yield of occlusion bodies.
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Acar DD, Stroobants VJE, Favoreel H, Saelens X, Nauwynck HJ. Identification of peptide domains involved in the subcellular localization of the feline coronavirus 3b protein. J Gen Virol 2019; 100:1417-1430. [PMID: 31483243 PMCID: PMC7079696 DOI: 10.1099/jgv.0.001321] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Feline coronavirus (FCoV) has been identified as the aetiological agent of feline infectious peritonitis (FIP), a highly fatal systemic disease in cats. FCoV open reading frame 3 (ORF3) encodes accessory proteins 3a, 3b and 3 c. The FCoV 3b accessory protein consists of 72 amino acid residues and localizes to nucleoli and mitochondria. The present work focused on peptide domains within FCoV 3b that drive its intracellular trafficking. Transfection of different cell types with FCoV 3b fused to enhanced green fluorescent protein (EGFP) or 3×FLAG confirmed localization of FCoV 3b in the mitochondria and nucleoli. Using serial truncated mutants, we showed that nucleolar accumulation is controlled by a joint nucleolar and nuclear localization signal (NoLS/NLS) in which the identified overlapping pat4 motifs (residues 53–57) play a critical role. Mutational analysis also revealed that mitochondrial translocation is mediated by N-terminal residues 10–35, in which a Tom20 recognition motif (residues 13–17) and two other overlapping hexamers (residues 24–30) associated with mitochondrial targeting were identified. In addition, a second Tom20 recognition motif was identified further downstream (residues 61–65), although the mitochondrial translocation evoked by these residues seemed less efficient as a diffuse cytoplasmic distribution was also observed. Assessing the spatiotemporal distribution of FCoV 3b did not provide convincing evidence of dynamic shuttling behaviour between the nucleoli and the mitochondria.
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Affiliation(s)
- Delphine D. Acar
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Veerle J. E. Stroobants
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Herman Favoreel
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Xavier Saelens
- VIB-UGent Center for Medical Biotechnology, VIB, Ghent, Belgium; Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium
| | - Hans J. Nauwynck
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
- *Correspondence: Hans J. Nauwynck,
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Nuclear localization signal in TRIM22 is essential for inhibition of type 2 porcine reproductive and respiratory syndrome virus replication in MARC-145 cells. Virus Genes 2019; 55:660-672. [PMID: 31375995 PMCID: PMC7089487 DOI: 10.1007/s11262-019-01691-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 07/23/2019] [Indexed: 12/11/2022]
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) infection causes one of the most economically important swine diseases worldwide. Tripartite motif-containing 22 (TRIM22), a TRIM family protein, has been identified as a crucial restriction factor that inhibits a group of human viruses. Currently, the role of cellular TRIM22 in PRRSV infection remains unclear. In the present study, we analyzed the effect of TRIM22 on PRRSV replication in vitro and explored the underlying mechanism. Ectopic expression of TRIM22 impaired the viral replication, while TRIM22-RNAi favored the replication of PRRSV in MARC-145 cells. Additionally, we observed that TRIM22 deletion SPRY domain or Nuclear localization signal (NLS) losses the ability to inhibit PRRSV replication. Finally, Co-IP analysis identified that TRIM22 interacts with PRRSV nucleocapsid (N) protein through the SPRY domain, while the NLS2 motif of N protein is involved in interaction with TRIM22. Although the concentration of PRRSV N protein was not altered in the presence of TRIM22, the abundance of N proteins from simian hemorrhagic fever virus (SHFV), equine arteritis virus (EAV), and murine lactate dehydrogenase-elevating virus (LDV) diminished considerably with increasing TRIM22 expression. Together, our findings uncover a previously unrecognized role for TRIM22 and extend the antiviral effects of TRIM22 to arteriviruses.
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Ke H, Lee S, Kim J, Liu HC, Yoo D. Interaction of PIAS1 with PRRS virus nucleocapsid protein mediates NF-κB activation and triggers proinflammatory mediators during viral infection. Sci Rep 2019; 9:11042. [PMID: 31363150 PMCID: PMC6667501 DOI: 10.1038/s41598-019-47495-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 07/08/2019] [Indexed: 12/21/2022] Open
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) activates NF-κB during infection. We examined the ability of all 22 PRRSV genes for NF-κB regulation and determined the nucleocapsid (N) protein as the NF-κB activator. Protein inhibitor of activated STAT1 (signal transducer and activator of transcription 1) (PIAS1) was identified as a cellular protein binding to N. PIAS1 is known to bind to p65 (RelA) in the nucleus and blocks its DNA binding, thus functions as a repressor of NF-κB. Binding of N to PIAS1 released p65 for NF-κB activation. The N-terminal half of PIAS1 was mapped as the N-binding domain, and this region overlapped its p65-binding domain. For N, the region between 37 and 72 aa was identified as the binding domain to PIAS1, and this domain alone was able to activate NF-κB. A nuclear localization signal (NLS) knock-out mutant N did not activate NF-κB, and this is mostly likely due to the lack of its interaction with PIAS1 in the nucleus, demonstrating the positive correlation between the binding of N to PIAS1 and the NF-κB activation. Our study reveals a role of N in the nucleus for NF-κB activation and proinflammatory cytokine production during infection.
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Affiliation(s)
- Hanzhong Ke
- Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Sera Lee
- Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Jineui Kim
- Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Hsiao-Ching Liu
- Department of Animal Science, North Carolina State University, Raleigh, NC, USA
| | - Dongwan Yoo
- Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
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Wang C, Zeng N, Liu S, Miao Q, Zhou L, Ge X, Han J, Guo X, Yang H. Interaction of porcine reproductive and respiratory syndrome virus proteins with SUMO-conjugating enzyme reveals the SUMOylation of nucleocapsid protein. PLoS One 2017; 12:e0189191. [PMID: 29236778 PMCID: PMC5728522 DOI: 10.1371/journal.pone.0189191] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 11/21/2017] [Indexed: 12/30/2022] Open
Abstract
SUMOylation is a reversible post-translational modification that regulates the function of target protein. In this study, we first predicted by software that the multiple proteins of porcine reproductive and respiratory syndrome virus (PRRSV) could be sumoylated. Next, we confirmed that Nsp1β, Nsp4, Nsp9, Nsp10 and nucleocapsid (N) protein of PRRSV could interact with the sole SUMO E2 conjugating enzyme Ubc9, and Ubc9 could be co-localized with Nsp1β, Nsp4, Nsp9 and Nsp10 in the cytoplasm, while with N protein in both the cytoplasm and nucleus. Finally, we demonstrated that N protein could be sumoylated by either SUMO1 or SUMO2/3. In addition, the overexpression of Ubc9 could inhibit viral genomic replication at early period of PRRSV infection and the knockdown of Ubc9 by siRNA could promote the virus replication. These findings reveal the SUMOylation property of PRRSV N protein and the involvement of Ubc9 in PRRSV replication through interaction with multiple proteins of PRRSV. To our knowledge, this is the first study indicating the interplay between SUMO modification system and PRRSV.
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Affiliation(s)
- Cong Wang
- Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine and State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing, People’s Republic of China
| | - Nanfang Zeng
- Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine and State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing, People’s Republic of China
| | - Siyu Liu
- Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine and State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing, People’s Republic of China
| | - Qi Miao
- Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine and State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing, People’s Republic of China
| | - Lei Zhou
- Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine and State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing, People’s Republic of China
| | - Xinna Ge
- Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine and State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing, People’s Republic of China
| | - Jun Han
- Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine and State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing, People’s Republic of China
| | - Xin Guo
- Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine and State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing, People’s Republic of China
- * E-mail: (XG); (HY)
| | - Hanchun Yang
- Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine and State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing, People’s Republic of China
- * E-mail: (XG); (HY)
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12
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Jing H, Zhou Y, Fang L, Ding Z, Wang D, Ke W, Chen H, Xiao S. DExD/H-Box Helicase 36 Signaling via Myeloid Differentiation Primary Response Gene 88 Contributes to NF-κB Activation to Type 2 Porcine Reproductive and Respiratory Syndrome Virus Infection. Front Immunol 2017; 8:1365. [PMID: 29123520 PMCID: PMC5662876 DOI: 10.3389/fimmu.2017.01365] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2017] [Accepted: 10/05/2017] [Indexed: 02/02/2023] Open
Abstract
DExD/H-box helicase 36 (DHX36) is known to be an ATP-dependent RNA helicase that unwinds the guanine-quadruplexes DNA or RNA, but emerging data suggest that it also functions as pattern recognition receptor in innate immunity. Porcine reproductive and respiratory syndrome virus (PRRSV) is an Arterivirus that has been devastating the swine industry worldwide. Interstitial pneumonia is considered to be one of the most obvious clinical signs of PRRSV infection, suggesting that the inflammatory response plays an important role in PRRSV pathogenesis. However, whether DHX36 is involved in PRRSV-induced inflammatory cytokine expression remains unclear. In this study, we found that PRRSV infection increased the expression of DHX36. Knockdown of DHX36 and its adaptor myeloid differentiation primary response gene 88 (MyD88) by small-interfering RNA in MARC-145 cells significantly reduced NF-κB activation and pro-inflammatory cytokine expression after PRRSV infection. Further investigation revealed that PRRSV nucleocapsid protein interacted with the N-terminal quadruplex binding domain of DHX36, which in turn augmented nucleocapsid protein-induced NF-κB activation. Taken together, our results suggest that DHX36-MyD88 has a relevant role in the recognition of PRRSV nucleocapsid protein and in the subsequent activation of pro-inflammatory NF-κB pathway.
