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Huang S, Huang Y, Su T, Huang R, Su L, Wu Y, Weng S, He J, Xie J. Orange-spotted grouper nervous necrosis virus-encoded protein A induces interferon expression via RIG-I/MDA5-MAVS-TBK1-IRF3 signaling in fish cells. Microbiol Spectr 2024; 12:e0453222. [PMID: 38095472 PMCID: PMC10783131 DOI: 10.1128/spectrum.04532-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 11/20/2023] [Indexed: 01/13/2024] Open
Abstract
IMPORTANCE As a major pathogen, nervous necrosis virus (NNV) infects more than 120 fish species worldwide and is virulent to larvae and juvenile fish, hampering the development of the fish fry industry. Understanding virus-host interaction and underlying mechanisms is an important but largely unknown issue in fish virus studies. Here, using channel catfish ovary and fathead minnow cells as models for the study of innate immunity signaling, we found that NNV-encoded ProA activated interferon signaling via the retinoic acid-inducible gene I (RIG-I)-like receptor (RLR) pathway which was still suppressed by the infection of wild-type NNV. This finding has important implications for the comprehension of NNV protein function and the immune response from different cells. First, RIG-I is the key node for anti-NNV innate immunity. Second, the response intensity of RLR signaling determines the degree of NNV proliferation. This study expands our knowledge regarding the overview of signal pathways affected by NNV-encoded protein and also highlights potential directions for the control of aquatic viruses.
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Affiliation(s)
- Siyou Huang
- State Key Laboratory of Biocontrol, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), China-ASEAN Belt and Road Joint Laboratory on Mariculture Technology, Guangdong Provincial Key Laboratory of Aquatic Economic Animals, Sun Yat-sen University, Guangzhou, China
| | - Yi Huang
- State Key Laboratory of Biocontrol, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), China-ASEAN Belt and Road Joint Laboratory on Mariculture Technology, Guangdong Provincial Key Laboratory of Aquatic Economic Animals, Sun Yat-sen University, Guangzhou, China
| | - Taowen Su
- State Key Laboratory of Biocontrol, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), China-ASEAN Belt and Road Joint Laboratory on Mariculture Technology, Guangdong Provincial Key Laboratory of Aquatic Economic Animals, Sun Yat-sen University, Guangzhou, China
| | - Runqing Huang
- School of Life Science, Huizhou University, Huizhou, China
| | - Lianpan Su
- State Key Laboratory of Biocontrol, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), China-ASEAN Belt and Road Joint Laboratory on Mariculture Technology, Guangdong Provincial Key Laboratory of Aquatic Economic Animals, Sun Yat-sen University, Guangzhou, China
| | - Yujia Wu
- State Key Laboratory of Biocontrol, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), China-ASEAN Belt and Road Joint Laboratory on Mariculture Technology, Guangdong Provincial Key Laboratory of Aquatic Economic Animals, Sun Yat-sen University, Guangzhou, China
| | - Shaoping Weng
- State Key Laboratory of Biocontrol, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), China-ASEAN Belt and Road Joint Laboratory on Mariculture Technology, Guangdong Provincial Key Laboratory of Aquatic Economic Animals, Sun Yat-sen University, Guangzhou, China
| | - Jianguo He
- State Key Laboratory of Biocontrol, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), China-ASEAN Belt and Road Joint Laboratory on Mariculture Technology, Guangdong Provincial Key Laboratory of Aquatic Economic Animals, Sun Yat-sen University, Guangzhou, China
| | - Junfeng Xie
- State Key Laboratory of Biocontrol, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), China-ASEAN Belt and Road Joint Laboratory on Mariculture Technology, Guangdong Provincial Key Laboratory of Aquatic Economic Animals, Sun Yat-sen University, Guangzhou, China
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2
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Qin Y, Zhang P, Deng S, Guo W, Zhang M, Liu H, Qiu R, Yao L. Red-grouper nervous necrosis virus B1 protein inhibits fish IFN response by targeting Ser5-phosphorylated RNA polymerase II to promote viral replication. FISH & SHELLFISH IMMUNOLOGY 2023; 134:108578. [PMID: 36740084 DOI: 10.1016/j.fsi.2023.108578] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Revised: 01/15/2023] [Accepted: 02/02/2023] [Indexed: 06/18/2023]
Abstract
Nervous necrosis virus (NNV) could infect more than 200 fish species worldwide, with almost 100% mortality in affected larvae and juvenile fish. Among different genotypes of NNV, the red-grouper nervous necrosis virus (RGNNV) genotype is the most widely reported with the highest number of susceptible species. Interferon (IFN) is a crucial antiviral cytokine and RGNNV needs to develop some efficient strategies to resist host IFN-stimulated antiviral immune. Although considerable researches on RGNNV, whether RGNNV B1 protein participates in regulating the host's IFN response remains unknown. Here, we reported that B1 protein acted as a transcript inhibition factor to suppress fish IFN production. We firstly found that ectopic expression of B1 protein significantly decreased IFN and IFN-stimulated genes (ISGs) mRNA levels and IFNφ1 promoter activity induced by polyinosinic:polycytidylic acid [poly (I:C)]. Further studies showed that B1 protein inhibited the IFNφ1 promoter activity stimulated by the key RIG-I-like receptors (RLRs) factors, including MDA5, MAVS, TBK1, IRF3, and IRF7 and decreased their protein levels. Moreover, B1 protein significantly inhibited the activity of constitutively active cytomegalovirus (CMV) promoter, which suggested that B1 protein was a transcription inhibitor. Western blot indicated that B1 protein decreased the Ser5 phosphorylation of RNA polymerase II (RNAP II) C-terminal domain (CTD). Together, our data demonstrated that RGNNV B1 protein was a host transcript antagonist, which intervened RNAP II Ser5-phosphorylation, inhibiting host IFN response and facilitating RGNNV replication.