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Affiliation(s)
- Huiyuan Jing
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China
| | - Yanrong Zhou
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China
| | - Liurong Fang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China
| | - Zhen Ding
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China
| | - Dang Wang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China
| | - Wenting Ke
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China
| | - Huanchun Chen
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China
| | - Shaobo Xiao
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan, China
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13
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The viral innate immune antagonism and an alternative vaccine design for PRRS virus. Vet Microbiol 2017; 209:75-89. [PMID: 28341332 PMCID: PMC7111430 DOI: 10.1016/j.vetmic.2017.03.014] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 03/10/2017] [Accepted: 03/13/2017] [Indexed: 02/06/2023]
Abstract
PRRS virus has evolved to suppress the antiviral innate immunity during infection. Type I interferons are potent antiviral cytokines and function to stimulate the adaptive immune responses. Six viral proteins have been identified as interferon antagonists and characterized for their molecular actions. Interferon antagonism-negative viruses are attenuated and have been proven induce protective immunity. Interferon suppression-negative PRRS virus may serve as an alternative vaccine for PRRS.
Porcine reproductive and respiratory syndrome (PRRS) remains one of the most economically significant diseases in the swine industry worldwide. The current vaccines are less satisfactory to confer protections from heterologous infections and long-term persistence, and the need for better vaccines are urgent. The immunological hallmarks in PRRSV-infected pigs include the unusually poor production of type I interferons (IFNs-α/β) and the aberrant and delayed adaptive immune responses, indicating that PRRSV has the ability to suppress both innate and adaptive immune responses in the host. Type I IFNs are the potent antiviral cytokines and recent studies reveal their pleiotropic functions in the priming of expansion and maturation of adaptive immunity. Thus, IFN antagonism-negative PRRSV is hypothesized to be attenuated and to build effective and broad- spectrum innate and adaptive immune responses in pigs. Such vaccines are promising alternatives to traditional vaccines for PRRSV.
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14
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Lee YJ, Lee C. Ivermectin inhibits porcine reproductive and respiratory syndrome virus in cultured porcine alveolar macrophages. Arch Virol 2015; 161:257-68. [PMID: 26518309 DOI: 10.1007/s00705-015-2653-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 10/18/2015] [Indexed: 11/28/2022]
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) is a devastating viral pathogen of swine that causes huge financial losses in the pig industry worldwide. Ivermectin is known to be a potent inhibitor of importin α/β-mediated nuclear transport and exhibits antiviral activity towards several RNA viruses by blocking the nuclear trafficking of viral proteins. Although PRRSV replication occurs exclusively in the cytoplasm of infected cells, the nucleocapsid (N) protein has been shown to distinctly localize in the nucleus and nucleolus throughout infection. Here, we sought to assess whether ivermectin suppresses PRRSV replication in cultured porcine alveolar macrophage (PAM) cells and to investigate the effect of ivermectin on the subcellular localization of the PRRSV N protein. Our data demonstrate that ivermectin treatment inhibits PRRSV infection in PAM-pCD163 cells in a dose-dependent manner. The antiviral activity of ivermectin on PRRSV replication was most effective when cells were treated during the early stage of infection. Treatment of PRRSV-infected cells with ivermectin significantly suppressed viral RNA synthesis, viral protein expression, and progeny virus production. However, immunofluorescence and cell fractionation assays revealed that ivermectin was incapable of disrupting the nuclear localization of the N protein, both in PRRSV-infected PAM-pCD163 cells and in PAM cells stably expressing the PRRSV N protein. This finding suggests that an alternative mechanism of action accounts for the ability of ivermectin to diminish PRRSV replication. Taken together, our results suggest that ivermectin is an invaluable therapeutic or preventative agent against PRRSV infection.
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Affiliation(s)
- Yoo Jin Lee
- Animal Virology Laboratory, School of Life Sciences, College of Natural Sciences, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, 702-701, Republic of Korea
| | - Changhee Lee
- Animal Virology Laboratory, School of Life Sciences, College of Natural Sciences, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, 702-701, Republic of Korea.
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15
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Fan B, Liu X, Bai J, Li Y, Zhang Q, Jiang P. The 15N and 46R Residues of Highly Pathogenic Porcine Reproductive and Respiratory Syndrome Virus Nucleocapsid Protein Enhance Regulatory T Lymphocytes Proliferation. PLoS One 2015; 10:e0138772. [PMID: 26397116 PMCID: PMC4580451 DOI: 10.1371/journal.pone.0138772] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 08/09/2015] [Indexed: 12/14/2022] Open
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) negatively modulates host immune responses, resulting in persistent infection and immunosuppression. PRRSV infection increases the number of PRRSV-specific regulatory T lymphocytes (Tregs) in infected pigs. However, the target antigens for Tregs proliferation in PRRSV infection have not been fully understood. In this study, we demonstrated that the highly pathogenic PRRSV (HP-PRRSV) induced more CD4+CD25+Foxp3+ Tregs than classical PRRSV (C-PRRSV) strain. Of the recombinant GP5, M and N proteins of HP-PRRSV expressed in baculovirus expression systems, only N protein induced Tregs proliferation. The Tregs assays showed that three amino-acid regions, 15–21, 42–48 and 88–94, in N protein played an important role in induction of Tregs proliferation with synthetic peptides covering the whole length of N protein. By using reverse genetic methods, it was firstly found that the 15N and 46R residues in PRRSV N protein were critical for induction of Tregs proliferation. The phenotype of induced Tregs closely resembled that of transforming-growth-factor-β-secreting T helper 3 Tregs in swine. These data should be useful for understanding the mechanism of immunity to PRRSV and development of infection control strategies in the future.
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Affiliation(s)
- Baochao Fan
- Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Xing Liu
- Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Juan Bai
- Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Yufeng Li
- Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Qiaoya Zhang
- Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
| | - Ping Jiang
- Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
- * E-mail:
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16
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Rawlinson SM, Moseley GW. The nucleolar interface of
RNA
viruses. Cell Microbiol 2015; 17:1108-20. [DOI: 10.1111/cmi.12465] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Revised: 05/27/2015] [Accepted: 06/01/2015] [Indexed: 02/06/2023]
Affiliation(s)
- Stephen M. Rawlinson
- Viral Pathogenesis Laboratory Department of Biochemistry and Molecular Biology Bio21 Molecular Science and Biotechnology Institute The University of Melbourne Melbourne Australia
| | - Gregory W. Moseley
- Viral Pathogenesis Laboratory Department of Biochemistry and Molecular Biology Bio21 Molecular Science and Biotechnology Institute The University of Melbourne Melbourne Australia
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17
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Liu X, Fan B, Bai J, Wang H, Li Y, Jiang P. The N-N non-covalent domain of the nucleocapsid protein of type 2 porcine reproductive and respiratory syndrome virus enhances induction of IL-10 expression. J Gen Virol 2015; 96:1276-1286. [PMID: 25614594 DOI: 10.1099/vir.0.000061] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 01/15/2015] [Indexed: 12/24/2022] Open
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) usually establishes a prolonged infection and causes an immunosuppressive state. It has been proposed that IL-10 plays an important role in PRRSV-induced immunosuppression. However, this mechanism has not been completely elucidated. In this study, we found that transfection of 3D4/2 macrophages with the N protein gene of type 2 PRRSV significantly upregulated IL-10 expression at the transcriptional level. Moreover, alanine substitution mutation analysis revealed that the N protein residues 33-37, 65-68 and 112-123 were related to the upregulation of IL-10 promoter activity. Recombinant PRRSV with mutations at residues 33-37 in the N protein (rQ33-5A and rS36A) recovered from corresponding infectious cDNA clones and induced significantly lower levels of IL-10 production in infected monocyte-derived dendritic cells, as compared with their revertants rQ33-5A(R) and rS36A(R), and the wild-type recombinant PRRSV strain rNT/wt. These data indicate that the type 2 PRRSV N protein plays an important role in IL-10 induction and the N-N non-covalent domain is associated with this activity.