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Affiliation(s)
- Yinghui Qin
- College of Life Science and Agricultural Engineering, Nanyang Normal University, Nanyang, 473061, China; Key Laboratory of Ecological Security and Collaborative Innovation Centre of Water Security for Water Source Region of Mid-line of South-to-North Diversion Project of Henan Province, Nanyang, 473061, China; Henan Provincal Engineering and Technology Center of Health Products for Livestock and Poultry, Nanyang, 473061, China
| | - Peipei Zhang
- College of Life Science and Agricultural Engineering, Nanyang Normal University, Nanyang, 473061, China; Key Laboratory of Ecological Security and Collaborative Innovation Centre of Water Security for Water Source Region of Mid-line of South-to-North Diversion Project of Henan Province, Nanyang, 473061, China; Henan Provincal Engineering and Technology Center of Health Products for Livestock and Poultry, Nanyang, 473061, China
| | - Si Deng
- College of Life Science and Agricultural Engineering, Nanyang Normal University, Nanyang, 473061, China; Key Laboratory of Ecological Security and Collaborative Innovation Centre of Water Security for Water Source Region of Mid-line of South-to-North Diversion Project of Henan Province, Nanyang, 473061, China; Henan Provincal Engineering and Technology Center of Health Products for Livestock and Poultry, Nanyang, 473061, China
| | - Wenjing Guo
- College of Life Science and Agricultural Engineering, Nanyang Normal University, Nanyang, 473061, China; Key Laboratory of Ecological Security and Collaborative Innovation Centre of Water Security for Water Source Region of Mid-line of South-to-North Diversion Project of Henan Province, Nanyang, 473061, China; Henan Provincal Engineering and Technology Center of Health Products for Livestock and Poultry, Nanyang, 473061, China
| | - Mengfan Zhang
- College of Life Science and Agricultural Engineering, Nanyang Normal University, Nanyang, 473061, China; Key Laboratory of Ecological Security and Collaborative Innovation Centre of Water Security for Water Source Region of Mid-line of South-to-North Diversion Project of Henan Province, Nanyang, 473061, China; Henan Provincal Engineering and Technology Center of Health Products for Livestock and Poultry, Nanyang, 473061, China
| | - Haixiang Liu
- College of Life Science and Agricultural Engineering, Nanyang Normal University, Nanyang, 473061, China; Key Laboratory of Ecological Security and Collaborative Innovation Centre of Water Security for Water Source Region of Mid-line of South-to-North Diversion Project of Henan Province, Nanyang, 473061, China; Henan Provincal Engineering and Technology Center of Health Products for Livestock and Poultry, Nanyang, 473061, China
| | - Reng Qiu
- College of Life Science and Agricultural Engineering, Nanyang Normal University, Nanyang, 473061, China; Key Laboratory of Ecological Security and Collaborative Innovation Centre of Water Security for Water Source Region of Mid-line of South-to-North Diversion Project of Henan Province, Nanyang, 473061, China; Henan Provincal Engineering and Technology Center of Health Products for Livestock and Poultry, Nanyang, 473061, China
| | - Lunguang Yao
- College of Life Science and Agricultural Engineering, Nanyang Normal University, Nanyang, 473061, China; Key Laboratory of Ecological Security and Collaborative Innovation Centre of Water Security for Water Source Region of Mid-line of South-to-North Diversion Project of Henan Province, Nanyang, 473061, China; Henan Provincal Engineering and Technology Center of Health Products for Livestock and Poultry, Nanyang, 473061, China.
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3
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García-Álvarez MÁ, Arizcun M, Chaves-Pozo E, Cuesta A. Profile of Innate Immunity in Gilthead Seabream Larvae Reflects Mortality upon Betanodavirus Reassortant Infection and Replication. Int J Mol Sci 2022; 23:ijms23095092. [PMID: 35563482 PMCID: PMC9105140 DOI: 10.3390/ijms23095092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 04/28/2022] [Accepted: 04/29/2022] [Indexed: 12/10/2022] Open
Abstract
Historically, gilthead seabream (Sparus aurata) has been considered a fish species resistant to nervous necrosis virus (NNV) disease. Nevertheless, mortality in seabream hatcheries, associated with typical clinical signs of the viral encephalopathy and retinopathy (VER) disease has been confirmed to be caused by RGNNV/SJNNV reassortants. Because of this, seabream larvae at 37 and 86 days post-hatching (dph) were infected by immersion with RGNNV/SJNNV and SJNNV/RGNNV reassortants under laboratory conditions, and mortality, viral replication and immunity were evaluated. Our results show that gilthead seabream larvae, mainly those at 37 dph, are susceptible to infection with both NNV reassortant genotypes, with the highest impact from the RGNNV/SJNNV reassortant. In addition, viral replication occurs at both ages (37 and 86 dph) but the recovery of infective particles was only confirmed in 37 dph larvae,; this value was also highest with the RGNNV/SJNNV reassortant. Larvae immunity, including the expression of antiviral, inflammatory and cell-mediated cytotoxicity genes, was affected by NNV infection. Levels of the natural killer lysin (Nkl) peptide were increased in SJNNV/RGNNV-infected larvae of 37 dph, though hepcidin was not. Our results demonstrate that the seabream larvae are susceptible to both NNV reassortants, though mainly to RGNNV/SJNNV, in an age-dependent manner.
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Affiliation(s)
- Miguel Ángel García-Álvarez
- Immunobiology for Aquaculture Group, Department of Cell Biology and Histology, Faculty of Biology, Regional Campus of International Excellence “Campus Mare Nostrum”, University of Murcia, 30100 Murcia, Spain;
| | - Marta Arizcun
- Oceanographic Center of Murcia, Spanish Institute of Oceanography, Spanish National Research Council (IEO-CSIC), Carretera de la Azohía s/n. Puerto de Mazarrón, 30860 Murcia, Spain; (M.A.); (E.C.-P.)
| | - Elena Chaves-Pozo
- Oceanographic Center of Murcia, Spanish Institute of Oceanography, Spanish National Research Council (IEO-CSIC), Carretera de la Azohía s/n. Puerto de Mazarrón, 30860 Murcia, Spain; (M.A.); (E.C.-P.)
| | - Alberto Cuesta
- Immunobiology for Aquaculture Group, Department of Cell Biology and Histology, Faculty of Biology, Regional Campus of International Excellence “Campus Mare Nostrum”, University of Murcia, 30100 Murcia, Spain;
- Correspondence:
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4
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VNN disease and status of breeding for resistance to NNV in aquaculture. AQUACULTURE AND FISHERIES 2022. [DOI: 10.1016/j.aaf.2021.04.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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5
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Liu J, Qin Q, Zhang X, Li C, Yu Y, Huang X, Mukama O, Zeng L, Wang S. Development of a Novel Lateral Flow Biosensor Combined With Aptamer-Based Isolation: Application for Rapid Detection of Grouper Nervous Necrosis Virus. Front Microbiol 2020; 11:886. [PMID: 32508768 PMCID: PMC7249735 DOI: 10.3389/fmicb.2020.00886] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 04/16/2020] [Indexed: 01/07/2023] Open
Abstract
Nervous necrosis virus (NNV) has infected more than 50 fish species worldwide, and has caused serious economic losses in the aquaculture industries. However, there is no effective antiviral therapy. The development of a rapid and accurate point-of-care diagnostic method for the prevention and control of NNV infection is urgently required. Commonly used methods for NNV detection include the cell culture-based assay, antibody-based assay and polymerase chain reaction (PCR)-based assay. However, these methods have disadvantages as they are time-consuming and complex. In the present study, we developed a simple and sensitive aptamer-based lateral flow biosensor (LFB) method for the rapid detection of red-spotted grouper nervous necrosis virus (RGNNV). An aptamer is a single-stranded nucleotide, which can specifically bind to the target and has many advantages. Based on a previously selected aptamer, which specifically bound to the coat protein of RGNNV (RGNNV-CP), two modified aptamers were used in this study. One aptamer was used for magnetic bead enrichment and the other was used for isothermal strand displacement amplification (SDA). After amplification, the product was further tested by the LFB, and the detection results were observed by the naked eye within 5 min with high specificity and sensitivity. The LFB method could detect RGNNV-CP protein as low as 5 ng/mL or 5 × 103 RGNNV-infected GB (grouper brain) cells. Overall, it is the first application of a LFB combined with aptamer in the rapid diagnosis of virus from aquatic animals, which provides a new option for virus detection in aquaculture.