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Affiliation(s)
- Xing Liu
- Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, PR China
| | - Baochao Fan
- Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, PR China
| | - Juan Bai
- Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, PR China
| | - Haiyan Wang
- Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, PR China
| | - Yufeng Li
- Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, PR China
| | - Ping Jiang
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, PR China.,Key Laboratory of Animal Diseases Diagnostic and Immunology, Ministry of Agriculture, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, PR China
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18
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Han M, Yoo D. Engineering the PRRS virus genome: updates and perspectives. Vet Microbiol 2014; 174:279-295. [PMID: 25458419 PMCID: PMC7172560 DOI: 10.1016/j.vetmic.2014.10.007] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Revised: 10/13/2014] [Accepted: 10/15/2014] [Indexed: 12/03/2022]
Abstract
We review PRRSV infectious clones and their applications. 14 infectious clones are available so far for genotypes I and II. Genomic mutations, insertions, deletions, and replacements are successful. We discuss advances and utilization of PRRSV reverse genetics and future potential.
Porcine reproductive and respiratory syndrome virus (PRRSV) is endemic in most pig producing countries worldwide and causes enormous economic losses to the pork industry. Infectious clones for PRRSV have been constructed, and so far at least 14 different infectious clones are available representing both genotypes I and II. Two strategies have been taken for progeny reconstitution: RNA transfection and DNA transfection. Mutations, insertions, deletions, and replacements of the viral genome have been employed to study the structure function relationship, foreign gene expression, functional complementation, and virulence determinants. Essential regions and non-essential regions for viral replication have been identified in both the coding regions and non-encoding regions. Foreign sequences have successfully been inserted into the nsp2 and N regions and in the space between ORF1b and ORF2a. Chimeras between member viruses in the family Arteriviridae have also been constructed and utilized to study cell tropism and functional complementation. This review discusses the advances and utilization of PRRSV reverse genetics and its potential for future research.
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Affiliation(s)
- Mingyuan Han
- Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL 61802, United States
| | - Dongwan Yoo
- Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL 61802, United States.
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19
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Salvetti A, Greco A. Viruses and the nucleolus: the fatal attraction. Biochim Biophys Acta Mol Basis Dis 2013; 1842:840-7. [PMID: 24378568 PMCID: PMC7135015 DOI: 10.1016/j.bbadis.2013.12.010] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 12/05/2013] [Accepted: 12/09/2013] [Indexed: 12/13/2022]
Abstract
Viruses are small obligatory parasites and as a consequence, they have developed sophisticated strategies to exploit the host cell's functions to create an environment that favors their own replication. A common feature of most – if not all – families of human and non-human viruses concerns their interaction with the nucleolus. The nucleolus is a multifunctional nuclear domain, which, in addition to its well-known role in ribosome biogenesis, plays several crucial other functions. Viral infection induces important nucleolar alterations. Indeed, during viral infection numerous viral components localize in nucleoli, while various host nucleolar proteins are redistributed in other cell compartments or are modified, and non-nucleolar cellular proteins reach the nucleolus. This review highlights the interactions reported between the nucleolus and some human or animal viral families able to establish a latent or productive infection, selected on the basis of their known interactions with the nucleolus and the nucleolar activities, and their links with virus replication and/or pathogenesis. This article is part of a Special Issue entitled: Role of the Nucleolus in Human Disease. Most viruses interact with the nucleolus that plays a major role in virus life cycle. Virus/nucleolus interaction is crucial for virus replication and pathogenesis. Role of nucleoli in the infection with selected RNA viruses and herpes viruses
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Affiliation(s)
- Anna Salvetti
- Centre International de Recherche en Infectiologie (CIRI, International Center for Infectiology Research), Inserm U1111, CNRS UMR5308, Ecole Normale Supérieure de Lyon, Université de Lyon, 46 Allée d'Italie, 69365 Lyon CEDEX, France; LabEx Ecofect, Université de Lyon, 69007 Lyon, France.
| | - Anna Greco
- Centre International de Recherche en Infectiologie (CIRI, International Center for Infectiology Research), Inserm U1111, CNRS UMR5308, Ecole Normale Supérieure de Lyon, Université de Lyon, 46 Allée d'Italie, 69365 Lyon CEDEX, France; LabEx Ecofect, Université de Lyon, 69007 Lyon, France.
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20
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Abstract
Arteriviruses are positive-stranded RNA viruses that infect mammals. They can cause persistent or asymptomatic infections, but also acute disease associated with a respiratory syndrome, abortion or lethal haemorrhagic fever. During the past two decades, porcine reproductive and respiratory syndrome virus (PRRSV) and, to a lesser extent, equine arteritis virus (EAV) have attracted attention as veterinary pathogens with significant economic impact. Particularly noteworthy were the 'porcine high fever disease' outbreaks in South-East Asia and the emergence of new virulent PRRSV strains in the USA. Recently, the family was expanded with several previously unknown arteriviruses isolated from different African monkey species. At the molecular level, arteriviruses share an intriguing but distant evolutionary relationship with coronaviruses and other members of the order Nidovirales. Nevertheless, several of their characteristics are unique, including virion composition and structure, and the conservation of only a subset of the replicase domains encountered in nidoviruses with larger genomes. During the past 15 years, the advent of reverse genetics systems for EAV and PRRSV has changed and accelerated the structure-function analysis of arterivirus RNA and protein sequences. These systems now also facilitate studies into host immune responses and arterivirus immune evasion and pathogenesis. In this review, we have summarized recent advances in the areas of arterivirus genome expression, RNA and protein functions, virion architecture, virus-host interactions, immunity, and pathogenesis. We have also briefly reviewed the impact of these advances on disease management, the engineering of novel candidate live vaccines and the diagnosis of arterivirus infection.
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Affiliation(s)
- Eric J Snijder
- Molecular Virology Department, Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Marjolein Kikkert
- Molecular Virology Department, Department of Medical Microbiology, Leiden University Medical Center, Leiden, The Netherlands
| | - Ying Fang
- Department of Diagnostic Medicine and Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, USA.,Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, South Dakota, USA
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21
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Wang ZW, Sun N, Wu CH, Jiang JB, Bai YS, Li HQ. In vitro antiviral activity and underlying molecular mechanisms of dipotassium glycyrrhetate against porcine reproductive and respiratory syndrome virus. Antivir Ther 2013; 18:997-1004. [PMID: 23872789 DOI: 10.3851/imp2662] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/11/2013] [Indexed: 10/26/2022]
Abstract
BACKGROUND Porcine reproductive and respiratory syndrome virus (PRRSV) has caused large economic losses in the swine industry. Currently, there is no effective way to prevent PRRSV infection. In this study, we investigated the inhibitory effect of dipotassium glycyrrhetate (DG), a derivative of glycyrrhetinic acid, on PRRSV infection ability. METHODS The cytotoxicity of DG was measured by MTT assay, and the effects of DG on PRRSV N gene/protein were investigated using real-time PCR, western blot and immunofluorescence assay. In addition, the effect of DG on cell apoptosis was analysed by fluorescence staining. RESULTS Our results indicated that DG could effectively inhibit virus replication and N gene expression in MARC-145 cells infected with PRRSV. When the infected cells received DG, the numbers of apoptotic cells were decreased, and the cleaved caspase-3 contents were decreased dramatically. CONCLUSIONS Our study demonstrates that DG could effectively inhibit the PRRS virus via multiple pathways including inhibition of virus replication and N gene expression and reduction of apoptotic cells. DG can serve as a potential chemical for PRRSV prevention and control.