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Affiliation(s)
- Jiaxin Liu
- Joint Laboratory of Guangdong Province and Hong Kong Region on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China Agricultural University, Guangzhou, China
| | - Qiwei Qin
- Joint Laboratory of Guangdong Province and Hong Kong Region on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Marine Sciences, South China Agricultural University, Guangzhou, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Xinyue Zhang
- Joint Laboratory of Guangdong Province and Hong Kong Region on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China Agricultural University, Guangzhou, China
| | - Chen Li
- Joint Laboratory of Guangdong Province and Hong Kong Region on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China Agricultural University, Guangzhou, China
| | - Yepin Yu
- Joint Laboratory of Guangdong Province and Hong Kong Region on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Marine Sciences, South China Agricultural University, Guangzhou, China
| | - Xiaohong Huang
- Joint Laboratory of Guangdong Province and Hong Kong Region on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Marine Sciences, South China Agricultural University, Guangzhou, China
| | - Omar Mukama
- Key Laboratory of Regenerative Biology, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, China
| | - Lingwen Zeng
- School of Food Science and Engineering, Foshan University, Foshan, China
| | - Shaowen Wang
- Joint Laboratory of Guangdong Province and Hong Kong Region on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China Agricultural University, Guangzhou, China
- Guangdong Laboratory for Lingnan Modern Agriculture, College of Marine Sciences, South China Agricultural University, Guangzhou, China
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6
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Betanodavirus and VER Disease: A 30-year Research Review. Pathogens 2020; 9:pathogens9020106. [PMID: 32050492 PMCID: PMC7168202 DOI: 10.3390/pathogens9020106] [Citation(s) in RCA: 116] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 01/22/2020] [Accepted: 02/04/2020] [Indexed: 12/18/2022] Open
Abstract
The outbreaks of viral encephalopathy and retinopathy (VER), caused by nervous necrosis virus (NNV), represent one of the main infectious threats for marine aquaculture worldwide. Since the first description of the disease at the end of the 1980s, a considerable amount of research has gone into understanding the mechanisms involved in fish infection, developing reliable diagnostic methods, and control measures, and several comprehensive reviews have been published to date. This review focuses on host–virus interaction and epidemiological aspects, comprising viral distribution and transmission as well as the continuously increasing host range (177 susceptible marine species and epizootic outbreaks reported in 62 of them), with special emphasis on genotypes and the effect of global warming on NNV infection, but also including the latest findings in the NNV life cycle and virulence as well as diagnostic methods and VER disease control.
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7
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Souto S, Vázquez-Salgado L, Olveira JG, Bandín I. Amino acidic substitutions in the polymerase N-terminal region of a reassortant betanodavirus strain causing poor adaptation to temperature increase. Vet Res 2019; 50:50. [PMID: 31227007 PMCID: PMC6588924 DOI: 10.1186/s13567-019-0669-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 06/12/2019] [Indexed: 11/17/2022] Open
Abstract
Nervous necrosis virus (NNV), Genus Betanodavirus, is the causative agent of viral encephalopathy and retinopathy (VER), a neuropathological disease that causes fish mortalities worldwide. The NNV genome is composed of two single-stranded RNA molecules, RNA1 and RNA2, encoding the RNA polymerase and the coat protein, respectively. Betanodaviruses are classified into four genotypes: red-spotted grouper nervous necrosis virus (RGNNV), striped jack nervous necrosis virus (SJNNV), barfin flounder nervous necrosis virus (BFNNV) and tiger puffer nervous necrosis virus (TPNNV). In Southern Europe the presence of RGNNV, SJNNV and their natural reassortants (in both RNA1/RNA2 forms: RGNNV/SJNNV and SJNNV/RGNNV) has been reported. Pathology caused by these genotypes is closely linked to water temperature and the RNA1 segment encoding amino acids 1–445 has been postulated to regulate viral adaptation to temperature. Reassortants isolated from sole (RGNNV/SJNNV) show 6 substitutions in this region when compared with the RGNNV genotype (positions 41, 48, 218, 223, 238 and 289). We have demonstrated that change of these positions to those present in the RGNNV genotype cause low and delayed replication in vitro when compared with that of the wild type strain at 25 and 30 °C. The experimental infections confirmed the impact of the mutations on viral replication because at 25 °C the viral load and the mortality were significantly lower in fish infected with the mutant than in those challenged with the non-mutated virus. It was not possible to challenge fish at 30 °C because of the scarce tolerance of sole to this temperature.
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Affiliation(s)
- Sandra Souto
- Instituto de Acuicultura, Departamento de Microbiología y Parasitología-Universidade de Santiago de Compostela, 15706, Santiago de Compostela, Spain. .,Unité de Virologie et d'Immunologie Moléculaires, INRA, Université Paris-Saclay, 78350, Jouy-en-Josas, France.
| | - Lucía Vázquez-Salgado
- Instituto de Acuicultura, Departamento de Microbiología y Parasitología-Universidade de Santiago de Compostela, 15706, Santiago de Compostela, Spain
| | - José G Olveira
- Instituto de Acuicultura, Departamento de Microbiología y Parasitología-Universidade de Santiago de Compostela, 15706, Santiago de Compostela, Spain
| | - Isabel Bandín
- Instituto de Acuicultura, Departamento de Microbiología y Parasitología-Universidade de Santiago de Compostela, 15706, Santiago de Compostela, Spain
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8
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Investigation of nervous necrosis virus (NNV) replication in vitro using RNA in situ hybridization. Virus Res 2018; 260:78-85. [PMID: 30472093 DOI: 10.1016/j.virusres.2018.11.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Revised: 11/15/2018] [Accepted: 11/21/2018] [Indexed: 12/16/2022]
Abstract
Nervous necrosis virus (NNV) belongs to the genus Betanodavirus of family Nodaviridae. Its genome consists of two RNA segments, RNA1 and RNA2. Several studies have investigated NNV detection by in situ hybridization (ISH), but these have typically focused on the detection of the RNA2 gene. In this study, we localized both RNA1 and RNA2 NNV segments in viral-infected cells by ISH, using labeled RNA probes (RNA-ISH). Also, immunocytochemistry (ICC) assay was carried out for localization of viral particle by targeting the coat protein. Further, viral quantification assays were performed by quantitative RT-PCR and viral infectivity (TCID50) in SSN-1 cells. Viral segments were observed by RNA-ISH at 6 h post infection (hpi), while NNV particles were detected at 24 hpi by ICC. Use of double labeling RNA-ISH revealed the co-expression of the two viral segments in the same area of the cells, while RNA1 was also detected separately. Comparison of the level of viral genomic segments and viral infectivity revealed significantly more copies of RNA1 at each time points than copies of RNA2 and greater NNV titers. The results suggest that RNA1 might be expressed in the early stages of replication, with RNA2 expressed later. The virions then assemble through initially expressed viral genomic segments. Even though infectious particles displayed very efficient packaging, the RNA1 segment was still over-produced.
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Huang R, Zhou Q, Shi Y, Zhang J, He J, Xie J. Protein A from orange-spotted grouper nervous necrosis virus triggers type I interferon production in fish cell. FISH & SHELLFISH IMMUNOLOGY 2018; 79:234-243. [PMID: 29733958 DOI: 10.1016/j.fsi.2018.05.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Revised: 04/29/2018] [Accepted: 05/02/2018] [Indexed: 06/08/2023]
Abstract
Family Nodaviridae consists of two genera: Alphanodavirus and Betanodavirus, and the latter is classified into four genotypes, including red-spotted grouper nervous necrosis virus, tiger puffer nervous necrosis virus, striped jack nervous necrosis virus, and barfin flounder nervous necrosis virus. Type I interferons (IFNs) play a central role in the innate immune system and antiviral responses, and the interactions between IFN and NNV have been investigated in this study. We have found that the RNA-dependent RNA polymerase (RdRp) from orange-spotted nervous necrosis virus (OGNNV), named protein A, was capable of activating IFN promoter in fathead minnow (FHM) cells. Transient expression of protein A was found to induce IFN expression and secretion, endowing FHM cells with anti-tiger frog virus ability. Protein A from SJNNV can also induce IFN expression in FHM cells but that from Flock House virus (FHV), a well-studied representative species of genus Alphanodavirus, cannot. RdRp activity and mitochondrial localization were shown to be required for protein A to induce IFN expression by means of activating IRF3 but not NFκB. Furthermore, DsRNA synthesized in vitro transcription and poly I:C activated IFN promoter activity when transfected into FHM cells, and dsRNA were also detected in NNV-infected cells. We postulated that dsRNA, a PAMP, was produced by protein A, leading to activation of innate immune response. These results suggest that protein As from NNV are the agonists of innate immune response. This is the first work to demonstrate the interaction between NNV protein A and innate immune system, and may help to understand pathogenesis of NNV.
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Affiliation(s)
- Runqing Huang
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Provincial Key Laboratory of Improved Variety Reproduction in Aquatic Economic Animals, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Qiong Zhou
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Provincial Key Laboratory of Improved Variety Reproduction in Aquatic Economic Animals, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Yan Shi
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Provincial Key Laboratory of Improved Variety Reproduction in Aquatic Economic Animals, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Jing Zhang
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Provincial Key Laboratory of Improved Variety Reproduction in Aquatic Economic Animals, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Jianguo He
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Provincial Key Laboratory of Improved Variety Reproduction in Aquatic Economic Animals, School of Life Sciences, Sun Yat-sen University, Guangzhou, China; School of Marine Sciences, Sun Yat-sen University, Guangzhou, China.
| | - Junfeng Xie
- State Key Laboratory of Biocontrol, Institute of Aquatic Economic Animals and Guangdong Provincial Key Laboratory of Improved Variety Reproduction in Aquatic Economic Animals, School of Life Sciences, Sun Yat-sen University, Guangzhou, China.
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10
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Mao MG, Jiang JL, Jiang ZQ, Liu RT, Zhang QY, Gui JF. Molecular characterization of caspase members and expression response to Nervous Necrosis Virus outbreak in Pacific cod. FISH & SHELLFISH IMMUNOLOGY 2018; 74:559-566. [PMID: 29317308 DOI: 10.1016/j.fsi.2018.01.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2017] [Revised: 01/01/2018] [Accepted: 01/05/2018] [Indexed: 06/07/2023]
Abstract
Multiple functions of caspases include normal cell turnover, proper development and function of the immune system, hormone-dependent atrophy, embryonic development and chemical-induced cell injury. During artificial propagation of Pacific cod, Gadus macrocephalus, high mortality occurred during early development stages. Here, we performed various analyses on the cDNA and protein sequences of six different G. macrocephalus caspases namely GmCasp3, 6, 7, 8, 9 and 10, and tried to investigate the contributions of caspase family to the development and Nervous Necrosis Virus (NNV) resistance. Sequence analysis of GmCaspase proteins showed that each caspase shared conserved domains like "HG", "QACXG (X for R, G or Q)" and "GSWF" except GmCasp10. Sequence alignment and phylogenetic tree showed that GmCasp8 and GmCasp10 were quite different from those of other fishes. 3-D models indicated that structure of GmCasp3 is very conservative, but GmCasp6, 7, 8, 9 and 10 are less conservative. Tissue distribution analysis showed that six Gmcaspases mRNA transcripts were detected in tissues of intestine, gill, thymus, head-kidney and spleen with different abundance, but Gmcasp7 were not detected in the brain. GmCasp3 transcript was kept at very low level in the early development stages, while the expression levels of GmCasp6, 7, 8, 10 were different at various development stages. GmCasp8 level seemed to be much higher than other caspases in the heads of 65dph and 75dph juveniles. To understand the role of caspases during NNV outbreak, modulation in expression of each Gmcaspases were investigated. The results showed that GmCasp3 transcript level increased significantly when NNV broke out, while GmCasp7, 8, 9 and 10 in cod heads decreased obviously at 69dph and 77dph. The results suggest that caspases in Pacific cod should be diverse in their structure and function, and their unique features and response to NNV outbreak add more evidences for the specificity of immune system in Pacific cod.
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Affiliation(s)
- Ming-Guang Mao
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; Key Laboratory of Mariculture and Stock Enhancement in North China's Sea, Ministry of Agriculture, Dalian Ocean University, Dalian 262306, China
| | - Jie-Lan Jiang
- Key Laboratory of Mariculture and Stock Enhancement in North China's Sea, Ministry of Agriculture, Dalian Ocean University, Dalian 262306, China
| | - Zhi-Qiang Jiang
- Key Laboratory of Mariculture and Stock Enhancement in North China's Sea, Ministry of Agriculture, Dalian Ocean University, Dalian 262306, China
| | - Rui-Ting Liu
- Key Laboratory of Mariculture and Stock Enhancement in North China's Sea, Ministry of Agriculture, Dalian Ocean University, Dalian 262306, China
| | - Qi-Ya Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; Key Laboratory of Mariculture and Stock Enhancement in North China's Sea, Ministry of Agriculture, Dalian Ocean University, Dalian 262306, China
| | - Jian-Fang Gui
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; Key Laboratory of Mariculture and Stock Enhancement in North China's Sea, Ministry of Agriculture, Dalian Ocean University, Dalian 262306, China.