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Affiliation(s)
- Zhi-Wei Wang
- College of Animal Science and Veterinary Medicine, Shanxi Agricultural University, Taigu, PR China
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22
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Jourdan SS, Osorio F, Hiscox JA. An interactome map of the nucleocapsid protein from a highly pathogenic North American porcine reproductive and respiratory syndrome virus strain generated using SILAC-based quantitative proteomics. Proteomics 2012; 12:1015-23. [PMID: 22522808 PMCID: PMC7167637 DOI: 10.1002/pmic.201100469] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Positive strand RNA viruses replicate in the cytoplasm of an infected cell and encode nucleocapsid proteins. These proteins function to promote encapsidation of the RNA genome and virus particle assembly as well as playing potential roles in viral RNA synthesis. Nucleocapsid proteins can also associate with cellular proteins and signaling cascades. The arterivirus nucleocapsid (N) protein is no exception and localizes to both the cytoplasm and the nucleolus in virus‐infected cells. This study generated an interactome map of the N protein from a highly virulent North American strain of porcine reproductive and respiratory syndrome virus (PRRSV). This is a major pathogen of swine resulting in significant morbidity and mortality. Crucial to the study was the use of SILAC coupled to affinity purification using GFP‐traps and LC‐MS/MS. This approach has not been applied before to the investigation of host/viral protein interactomes and this study revealed that the PRRSV N protein interacts with the host cell protein synthesis machinery especially at the level of translation initiation as well as with the RNA post‐transcriptional modification machinery. Applications of the dataset can include studies of virus/host interactions and the design of live attenuated recombinant vaccines.
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Affiliation(s)
- Stefanie S Jourdan
- Institute of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK
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23
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Poly(A)-binding protein interacts with the nucleocapsid protein of porcine reproductive and respiratory syndrome virus and participates in viral replication. Antiviral Res 2012; 96:315-23. [PMID: 22985629 DOI: 10.1016/j.antiviral.2012.09.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Revised: 08/09/2012] [Accepted: 09/06/2012] [Indexed: 11/20/2022]
Abstract
Interactions between host factors and the viral protein play important roles in host adaptation and regulation of virus replication. Poly(A)-binding protein (PABP), a host cellular protein that enhances translational efficiency by circularizing mRNAs, was identified by yeast two-hybrid screening as a cellular partner for PRRSV nucleocapsid (N) protein in porcine alveolar macrophages. The specific interaction of PRRSV N protein with PABP was confirmed in infected cells by co-immunoprecipitation and in vitro by GST pull-down assay. We showed by confocal microscopy that the PABP co-localized with the PRRSV N protein. Using a series of deletion mutants, the interactive domain of N protein with PABP was mapped to a region of amino acids 52-69. For PABP, C-terminal half, which interestingly interacts other translation regulators, was determined to be the domain interactive with N protein. Short hairpin RNA (shRNA)-mediated silencing of PABP in cells resulted in significantly reduced PRRSV RNA synthesis, viral encoded protein expression and viral titer. Overall, the results presented here point toward an important role for PABP in regulating PRRSV replication.
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24
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Du Y, Pattnaik AK, Song C, Yoo D, Li G. Glycosyl-phosphatidylinositol (GPI)-anchored membrane association of the porcine reproductive and respiratory syndrome virus GP4 glycoprotein and its co-localization with CD163 in lipid rafts. Virology 2012; 424:18-32. [PMID: 22222209 PMCID: PMC7111931 DOI: 10.1016/j.virol.2011.12.009] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Revised: 10/22/2011] [Accepted: 12/11/2011] [Indexed: 11/25/2022]
Abstract
The porcine reproductive and respiratory syndrome virus (PRRSV) glycoprotein 4 (GP4) resembles a typical type I membrane protein in its structure but lacks a hydrophilic tail at the C-terminus, suggesting that GP4 may be a lipid-anchored membrane protein. Using the human decay-accelerating factor (DAF; CD55), a known glycosyl-phosphatidylinositol (GPI) lipid-anchored protein, chimeric constructs were made to substitute the GPI-anchor domain of DAF with the putative lipid-anchor domain of GP4, and their membrane association and lipase cleavage were determined in cells. The DAF-GP4 fusion protein was transported to the plasma membrane and was cleaved by phosphatidylinositol-specific phospholipase C (PI-PLC), indicating that the C-terminal domain of GP4 functions as a GPI anchor. Mutational studies for residues adjacent to the GPI modification site and characterization of respective mutant viruses generated from infectious cDNA clones show that the ability of GP4 for membrane association corresponded to virus viability and growth characteristics. The residues T158 (ω − 2, where ω is the GPI moiety at E160), P159 (ω − 1), and M162 (ω + 2) of GP4 were determined to be important for virus replication, with M162 being of particular importance for virus infectivity. The complete removal of the peptide–anchor domain in GP4 resulted in a complete loss of virus infectivity. The depletion of cholesterol from the plasma membrane of cells reduced the virus production, suggesting a role of lipid rafts in PRRSV infection. Remarkably, GP4 was found to co-localize with CD163 in the lipid rafts on the plasma membrane. Since CD163 has been reported as a cellular receptor for PRRSV and GP4 has been shown to interact with this receptor, our data implicates an important role of lipid rafts during entry of the virus.
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Affiliation(s)
- Yijun Du
- Department of Pathobiology, University of Illinois at Urbana-Champaign, Urbana, IL 61802, USA
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Affiliation(s)
- Mark O. J. Olson
- Dept. Biochemistry, University of Mississippi Medical Center, North State St. 2500, Jackson, 39216 Mississippi USA
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Scott MS, Troshin PV, Barton GJ. NoD: a Nucleolar localization sequence detector for eukaryotic and viral proteins. BMC Bioinformatics 2011; 12:317. [PMID: 21812952 PMCID: PMC3166288 DOI: 10.1186/1471-2105-12-317] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Accepted: 08/03/2011] [Indexed: 12/15/2022] Open
Abstract
Background Nucleolar localization sequences (NoLSs) are short targeting sequences responsible for the localization of proteins to the nucleolus. Given the large number of proteins experimentally detected in the nucleolus and the central role of this subnuclear compartment in the cell, NoLSs are likely to be important regulatory elements controlling cellular traffic. Although many proteins have been reported to contain NoLSs, the systematic characterization of this group of targeting motifs has only recently been carried out. Results Here, we describe NoD, a web server and a command line program that predicts the presence of NoLSs in proteins. Using the web server, users can submit protein sequences through the NoD input form and are provided with a graphical output of the NoLS score as a function of protein position. While the web server is most convenient for making prediction for just a few proteins, the command line version of NoD can return predictions for complete proteomes. NoD is based on our recently described human-trained artificial neural network predictor. Through stringent independent testing of the predictor using available experimentally validated NoLS-containing eukaryotic and viral proteins, the NoD sensitivity and positive predictive value were estimated to be 71% and 79% respectively. Conclusions NoD is the first tool to provide predictions of nucleolar localization sequences in diverse eukaryotes and viruses. NoD can be run interactively online at http://www.compbio.dundee.ac.uk/nod or downloaded to use locally.
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Affiliation(s)
- Michelle S Scott
- Division of Biological Chemistry and Drug Discovery, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK.
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Song BH, Kim JM, Kim JK, Jang HS, Yun GN, Choi EJ, Song JY, Yun SI, Lee YM. Packaging of porcine reproductive and respiratory syndrome virus replicon RNA by a stable cell line expressing its nucleocapsid protein. J Microbiol 2011; 49:516-23. [PMID: 21717343 PMCID: PMC7091078 DOI: 10.1007/s12275-011-1280-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Accepted: 06/13/2011] [Indexed: 11/05/2022]
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV), a member of the Arteriviridae family, is one of the most common and economically important swine pathogens. Although both live-attenuated and killed-inactivated vaccines against the virus have been available for a decade, PRRSV is still a major problem in the swine industry worldwide. To explore the possibility of producing single-round infectious PRRSV replicon particles as a potential vaccine strategy, we have now generated two necessary components: 1) a stable cell line (BHK/Sinrepl9/PRRSV-N) that constitutively expresses the viral nucleocapsid (N) protein localized to the cytoplasm and the nucleolus and 2) a PRRSV replicon vector (pBAC/PRRSV/Replicon-AN) with a 177-nucleotide deletion, removing the 3′-half portion of ORF7 in the viral genome, from which the self-replicating propagation-defective replicon RNAs were synthesized in vitro by SP6 polymerase run-off transcription. Transfection of this replicon RNA into N protein-expressing BHK-21 cells led to the secretion of infectious particles that packaged the replicon RNA, albeit with a low production efficiency of 0.4 × 102 to 1.1 × 102 infectious units/ml; the produced particles had only single-round infectivity with no cell-to-cell spread. This trans-complementation system for PRRSV provides a useful platform for studies to define the packaging signals and motifs present within the viral genome and N protein, respectively, and to develop viral replicon-based antiviral vaccines that will stop the infection and spread of this pathogen.