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11
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Low CF, Syarul Nataqain B, Chee HY, Rozaini MZH, Najiah M. Betanodavirus: Dissection of the viral life cycle. JOURNAL OF FISH DISEASES 2017; 40:1489-1496. [PMID: 28449248 DOI: 10.1111/jfd.12638] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Revised: 03/02/2017] [Accepted: 03/03/2017] [Indexed: 05/27/2023]
Abstract
Progressive research has been recently made in dissecting the molecular biology of Betanodavirus life cycle, the causative pathogen of viral encephalopathy and retinopathy in economic important marine fish species. Establishment of betanodavirus infectious clone allows the manipulation of virus genome for functional genomic study, which elucidates the biological event of the viral life cycle at molecular level. The betanodavirus strategizes its replication by expressing anti-apoptosis/antinecrotic proteins to maintain the cell viability during early infection. Subsequently utilizes and controls the biological machinery of the infected cells for viral genome replication. Towards the late phase of infection, mass production of capsid protein for virion assembly induces the activation of host apoptosis pathway. It eventually leads to the cell lysis and death, which the lysis of cell contributes to the accomplishment of viral shedding that completes a viral life cycle. The recent efforts to dissect the entire betanodavirus life cycle are currently reviewed.
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Affiliation(s)
- C-F Low
- Institute of Systems Biology, Universiti Kebangsaan Malaysia, Bangi, Selangor, Malaysia
| | - B Syarul Nataqain
- Institute of Systems Biology, Universiti Kebangsaan Malaysia, Bangi, Selangor, Malaysia
| | - H-Y Chee
- Faculty of Medicine and Health Sciences, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
| | - M Z H Rozaini
- Institute of Marine Biotechnology, Universiti Malaysia Terengganu, Kuala Terengganu, Terengganu, Malaysia
| | - M Najiah
- School of Fisheries and Aquaculture Sciences, Universiti Malaysia Terengganu, Kuala Terengganu, Terengganu, Malaysia
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12
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Wen CM. Characterization and viral susceptibility of a brain cell line from brown-marbled grouper Epinephelus fuscoguttatus (Forsskål) with persistent betanodavirus infection. JOURNAL OF FISH DISEASES 2016; 39:1335-1346. [PMID: 27087415 DOI: 10.1111/jfd.12464] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 01/08/2016] [Accepted: 01/10/2016] [Indexed: 06/05/2023]
Abstract
A continuous cell line designated BMGB (brown-marbled grouper brain) was established from the brain tissues of the brown-marbled grouper Epinephelus fuscoguttatus and characterized. BMGB cells were identified as astroglial progenitor cells because they expressed glial fibrillary acidic protein and keratin and were persistently infected by betanodavirus, as confirmed through immunocytochemistry, polymerase chain reaction and immunoblot analyses. Because few intact virions were present in the BMGB cell culture fluid, the cytopathic effect (CPE) was not observed when the culture fluid was inoculated with GBC1 cells. However, BMGB cells displayed typical CPE after infection with additional betanodavirus, megalocytivirus and chum salmon reovirus. BMGB cells showed low myxovirus resistance (Mx) protein expression, which increased following betanodavirus and reovirus infection. Because the cells contained several unusual or degraded viral proteins, the persistent infection of betanodavirus in the BMGB cells may have resulted from a mechanism that destroys the viral proteins rather than the result of Mx protein expression. Despite the persistent betanodavirus infection, BMGB cells proliferated in a manner similar to other normal tropic fish cells and supported the propagation of several piscine viruses; however, the yield was lower than that of normal cells. The BMGB cells will be useful for investigating virus and host cell interaction.
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Affiliation(s)
- C M Wen
- Department of Life Sciences, National University of Kaohsiung, Kaohsiung, Taiwan.
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13
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Wu YC, Tsai PY, Chan JC, Chi SC. Endogenous grouper and barramundi Mx proteins facilitated the clearance of betanodavirus RNA-dependent RNA polymerase. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2016; 59:110-120. [PMID: 26820443 DOI: 10.1016/j.dci.2016.01.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Revised: 01/22/2016] [Accepted: 01/22/2016] [Indexed: 06/05/2023]
Abstract
This study confirmed that the infection of nervous necrosis virus (NNV), belonging to the betanodavirus, can induce the expression of endogenous Mx in grouper fin-3 (GF-3), grouper brain (cGB), and barramundi brain (cBB) cells, but not in grouper fin-1 (GF-1) cells. In a co-sedimentation assay, RdRp appeared in the mitochondrial pellet of GF-1 cells without endogenous Mx expression. However, in GF-3, cGB, and cBB cells, RdRp was detected in the nuclear pellet accompanied by endogenous Mx. By immunostaining, RdRp was found to colocalize with not only endogenous Mx but also lysosomes and monodansylcadaverine (MDC)-labeled autophagic vacuoles. In GF-1 cells, the RdRp level continuously increased during 24-72 h post infection (hpi). When endogenous Mx expressed during 24-72 hpi in virus-infected GF-3, cGB, and cBB cells, the RdRp level peaked at 24 hpi but decreased at 48-72 hpi. The degradation of RdRp could be suppressed by treatment with 3-methyladenine (3MA), NH4Cl, and Mx-specific siRNA respectively. After poly I:C transfection, the endogenous Mx level peaked at 3 days post transfection (dpt) and then spontaneously decreased at 5-7 dpt. The poly I:C-indued Mx also colocalized with MDC-labeled autophagic vacuoles at 3 dpt, and its degradation could be inhibited by 3MA or NH4Cl treatments. Therefore, the anti-NNV mechanism of endogenous grouper and barramundi Mx is suggested to sequester RdRp for degradation through autophagy and lysosomes.
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Affiliation(s)
- Y-C Wu
- Department of Life Science, National Taiwan University, Taipei, Taiwan; Institute of Molecular Medicine, National Taiwan University, Taipei, Taiwan
| | - P-Y Tsai
- Department of Life Science, National Taiwan University, Taipei, Taiwan
| | - J-C Chan
- Department of Life Science, National Taiwan University, Taipei, Taiwan
| | - S-C Chi
- Department of Life Science, National Taiwan University, Taipei, Taiwan.
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14
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Mekata T, Satoh J, Inada M, Dinesh S, Harsha P, Itami T, Sudhakaran R. Development of simple, rapid and sensitive detection assay for grouper nervous necrosis virus using real-time loop-mediated isothermal amplification. JOURNAL OF FISH DISEASES 2015; 38:873-879. [PMID: 25073724 DOI: 10.1111/jfd.12297] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 04/08/2014] [Accepted: 04/08/2014] [Indexed: 06/03/2023]
Abstract
A quantitative rapid detection method based on loop-mediated isothermal amplification has been developed for red-spotted grouper nervous necrosis virus (RGNNV). The nested polymerase chain reaction (PCR) assay is the mainstream inspection of the brooder in the hatchery. In this study, a real-time loop-mediated isothermal amplification (LAMP) method has been applied for RGNNV detection, known as a high-speed gene amplification procedure. Of the three temperatures (60 °C, 63 °C and 65 °C) attempted, it has been found that 63 °C is giving higher amplification from 11th minute onwards. Sensitivity analysis performed in comparison with real-time polymerase chain reaction, reverse transcriptase PCR and nested RT-PCR using various concentrations of template revealed that real-time LAMP method is efficient in terms of cost and time consumption. Specificity analysis revealed that the method developed is specific to RGNNV, whereas it has sequence cross-match with tiger puffer NNV giving advantage in detecting both the viruses. This method could be much efficient in analysing RGNNV in combination with TPNNV.
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Affiliation(s)
- T Mekata
- Aquatic Animal Health Division, National Research Institute of Aquaculture, Fisheries Research Agency, Saiki, Oita, Japan
| | - J Satoh
- Aquatic Animal Health Division, National Research Institute of Aquaculture, Fisheries Research Agency, Saiki, Oita, Japan
| | - M Inada
- Faculty of Agriculture, University of Miyazaki, Miyazaki, Japan
| | - S Dinesh
- Aquaculture Biotechnology Laboratory, School of Biosciences and Technology, VIT University, Vellore, Tamilnadu, India
| | - P Harsha
- Aquaculture Biotechnology Laboratory, School of Biosciences and Technology, VIT University, Vellore, Tamilnadu, India
| | - T Itami
- Faculty of Agriculture, University of Miyazaki, Miyazaki, Japan
| | - R Sudhakaran
- Aquaculture Biotechnology Laboratory, School of Biosciences and Technology, VIT University, Vellore, Tamilnadu, India
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15
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Ahola T, Karlin DG. Sequence analysis reveals a conserved extension in the capping enzyme of the alphavirus supergroup, and a homologous domain in nodaviruses. Biol Direct 2015; 10:16. [PMID: 25886938 PMCID: PMC4392871 DOI: 10.1186/s13062-015-0050-0] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Accepted: 03/24/2015] [Indexed: 12/16/2022] Open
Abstract
Background Members of the alphavirus supergroup include human pathogens such as chikungunya virus, hepatitis E virus and rubella virus. They encode a capping enzyme with methyltransferase-guanylyltransferase (MTase-GTase) activity, which is an attractive drug target owing to its unique mechanism. However, its experimental study has proven very difficult. Results We examined over 50 genera of viruses by sequence analyses. Earlier studies showed that the MTase-GTase contains a “Core” region conserved in sequence. We show that it is followed by a long extension, which we termed “Iceberg” region, whose secondary structure, but not sequence, is strikingly conserved throughout the alphavirus supergroup. Sequence analyses strongly suggest that the minimal capping domain corresponds to the Core and Iceberg regions combined, which is supported by earlier experimental data. The Iceberg region contains all known membrane association sites that contribute to the assembly of viral replication factories. We predict that it may also contain an overlooked, widely conserved membrane-binding amphipathic helix. Unexpectedly, we detected a sequence homolog of the alphavirus MTase-GTase in taxa related to nodaviruses and to chronic bee paralysis virus. The presence of a capping enzyme in nodaviruses is biologically consistent, since they have capped genomes but replicate in the cytoplasm, where no cellular capping enzyme is present. The putative MTase-GTase domain of nodaviruses also contains membrane-binding sites that may drive the assembly of viral replication factories, revealing an unsuspected parallel with the alphavirus supergroup. Conclusions Our work will guide the functional analysis of the alphaviral MTase-GTase and the production of domains for structure determination. The identification of a homologous domain in a simple model system, nodaviruses, which replicate in numerous eukaryotic cell systems (yeast, flies, worms, mammals, and plants), can further help crack the function and structure of the enzyme. Reviewers This article was reviewed by Valerian Dolja, Eugene Koonin and Sebastian Maurer-Stroh. Electronic supplementary material The online version of this article (doi:10.1186/s13062-015-0050-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Tero Ahola
- Department of Food and Environmental Sciences, University of Helsinki, 00014, Helsinki, Finland.
| | - David G Karlin
- Department of Zoology, University of Oxford, Oxford, OX1 3PS, UK. .,The Division of Structural Biology, Henry Wellcome Building, Roosevelt Drive, Oxford, OX3 7BN, UK.
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16
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Gant VU, Moreno S, Varela-Ramirez A, Johnson KL. Two membrane-associated regions within the Nodamura virus RNA-dependent RNA polymerase are critical for both mitochondrial localization and RNA replication. J Virol 2014; 88:5912-26. [PMID: 24696464 PMCID: PMC4093860 DOI: 10.1128/jvi.03032-13] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 01/16/2014] [Indexed: 12/23/2022] Open
Abstract
UNLABELLED Viruses with positive-strand RNA genomes amplify their genomes in replication complexes associated with cellular membranes. Little is known about the mechanism of replication complex formation in cells infected with Nodamura virus. This virus is unique in its ability to lethally infect both mammals and insects. In mice and in larvae of the greater wax moth (Galleria mellonella), Nodamura virus-infected muscle cells exhibit mitochondrial aggregation and membrane rearrangement, leading to disorganization of the muscle fibrils on the tissue level and ultimately in hind limb/segment paralysis. However, the molecular basis for this pathogenesis and the role of mitochondria in Nodamura virus infection remains unclear. Here, we tested the hypothesis that Nodamura virus establishes RNA replication complexes that associate with mitochondria in mammalian cells. Our results showed that Nodamura virus replication complexes are targeted to mitochondria, as evidenced in biochemical, molecular, and confocal microscopy studies. More specifically, we show that the Nodamura virus RNA-dependent RNA polymerase interacts with the outer mitochondrial membranes as an integral membrane protein and ultimately becomes associated with functional replication complexes. These studies will help us to understand the mechanism of replication complex formation and the pathogenesis of Nodamura virus for mammals. IMPORTANCE This study will further our understanding of Nodamura virus (NoV) genome replication and its pathogenesis for mice. NoV is unique among the Nodaviridae in its ability to infect mammals. Here we show that NoV establishes RNA replication complexes (RCs) in association with mitochondria in mammalian cells. These RCs contain newly synthesized viral RNA and feature a physical interaction between mitochondrial membranes and the viral RNA-dependent RNA polymerase (RdRp), which is mediated by two membrane-associated regions. While the nature of the interaction needs to be explored further, it appears to occur by a mode distinct from that described for the insect nodavirus Flock House virus (FHV). The interaction of the NoV RdRp with mitochondrial membranes is essential for clustering of mitochondria into networks that resemble those described for infected mouse muscle and that are associated with fatal hind limb paralysis. This work therefore provides the first link between NoV RNA replication complex formation and the pathogenesis of this virus for mice.