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Affiliation(s)
- Byung-Hak Song
- Department of Microbiology, College of Medicine and Medical Research Institute, Chungbuk National University, Cheongju, 361-763, Republic of Korea
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Tan F, Wei Z, Li Y, Zhang R, Zhuang J, Sun Z, Yuan S. Identification of non-essential regions in nucleocapsid protein of porcine reproductive and respiratory syndrome virus for replication in cell culture. Virus Res 2011; 158:62-71. [PMID: 21440019 PMCID: PMC7114398 DOI: 10.1016/j.virusres.2011.03.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Revised: 03/12/2011] [Accepted: 03/14/2011] [Indexed: 01/03/2023]
Abstract
Nucleocapsid (N) protein of porcine reproductive and respiratory syndrome virus (PRRSV) plays a central role in virus replication. In this study, serial N- and C-terminal truncations of N protein were performed in the context of type 2 PRRSV infectious cDNA clone, and our results revealed that a stretch of inter-genotypic variable N terminal residues aa 5–13 (5NGKQQKKK13K) and the last four inter-genotypic variable aa residues (120SPS123A) at the C terminus of N protein were dispensable for type 2 PRRSV infectivity. All the recovered deletion mutant viruses had spontaneous mutations in the N coding region, including substitution, deletion and insertion. We re-engineered the additional internal deletion with or without the original C-terminal deletion back into wild-type APRRS and found that the internal domain spanning the inter-genotypic variable residues 39–42 (39KGP42G) and conserved residues 48–52 (48KNPE52K), respectively, were dispensable for type 2 PRRSV viability. These results demonstrated that N protein contains non-essential regions for virus viability in cell culture. Such dispensable regions could be utilized as insertion site for foreign tag expression and the rescued viruses could be the candidates for marker vaccine.
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Affiliation(s)
- Feifei Tan
- Department of Swine Infectious Diseases, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, No. 518 Ziyue Road, Shanghai 200241, China
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Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) is an enveloped, positive-sense single-stranded RNA virus belonging to the Arteriviridae family. Arteriviruses and coronaviruses are grouped together in the order Nidovirales, based on similarities in genome organization and expression strategy. Over the past decade, crystal structures of several viral proteins, electron microscopic studies of the virion, as well as biochemical and in vivo studies on protein-protein interactions have led to a greatly increased understanding of PRRSV structural biology. At this point, crystal structures are available for the viral proteases NSP1α, NSP1β and NSP4 and the nucleocapsid protein, N. The NSP1α and NSP1β structures have revealed additional non-protease domains that may be involved in modulation of host functions. The N protein forms a dimer with a novel fold so far only seen in PRRSV and other nidoviruses. Cryo-electron tomographic studies have shown the three-dimensional organization of the PRRSV virion and suggest that the viral nucleocapsid has an asymmetric, linear arrangement, rather than the isometric core previously described. Together, these studies have revealed a closer structural relationship between arteri- and coronaviruses than previously anticipated.
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Affiliation(s)
- Terje Dokland
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA.
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Song C, Krell P, Yoo D. Nonstructural protein 1α subunit-based inhibition of NF-κB activation and suppression of interferon-β production by porcine reproductive and respiratory syndrome virus. Virology 2010; 407:268-80. [PMID: 20850164 DOI: 10.1016/j.virol.2010.08.025] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Revised: 06/22/2010] [Accepted: 08/20/2010] [Indexed: 12/24/2022]
Abstract
Induction of type I interferon (IFN-α/β) is an early antiviral response of the host, and porcine reproductive and respiratory syndrome virus (PRRSV) has been reported to downregulate the IFN response during infection in cells and pigs. We report that the PRRSV nonstructural protein 1α (Nsp1α) subunit of Nsp1 is a nuclear-cytoplasmic protein distributed to the nucleus and contains a strong suppressive activity for IFN-β production that is mediated through the retinoic acid-inducible gene I (RIG-I) signaling pathway. Nsp1α suppressed the activation of nuclear factor (NF)-κB when stimulated with dsRNA or tumor necrosis factor (TNF)-α, and NF-κB suppression was RIG-I-dependent. The suppression of NF-κB activation was associated with the poor production of IFN-β during PRRSV infection. The C-terminal 14 amino acids of the Nsp1α subunit were critical in maintaining immunosuppressive activity of Nsp1α for both IFN-β and NF-κB, suggesting that the newly identified zinc finger configuration comprising of Met180 may be crucial for inhibitory activities. Nsp1α inhibited IκB phosphorylation and as a consequence NF-κB translocation to the nucleus was blocked, leading to the inhibition of NF-κB stimulated gene expression. Our results suggest that PRRSV Nsp1α is a multifunctional nuclear protein participating in the modulation of the host IFN system.
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Affiliation(s)
- Cheng Song
- Department of Pathobiology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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31
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Activation of NF-κB by nucleocapsid protein of the porcine reproductive and respiratory syndrome virus. Virus Genes 2010; 42:76-81. [DOI: 10.1007/s11262-010-0548-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Accepted: 10/25/2010] [Indexed: 10/18/2022]
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Yoo D, Song C, Sun Y, Du Y, Kim O, Liu HC. Modulation of host cell responses and evasion strategies for porcine reproductive and respiratory syndrome virus. Virus Res 2010; 154:48-60. [PMID: 20655963 PMCID: PMC7114477 DOI: 10.1016/j.virusres.2010.07.019] [Citation(s) in RCA: 119] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2010] [Revised: 06/24/2010] [Accepted: 07/18/2010] [Indexed: 12/13/2022]
Abstract
The immune surveillance system protects host cells from viral infection, and viruses have evolved to escape this system for efficient proliferation in the host. Host cells produce cytokines and chemokines in response to viral infection, and among such effector molecules, type I interferons are the principal antiviral cytokines and therefore effective targets for viruses to disarm host surveillance. Porcine reproductive and respiratory syndrome virus (PRRSV) expresses proteins that circumvent the IFN response and other cellular processes, and to compensate the small coding capacity of PRRSV, these proteins are multifunctional. To date, at least four viral proteins have been identified and studied as viral antagonists of host defenses: N as a structural protein and three non-structural proteins, Nsp1 (Nsp1α and Nsp1β), Nsp2, and Nsp11. Among these, N and Nsp1 are nuclear-cytoplasmic proteins distributed in both the nucleus and cytoplasm of cells. Nsp1 and Nsp2 are viral proteases while Nsp11 is an endoribonuclease. This review describes the current understanding of the role of these proteins in modulating the host innate immune responses. Blocking against virus-mediated inhibition of the innate response may lead to the future development of effective vaccines. The understanding of viral mechanisms modulating the normal cellular processes will be a key to the design of an effective control strategy for PRRS.
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Affiliation(s)
- Dongwan Yoo
- Department of Pathobiology, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61802, USA.
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The role of porcine reproductive and respiratory syndrome (PRRS) virus structural and non-structural proteins in virus pathogenesis. Anim Health Res Rev 2010; 11:135-63. [DOI: 10.1017/s1466252310000034] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
AbstractPorcine reproductive and respiratory syndrome (PRRS) is an economically devastating viral disease affecting the swine industry worldwide. The etiological agent, PRRS virus (PRRSV), possesses a RNA viral genome with nine open reading frames (ORFs). The ORF1a and ORF1b replicase-associated genes encode the polyproteins pp1a and pp1ab, respectively. The pp1a is processed in nine non-structural proteins (nsps): nsp1α, nsp1β, and nsp2 to nsp8. Proteolytic cleavage of pp1ab generates products nsp9 to nsp12. The proteolytic pp1a cleavage products process and cleave pp1a and pp1ab into nsp products. The nsp9 to nsp12 are involved in virus genome transcription and replication. The 3′ end of the viral genome encodes four minor and three major structural proteins. The GP2a, GP3and GP4(encoded by ORF2a, 3 and 4), are glycosylated membrane associated minor structural proteins. The fourth minor structural protein, the E protein (encoded by ORF2b), is an unglycosylated membrane associated protein. The viral envelope contains two major structural proteins: a glycosylated major envelope protein GP5(encoded by ORF5) and an unglycosylated membrane M protein (encoded by ORF6). The third major structural protein is the nucleocapsid N protein (encoded by ORF7). All PRRSV non-structural and structural proteins are essential for virus replication, and PRRSV infectivity is relatively intolerant to subtle changes within the structural proteins. PRRSV virulence is multigenic and resides in both the non-structural and structural viral proteins. This review discusses the molecular characteristics, biological and immunological functions of the PRRSV structural and nsps and their involvement in the virus pathogenesis.
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Puthenveetil S, Liu DS, White KA, Thompson S, Ting AY. Yeast display evolution of a kinetically efficient 13-amino acid substrate for lipoic acid ligase. J Am Chem Soc 2010; 131:16430-8. [PMID: 19863063 DOI: 10.1021/ja904596f] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Escherichia coli lipoic acid ligase (LplA) catalyzes ATP-dependent covalent ligation of lipoic acid onto specific lysine side chains of three acceptor proteins involved in oxidative metabolism. Our lab has shown that LplA and engineered mutants can ligate useful small-molecule probes such as alkyl azides ( Nat. Biotechnol. 2007 , 25 , 1483 - 1487 ) and photo-cross-linkers ( Angew. Chem., Int. Ed. 2008 , 47 , 7018 - 7021 ) in place of lipoic acid, facilitating imaging and proteomic studies. Both to further our understanding of lipoic acid metabolism, and to improve LplA's utility as a biotechnological platform, we have engineered a novel 13-amino acid peptide substrate for LplA. LplA's natural protein substrates have a conserved beta-hairpin structure, a conformation that is difficult to recapitulate in a peptide, and thus we performed in vitro evolution to engineer the LplA peptide substrate, called "LplA Acceptor Peptide" (LAP). A approximately 10(7) library of LAP variants was displayed on the surface of yeast cells, labeled by LplA with either lipoic acid or bromoalkanoic acid, and the most efficiently labeled LAP clones were isolated by fluorescence activated cell sorting. Four rounds of evolution followed by additional rational mutagenesis produced a "LAP2" sequence with a k(cat)/K(m) of 0.99 muM(-1) min(-1), >70-fold better than our previous rationally designed 22-amino acid LAP1 sequence (Nat. Biotechnol. 2007, 25, 1483-1487), and only 8-fold worse than the k(cat)/K(m) values of natural lipoate and biotin acceptor proteins. The kinetic improvement over LAP1 allowed us to rapidly label cell surface peptide-fused receptors with quantum dots.
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Affiliation(s)
- Sujiet Puthenveetil
- Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA
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Song C, Lu R, Bienzle D, Liu HC, Yoo D. Interaction of the porcine reproductive and respiratory syndrome virus nucleocapsid protein with the inhibitor of MyoD family-a domain-containing protein. Biol Chem 2009; 390:215-23. [PMID: 19090724 DOI: 10.1515/bc.2009.028] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Porcine reproductive and respiratory syndrome (PRRS) virus is an RNA virus that replicates in the cytoplasm, but the viral nucleocapsid (N) protein localizes specifically in the nucleus and nucleolus of virus-infected cells. Nuclear localization of N is non-essential for PRRSV replication in cultured cells but has been shown to modulate the pathogenesis of virus in pigs, suggesting that N plays an accessory role in the nucleus during infection. We identified by yeast two-hybrid screening the inhibitor of MyoD family-a (I-mfa) domain-containing protein (HIC) as a cellular partner for PRRS virus (PRRSV) N protein. This protein is a homolog of human HIC, a recently identified cellular transcription factor. The specific interaction of PRRSV N with HIC was confirmed in cells by mammalian two-hybrid assay and co-immunoprecipitation and in vitro by GST pull-down assay. HIC is a zinc-binding protein and confocal microscopy demonstrated co-localization of N with the HIC-p40 isomer in the nucleus and nucleolus, and in the cytoplasm with HIC-p32, which is the N-terminal truncation of HIC-p40. The porcine homolog of HIC is universally expressed in pig tissues including alveolar macrophages. The interaction of viral capsid with the cellular transcription factor implicates a possible regulation of host cell gene expression by the N protein during PRRSV infection.
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Affiliation(s)
- Cheng Song
- Department of Pathobiology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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Mohammadi H, Sharif S, Rowland RR, Yoo D. The lactate dehydrogenase-elevating virus capsid protein is a nuclear-cytoplasmic protein. Arch Virol 2009; 154:1071-80. [PMID: 19517211 PMCID: PMC7087266 DOI: 10.1007/s00705-009-0410-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2009] [Accepted: 05/25/2009] [Indexed: 12/17/2022]
Abstract
Arteriviruses replicate in the cytoplasm and do not require the nucleus function for virus multiplication in vitro. However, nucleocapsid (N) protein of two arteriviruses, porcine reproductive respiratory syndrome virus and equine arteritis virus, has been observed to localize in the nucleus and nucleolus of virus-infected and N-gene-transfected cells in addition to their normal cytoplasmic distribution. In the present study, the N protein of lactate dehydrogenase-elevating virus (LDV) of mice was examined for nuclear localization. The subcellular localization of LDV-N was determined by tagging N with enhanced green fluorescence protein (EGFP) at the N- and C-terminus. Both N-EGFP and EGFP-N fusion proteins localized to the nucleus and nucleolus of gene-transfected cells. Labeled N also accumulated in the perinuclear region, the site of virus replication. The LDV-N sequence contains a putative ‘pat4’-type nuclear localization signal (NLS) consisting of 38-KKKK. To determine its functional significance, a series of deletion constructs of N were generated and individually expressed in cells. The results showed that the ‘pat4’ NLS was essential for nuclear translocation. In addition, the LDV-N interacted with the importin-α and -β proteins, suggesting that the LDV-N nuclear localization may occur via the importin-mediated nuclear transport pathway. These results provide further evidence for the nuclear localization of N as a common feature within the arteriviruses.
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Emmott E, Hiscox JA. Nucleolar targeting: the hub of the matter. EMBO Rep 2009; 10:231-8. [PMID: 19229283 DOI: 10.1038/embor.2009.14] [Citation(s) in RCA: 218] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2008] [Accepted: 01/26/2009] [Indexed: 11/09/2022] Open
Abstract
The nucleolus is a dynamic structure that has roles in various processes, from ribosome biogenesis to regulation of the cell cycle and the cellular stress response. Such functions are frequently mediated by the sequestration or release of nucleolar proteins. Our understanding of protein targeting to the nucleolus is much less complete than our knowledge of membrane-spanning translocation systems--such as those involved in nuclear targeting--and the experimental evidence reveals that few parallels exist with these better-characterized systems. Here, we discuss the current understanding of nucleolar targeting, explore the types of sequence that control the localization of a protein to the nucleolus, and speculate that certain subsets of nucleolar proteins might act as hub proteins that are able to bind to multiple protein targets. In parallel to other subnuclear structures, such as PML bodies, the proteins that are involved in the formation and maintenance of the nucleolus are inexorably linked to nucleolar trafficking.
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Affiliation(s)
- Edward Emmott
- Institute of Molecular and Cellular Biology, Faculty of Biological Sciences, Garstang Building, University of Leeds, Leeds LS2 9JT, England, UK
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You JH, Howell G, Pattnaik AK, Osorio FA, Hiscox JA. A model for the dynamic nuclear/nucleolar/cytoplasmic trafficking of the porcine reproductive and respiratory syndrome virus (PRRSV) nucleocapsid protein based on live cell imaging. Virology 2008; 378:34-47. [PMID: 18550142 PMCID: PMC7103367 DOI: 10.1016/j.virol.2008.04.037] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2008] [Revised: 03/07/2008] [Accepted: 04/19/2008] [Indexed: 01/09/2023]
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV), an arterivirus, in common with many other positive strand RNA viruses, encodes a nucleocapsid (N) protein which can localise not only to the cytoplasm but also to the nucleolus in virus-infected cells and cells over-expressing N protein. The dynamic trafficking of positive strand RNA virus nucleocapsid proteins and PRRSV N protein in particular between the cytoplasm and nucleolus is unknown. In this study live imaging of permissive and non-permissive cell lines, in conjunction with photo-bleaching (FRAP and FLIP), was used to investigate the trafficking of fluorescent labeled (EGFP) PRRSV-N protein. The data indicated that EGFP-PRRSV-N protein was not permanently sequestered to the nucleolus and had equivalent mobility to cellular nucleolar proteins. Further the nuclear import of N protein appeared to occur faster than nuclear export, which may account for the observed relative distribution of N protein between the cytoplasm and the nucleolus.