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Affiliation(s)
- Vincent U Gant
- Border Biomedical Research Center and Department of Biological Sciences, The University of Texas at El Paso, El Paso, Texas, USA
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17
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Panzarin V, Cappellozza E, Mancin M, Milani A, Toffan A, Terregino C, Cattoli G. In vitro study of the replication capacity of the RGNNV and the SJNNV betanodavirus genotypes and their natural reassortants in response to temperature. Vet Res 2014; 45:56. [PMID: 24885997 PMCID: PMC4050099 DOI: 10.1186/1297-9716-45-56] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Accepted: 04/24/2014] [Indexed: 11/10/2022] Open
Abstract
Betanodaviruses are the causative agents of viral nervous necrosis and affect a broad range of fish species worldwide. Their bi-segmented genome is composed of the RNA1 and the RNA2 molecules encoding the viral polymerase and the coat protein, respectively. In southern Europe the presence of the RGNNV and the SJNNV genotypes, and the RGNNV/SJNNV and RGNNV/SJNNV reassortants has been documented. Several studies have reported a correlation between water temperature and disease onset. To explore the replication efficiency of betanodaviruses with different genomes in relation to temperature and to understand the role of genetic reassortment on viral phenotype, RGNNV, SJNNV, RGNNV/SJNNV and RGNNV/SJNNV field isolates were fully sequenced, and growth curves generated in vitro at four different temperatures (15, 20, 25, 30 °C) were developed for each isolate. The data obtained, corroborated by statistical analysis, demonstrated that viral titres of diverse betanodavirus genotypes varied significantly in relation to the incubation temperature of the culture. In particular, at 30 °C betanodaviruses under investigation presented different phenotypes, and viruses containing the RNA1 of the RGNNV genotype showed the best replication efficiency. Laboratory results demonstrated that viruses clustering within the same genotype based on the polymerase gene, possess similar growth kinetics in response to temperature, thus highlighting the key role of RNA1 in controlling viral replication at different environmental conditions. The results generated might have practical implications for the inference of viral phenotype according to genetic features and may contribute to a better understanding of betanodavirus ecology.
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Affiliation(s)
- Valentina Panzarin
- Istituto Zooprofilattico Sperimentale delle Venezie, OIE Reference Laboratory for Viral Encephalopathy and Retinopathy, Viale dell'Università 10, 35020 Legnaro, PD, Italy.
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18
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Qiu Y, Wang Z, Liu Y, Qi N, Miao M, Si J, Xiang X, Cai D, Hu Y, Zhou X. Membrane association of Wuhan nodavirus protein A is required for its ability to accumulate genomic RNA1 template. Virology 2013; 439:140-51. [PMID: 23490047 DOI: 10.1016/j.virol.2013.02.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Revised: 01/16/2013] [Accepted: 02/13/2013] [Indexed: 01/13/2023]
Abstract
One common feature of positive-strand RNA viruses is the association of viral RNA and viral RNA replicase proteins with specific intracellular membranes to form RNA replication complexes. Wuhan nodavirus (WhNV) encodes protein A, which is the sole viral RNA replicase. Here, we showed that WhNV protein A closely associates with mitochondrial outer membranes and colocalizes with viral RNA replication sites. We further identified the transmembrane domains (N-terminal aa 33-64 and aa 212-254) of protein A for membrane association and mitochondrial localization. Moreover, we found that protein A accumulates genomic RNA by stabilizing the RNA. And our further investigation revealed that the ability of WhNV protein A to associate with membranes is closely linked with its ability for membrane recruitment and stabilization of viral genomic RNA templates. This study represents an advance toward understanding the mechanism of the RNA replication of WhNV and probably other nodaviruses.
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Affiliation(s)
- Yang Qiu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan, Hubei 430072, China
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Bai H, Wang Y, Li X, Mao H, Li Y, Han S, Shi Z, Chen X. Isolation and characterization of a novel alphanodavirus. Virol J 2011; 8:311. [PMID: 21682922 PMCID: PMC3141682 DOI: 10.1186/1743-422x-8-311] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Accepted: 06/19/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Nodaviridae is a family of non-enveloped isometric viruses with bipartite positive-sense RNA genomes. The Nodaviridae family consists of two genera: alpha- and beta-nodavirus. Alphanodaviruses usually infect insect cells. Some commercially available insect cell lines have been latently infected by Alphanodaviruses. RESULTS A non-enveloped small virus of approximately 30 nm in diameter was discovered co-existing with a recombinant Helicoverpa armigera single nucleopolyhedrovirus (HearNPV) in Hz-AM1 cells. Genome sequencing and phylogenetic assays indicate that this novel virus belongs to the genus of alphanodavirus in the family Nodaviridae and was designated HzNV. HzNV possesses a RNA genome that contains two segments. RNA1 is 3038 nt long and encodes a 110 kDa viral protein termed protein A. The 1404 nt long RNA2 encodes a 44 kDa protein, which exhibits a high homology with coat protein precursors of other alphanodaviruses. HzNV virions were located in the cytoplasm, in association with cytoplasmic membrane structures. The host susceptibility test demonstrated that HzNV was able to infect various cell lines ranging from insect cells to mammalian cells. However, only Hz-AM1 appeared to be fully permissive for HzNV, as the mature viral coat protein essential for HzNV particle formation was limited to Hz-AM1 cells. CONCLUSION A novel alphanodavirus, which is 30 nm in diameter and with a limited host range, was discovered in Hz-AM1 cells.
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Affiliation(s)
- Huimin Bai
- State Key Lab of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan 430071, China
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20
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Identification of RNA regions that determine temperature sensitivities in betanodaviruses. Arch Virol 2010; 155:1597-606. [PMID: 20582605 DOI: 10.1007/s00705-010-0736-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2010] [Accepted: 06/17/2010] [Indexed: 10/19/2022]
Abstract
Betanodaviruses, the causative agents of viral nervous necrosis in marine fish, have bipartite positive-sense RNA genomes. The larger genomic segment, RNA1 (~3.1 kb), encodes an RNA-dependent RNA polymerase (protein A), and the smaller genomic segment RNA2 (~1.4 kb) codes for the coat protein. These viruses can be classified into four genotypes, designated striped jack nervous necrosis virus (SJNNV), redspotted grouper nervous necrosis virus (RGNNV), tiger puffer nervous necrosis virus (TPNNV), and barfin flounder nervous necrosis virus (BFNNV), based on similarities in their partial RNA2 sequences. The optimal temperatures for the growth of these viruses are 20-25°C (SJNNV), 25-30°C (RGNNV), 20°C (TPNNV), and 15-20°C (BFNNV). However, little is known about the mechanisms underlying the temperature sensitivity of these viruses. We first constructed two reassortants between SJNNV and RGNNV to test their temperature sensitivity. The levels of viral growth and RNA replication of these reassortants and parental viruses in cultured fish cells were similar at 25°C. However, the levels of all of the viruses but RGNNV were markedly reduced at 30°C. These results indicate that both RNA1 and RNA2 control the temperature sensitivity of betanodaviruses by modulating RNA replication or earlier viral growth processes. We then constructed ten mutated RGNNVs, the RNA1 segments of which were chimeric between SJNNV and RGNNV, and showed that only chimeric viruses bearing the RGNNV RNA1 region, encoding amino acid residues 1-445, grew similarly to the parental RGNNV at 30°C. This portion of protein A is known to serve as a mitochondrial-targeting signal rather than functioning as an enzymatic domain.