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Affiliation(s)
- Jae-Hwan You
- Institute of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK
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Pei Y, Hodgins DC, Lee C, Calvert JG, Welch SKW, Jolie R, Keith M, Yoo D. Functional mapping of the porcine reproductive and respiratory syndrome virus capsid protein nuclear localization signal and its pathogenic association. Virus Res 2008; 135:107-14. [PMID: 18403041 DOI: 10.1016/j.virusres.2008.02.012] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2008] [Revised: 02/20/2008] [Accepted: 02/22/2008] [Indexed: 11/15/2022]
Abstract
PRRSV (porcine reproductive and respiratory syndrome virus) nucleocapsid (N) protein is the most abundant structural protein of the virus. During infection, the N protein is specifically localized to the nucleus and nucleolus in addition to its normal cytoplasmic distribution. Previously, a nuclear localization signal (NLS, 41-PGKK(N/S)KKKN)-null mutant virus (41-PGGGNKKKN) showed reduced viremia and increased production of neutralizing antibodies in infected pigs. However, the mutagenized NLS underwent strong selection pressure in the pig that resulted in partial or complete reversion and reacquisition of NLS function, and thus the biological effect of the NLS-null mutation needed further investigation. In the present study, a total of 9 "reversion resistant" mutants were generated by amino acid deletions and substitutions using an infectious cDNA clone. Two mutant clones (PG--SKKKS and PG--S-KKS) that produced progeny viruses were genetically stable for at least 20 passages in cell culture. Infection of pigs with those mutants induced neutralizing antibodies to higher titers than with wild-type virus. Both mutant viruses induced viremia of lower titer and of shorter duration than wild-type virus. RT-PCR from tonsils showed that both mutants persisted at a reduced level. Virus transmission to contact pigs was also lower in the mutant virus infected groups. No reversion to functional NLS was detected in either mutant from any pig. These data demonstrate that N protein nuclear localization is indeed associated with viral pathogenesis and host response to PRRS.
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Affiliation(s)
- Yanlong Pei
- Department of Pathobiology, University of Guelph, Guelph, Ontario, Canada
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40
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Reed ML, Howell G, Harrison SM, Spencer KA, Hiscox JA. Characterization of the nuclear export signal in the coronavirus infectious bronchitis virus nucleocapsid protein. J Virol 2007; 81:4298-304. [PMID: 17202223 PMCID: PMC1866115 DOI: 10.1128/jvi.02239-06] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2006] [Accepted: 12/27/2006] [Indexed: 01/13/2023] Open
Abstract
The nucleocapsid (N) protein of infectious bronchitis virus (IBV) localizes to the cytoplasm and nucleolus and contains an eight-amino-acid nucleolar retention motif. In this study, a leucine-rich nuclear export signal (NES) (291-LQLDGLHL-298) present in the C-terminal region of the IBV N protein was analyzed by using alanine substitution and deletion mutagenesis to investigate the relative contributions that leucine residues make to nuclear export and where these residues are located on the structure of the IBV N protein. The analysis indicated that Leu296 and Leu298 are required for efficient nuclear export of the protein. Structural information indicated that both of these amino acids are available for interaction with protein complexes involved in this process. However, export of N protein from the nucleus/nucleolus was not inhibited by leptomycin B treatment, indicating that N protein nuclear export is independent of the CRM1-mediated export pathway.
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Affiliation(s)
- Mark L Reed
- Institute of Molecular and Cellular Biology, Faculty of Biology Sciences, Garstang Building, University of Leeds, Leeds LS2 6JT, United Kingdom
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Abstract
The nucleolus is a dynamic subnuclear structure that is crucial to the successful functioning of a cell. Its functions include ribosomal RNA synthesis, cell growth and cell-cycle control as well as responding to cellular stress. Recent studies show that the nucleolus is not a steady-state structure but instead is made up of numerous protein–protein and protein–nucleic-acid interactions that are constantly changing in response to the metabolic conditions of the cell. Many different viruses target the nucleolus to disrupt host-cell function and to recruit cellular proteins to aid in virus replication. The study of viral-protein trafficking to the nucleolus and the interaction of viral proteins with nucleolar proteins is providing many insights into the cell biology of the nucleolus. Because the nucleolus is fundamental to the life cycle of many viruses, disrupting the interaction between the nucleolus and the virus could lead to the design of novel therapeutic strategies.
RNA viruses, particularly positive-strand RNA viruses, interact with the nucleolus to usurp host-cell functions and recruit nucleolar proteins to facilitate virus replication. Here, Julian Hiscox reviews the latest data on RNA-virus interactions with this dynamic subnuclear structure. The nucleolus is a dynamic subnuclear structure with roles in ribosome subunit biogenesis, mediation of cell-stress responses and regulation of cell growth. The proteome and structure of the nucleolus are constantly changing in response to metabolic conditions. RNA viruses interact with the nucleolus to usurp host-cell functions and recruit nucleolar proteins to facilitate virus replication. Investigating the interactions between RNA viruses and the nucleolus will facilitate the design of novel anti-viral therapies, such as recombinant vaccines and therapeutic molecular interventions, and also contribute to a more detailed understanding of the cell biology of the nucleolus.
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Affiliation(s)
- Julian A Hiscox
- Institute of Molecular and Cellular Biology, Faculty of Biological Sciences, and Astbury Centre for Structural Molecular Biology, Garstang Building, University of Leeds, Leeds, LS2 9JT, UK.
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Reed ML, Dove BK, Jackson RM, Collins R, Brooks G, Hiscox JA. Delineation and modelling of a nucleolar retention signal in the coronavirus nucleocapsid protein. Traffic 2006; 7:833-48. [PMID: 16734668 PMCID: PMC7488588 DOI: 10.1111/j.1600-0854.2006.00424.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Unlike nuclear localization signals, there is no obvious consensus sequence for the targeting of proteins to the nucleolus. The nucleolus is a dynamic subnuclear structure which is crucial to the normal operation of the eukaryotic cell. Studying nucleolar trafficking signals is problematic as many nucleolar retention signals (NoRSs) are part of classical nuclear localization signals (NLSs). In addition, there is no known consensus signal with which to inform a study. The avian infectious bronchitis virus (IBV), coronavirus nucleocapsid (N) protein, localizes to the cytoplasm and the nucleolus. Mutagenesis was used to delineate a novel eight amino acid motif that was necessary and sufficient for nucleolar retention of N protein and colocalize with nucleolin and fibrillarin. Additionally, a classical nuclear export signal (NES) functioned to direct N protein to the cytoplasm. Comparison of the coronavirus NoRSs with known cellular and other viral NoRSs revealed that these motifs have conserved arginine residues. Molecular modelling, using the solution structure of severe acute respiratory (SARS) coronavirus N‐protein, revealed that this motif is available for interaction with cellular factors which may mediate nucleolar localization. We hypothesise that the N‐protein uses these signals to traffic to and from the nucleolus and the cytoplasm.
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Affiliation(s)
- Mark L. Reed
- Institute of Molecular and Cellular Biology, University of Leeds, Leeds, UK
| | - Brian K. Dove
- Institute of Molecular and Cellular Biology, University of Leeds, Leeds, UK
| | - Richard M. Jackson
- Institute of Molecular and Cellular Biology, University of Leeds, Leeds, UK
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
| | - Rebecca Collins
- Institute of Molecular and Cellular Biology, University of Leeds, Leeds, UK
| | - Gavin Brooks
- School of Pharmacy, University of Reading, Reading, UK
| | - Julian A. Hiscox
- Institute of Molecular and Cellular Biology, University of Leeds, Leeds, UK
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
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Perlman S, Holmes KV. The nuclear localization signal of the PRRS virus nucleocapsid protein viral replication in vitro and antibody response in vivo. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2006; 581:145-8. [PMID: 17037521 PMCID: PMC7124060 DOI: 10.1007/978-0-387-33012-9_25] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Affiliation(s)
- Stanley Perlman
- Department of Pediatrics, University of Iowa, 52242 Iowa City, IA USA
| | - Kathryn V. Holmes
- Department of Microbiology, University of Colorado Health Sciences Center at Fitzsimons, 80045-8333 Aurora, CO USA
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Lee C, Hodgins D, Calvert JG, Welch SKW, Jolie R, Yoo D. Mutations within the nuclear localization signal of the porcine reproductive and respiratory syndrome virus nucleocapsid protein attenuate virus replication. Virology 2005; 346:238-50. [PMID: 16330065 PMCID: PMC7172752 DOI: 10.1016/j.virol.2005.11.005] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2005] [Revised: 09/27/2005] [Accepted: 11/04/2005] [Indexed: 11/17/2022]
Abstract
Porcine reproductive and respiratory syndrome virus (PRRSV) is an RNA virus replicating in the cytoplasm, but the nucleocapsid (N) protein is specifically localized to the nucleus and nucleolus in virus-infected cells. A 'pat7' motif of 41-PGKK(N/S)KK has previously been identified in the N protein as the functional nuclear localization signal (NLS); however, the biological consequences of N protein nuclear localization are unknown. In the present study, the role of N protein nuclear localization during infection was investigated in pigs using an NLS-null mutant virus. When two lysines at 43 and 44 at the NLS locus were substituted to glycines, the modified NLS with 41-PGGGNKK restricted the N protein to the cytoplasm. This NLS-null mutation was introduced into a full-length infectious cDNA clone of PRRSV. Upon transfection of cells, the NLS-null full-length clone induced cytopathic effects and produced infectious progeny. The NLS-null virus grew to a titer 100-fold lower than that of wild-type virus. To examine the response to NLS-null PRRSV in the natural host, three groups of pigs, consisting of seven animals per group, were intranasally inoculated with wild-type, placebo, or NLS-null virus, and the animals were maintained for 4 weeks. The NLS-null-infected pigs had a significantly shorter mean duration of viremia than wild-type-infected pigs but developed significantly higher titers of neutralizing antibodies. Mutations occurred at the NLS locus in one pig during viremia, and four types of mutations were identified: 41-PGRGNKK, 41-PGGRNKK, and 41-PGRRNKK, and 41-PGKKSKK. Both wild-type and NLS-null viruses persisted in the tonsils for at least 4 weeks, and the NLS-null virus persisting in the tonsils was found to be mutated to either 41-PGRGNKK or 41-PGGRNKK in all pigs. No other mutation was found in the N gene. All types of reversions which occurred during viremia and persistence were able to translocate the mutated N proteins to the nucleus, indicating a strong selection pressure for reversion at the NLS locus of the N protein in vivo. Reversions from NLS-null to functional NLS in the tonsils suggest a possible correlation of viral persistence with N protein nuclear localization. These results show that N protein nuclear localization is non-essential for PRRSV multiplication but may play an important role in viral attenuation and in pathogenesis in vivo.
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Affiliation(s)
- Changhee Lee
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Douglas Hodgins
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | | | | | - Rika Jolie
- Pfizer Animal Health, Kalamazoo, MI 49001, USA
| | - Dongwan Yoo
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada N1G 2W1
- Corresponding author. Fax: +1 519 824 5930.
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Libault M, Tessadori F, Germann S, Snijder B, Fransz P, Gaudin V. The Arabidopsis LHP1 protein is a component of euchromatin. PLANTA 2005; 222:910-25. [PMID: 16244868 DOI: 10.1007/s00425-005-0129-4] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2005] [Accepted: 08/29/2005] [Indexed: 05/05/2023]
Abstract
The HP1 family proteins are involved in several aspects of chromatin function and regulation in Drosophila, mammals and the fission yeast. Here we investigate the localization of LHP1, the unique Arabidopsis thaliana HP1 homolog known at present time, to approach its function. A functional LHP1-GFP fusion protein, able to restore the wild-type phenotype in the lhp1 mutant, was used to analyze the subnuclear distribution of LHP1 in both A. thaliana and Nicotiana tabacum. In A. thaliana interphase nuclei, LHP1 was predominantly located outside the heterochromatic chromocenters. No major aberrations were observed in heterochromatin content or chromocenter organization in lhp1 plants. These data indicate that LHP1 is mainly involved in euchromatin organization in A. thaliana. In tobacco BY-2 cells, the LHP1 distribution, although in foci, slightly differed suggesting that LHP1 localization is determined by the underlying genome organization of plant species. Truncated LHP1 proteins expressed in vivo allowed us to determine the function of the different segments in the localization. The in foci distribution is dependent on the presence of the two chromo domains, whereas the hinge region has some nucleolus-targeting properties. Furthermore, like the animal HP1beta and HP1gamma subtypes, LHP1 dissociates from chromosomes during mitosis. In transgenic plants expressing the LHP1-GFP fusion protein, two major localization patterns were observed according to cell types suggesting that localization evolves with age or differentiation states. Our results show conversed characteristics of the A. thaliana HP1 homolog with the mammal HP1gamma isoform, besides specific plant properties.
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Affiliation(s)
- Marc Libault
- Laboratoire de Biologie Cellulaire, IJPB, INRA, route de St Cyr, 78026, Versailles Cedex, France
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Rowland RRR, Chauhan V, Fang Y, Pekosz A, Kerrigan M, Burton MD. Intracellular localization of the severe acute respiratory syndrome coronavirus nucleocapsid protein: absence of nucleolar accumulation during infection and after expression as a recombinant protein in vero cells. J Virol 2005; 79:11507-12. [PMID: 16103202 PMCID: PMC1193611 DOI: 10.1128/jvi.79.17.11507-11512.2005] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The nucleocapsid (N) protein of several members within the order Nidovirales localizes to the nucleolus during infection and after transfection of cells with N genes. However, confocal microscopy of N protein localization in Vero cells infected with the severe acute respiratory syndrome coronavirus (SARS-CoV) or transfected with the SARS-CoV N gene failed to show the presence of N in the nucleoplasm or nucleolus. Amino acids 369 to 389, which contain putative nuclear localization signal (NLS) and nucleolar localization signal motifs, failed to restore nuclear localization to an NLS-minus mutant Rev protein. These data indicate that nuclear localization is not a conserved property among all nidoviruses.
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Affiliation(s)
- Raymond R R Rowland
- Diagnostic Medicine and Pathobiology, Kansas State University, Manhattan, 66506, USA.
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Rowland RRR, Yoo D. Nucleolar-cytoplasmic shuttling of PRRSV nucleocapsid protein: a simple case of molecular mimicry or the complex regulation by nuclear import, nucleolar localization and nuclear export signal sequences. Virus Res 2003; 95:23-33. [PMID: 12921993 PMCID: PMC7127199 DOI: 10.1016/s0168-1702(03)00161-8] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The order Nidovirales, which includes the arteriviruses and coronaviruses, incorporate a cytoplasmic replication scheme; however, the nucleocapsid (N) protein of several members of this group localizes to the nucleolus suggesting that viral proteins influence nuclear processes during replication. The relatively small, 123 amino acid, N protein of porcine reproductive and respiratory syndrome virus (PRRSV), an arterivirus, presents an ideal model system for investigating the properties and mechanism of N protein nucleolar localization. The PRRSV N protein is found in both cytoplasmic and nucleolar compartments during infection and after transfection of gene constructs that express N-enhanced green fluorescent protein (EGFP) fusion proteins. Experiments using oligopeptides, truncated polypeptides and amino acid-substituted proteins have identified several domains within PRRSV N protein that participate in nucleo-cytoplasmic shuttling, including a cryptic nuclear localization signal (NLS) called NLS-1, a functional NLS (NLS-2), a nucleolar localization sequence (NoLS), as well as a possible nuclear export signal (NES). The purpose of this paper is to review our current understanding of PRRSV N protein shuttling and propose a shuttling scheme regulated by RNA binding and post-translational modification.
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Affiliation(s)
- Raymond R R Rowland
- Department of Diagnostic Medicine and Pathobiology, Kansas State University, Manhattan, KS 66506, USA.
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