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Wang YD, Kung CW, Chen JY. Antiviral activity by fish antimicrobial peptides of epinecidin-1 and hepcidin 1-5 against nervous necrosis virus in medaka. Peptides 2010; 31:1026-33. [PMID: 20214942 DOI: 10.1016/j.peptides.2010.02.025] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2010] [Revised: 02/24/2010] [Accepted: 02/25/2010] [Indexed: 12/31/2022]
Abstract
The nervous necrosis virus (NNV)-medaka infection model was used in this study for analysis of NNV infection and treatment of NNV with the antimicrobial peptides (AMPs) of epinecidin-1 and hepcidin 1-5 at the organismal level. Our results showed that co-treatment of AMPs with the virus was effective in promoting a significant increase in medaka survival. Re-challenge with the virus also showed high survival suggesting that these two AMPs enhanced fish survival. However, pretreatment or post-treatment with AMPs showed that both of these AMPs increased medaka survival and suggested that AMPs can be used as drugs to rescue infected medaka. The data presented here indicate that epinecidin-1 and hepcidin 1-5 have in vivo antivirus activity against the NNV, and hepcidin 1-5 functions like a lytic peptide after an in vitro assay. Infection after pretreatment, co-treatment, and post-treatment with epinecidin-1 or hepcidin 1-5 was verified by RT-PCR which showed both peptides can downregulate NNV and interferon gene expressions. In addition, our results suggest that epinecidin-1 or hepcidin 1-5 may prove to be an effective chemotherapeutic agent for aquaculture in the future.
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Affiliation(s)
- Yi-Da Wang
- Marine Research Station, Institute of Cellular and Organismic Biology, Academia Sinica, 23-10 Dahuen Rd., Jiaushi, Ilan 262, Taiwan
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22
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Mochizuki T, Hirai K, Kanda A, Ohnishi J, Ohki T, Tsuda S. Induction of necrosis via mitochondrial targeting of Melon necrotic spot virus replication protein p29 by its second transmembrane domain. Virology 2009; 390:239-49. [PMID: 19501870 DOI: 10.1016/j.virol.2009.05.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2009] [Revised: 03/21/2009] [Accepted: 05/10/2009] [Indexed: 01/10/2023]
Abstract
The virulence factor of Melon necrotic spot virus (MNSV), a virus that induces systemic necrotic spot disease on melon plants, was investigated. When the replication protein p29 was expressed in N. benthamiana using a Cucumber mosaic virus vector, necrotic spots appeared on the leaf tissue. Transmission electron microscopy revealed abnormal mitochondrial aggregation in these tissues. Fractionation of tissues expressing p29 and confocal imaging using GFP-tagged p29 revealed that p29 associated with the mitochondrial membrane as an integral membrane protein. Expression analysis of p29 deletion fragments and prediction of hydrophobic transmembrane domains (TMDs) in p29 showed that deletion of the second putative TMD from p29 led to deficiencies in both the mitochondrial localization and virulence of p29. Taken together, these results indicated that MNSV p29 interacts with the mitochondrial membrane and that p29 may be a virulence factor causing the observed necrosis.
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23
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Hwang YT, McCartney AW, Gidda SK, Mullen RT. Localization of the Carnation Italian ringspot virus replication protein p36 to the mitochondrial outer membrane is mediated by an internal targeting signal and the TOM complex. BMC Cell Biol 2008; 9:54. [PMID: 18811953 PMCID: PMC2573885 DOI: 10.1186/1471-2121-9-54] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2008] [Accepted: 09/23/2008] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Carnation Italian ringspot virus (CIRV) is a positive-strand RNA virus that causes massive structural alterations of mitochondria in infected host cells, the most conspicuous being the formation of numerous internal vesicles/spherules that are derived from the mitochondrial outer membrane and serve as the sites for viral RNA replication. While the membrane-bound components of the CIRV replication complex, including a 36-kD RNA-binding protein (p36), are known to be essential for these changes in mitochondrial morphology and are relatively well characterized in terms of their roles in nascent viral RNA synthesis, how these proteins are specifically targeted and inserted into mitochondria is poorly defined. RESULTS Here we report on the molecular signal responsible for sorting p36 to the mitochondrial outer membrane. Using a combination of gain-of-function assays with portions of p36 fused to reporter proteins and domain-swapping assays with p36 and another closely-related viral RNA-binding protein, p33, that sorts specifically to the peroxisomal boundary membrane, we show that the mitochondrial targeting information in p36 resides within its two transmembrane domains (TMDs) and intervening hydrophilic loop sequence. Comprehensive mutational analysis of these regions in p36 revealed that the primary targeting determinants are the moderate hydrophobicity of both TMDs and the positively-charged face of an amphipathic helix within the intervening loop sequence. We show also using bimolecular fluorescence complementation (BiFC) that p36 interacts with certain components of the translocase complex in the mitochondrial outer membrane (TOM), but not with the sorting and assembly machinery (SAM). CONCLUSION Our results provide insight to how viruses, such as CIRV, exploit specific host-cell protein sorting pathways to facilitate their replication. The characterization of the targeting and insertion of p36 into the mitochondrial outer membrane also sheds light on the mechanisms involved in sorting of host-cell membrane proteins to mitochondria, a process that has been largely unexplored in plants.
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Affiliation(s)
- Yeen Ting Hwang
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
| | - Andrew W McCartney
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
- JD Irving, Limited, Woodlands Division, 1350 Regent Street, Fredericton, New Brunswick, E3C 2G6, Canada
| | - Satinder K Gidda
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
| | - Robert T Mullen
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
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Adachi K, Ichinose T, Watanabe K, Kitazato K, Kobayashi N. Potential for the replication of the betanodavirus redspotted grouper nervous necrosis virus in human cell lines. Arch Virol 2007; 153:15-24. [PMID: 17906832 PMCID: PMC7086817 DOI: 10.1007/s00705-007-1051-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2007] [Accepted: 07/24/2007] [Indexed: 11/25/2022]
Abstract
The determination of the host ranges of viruses is important because of the possible emergence of infectious agents, which may result from the zoonotic transmission of animal viruses to humans. The family Nodaviridae, whose members are non-enveloped, positive-stranded bipartite RNA viruses, is comprised of the genera Alphanodavirus and Betanodavirus, whose members predominantly infect insects and fish, respectively. The alphanodaviruses can also infect suckling mice and suckling hamsters, resulting in paralysis and death. Pigs near the site of isolation of the Nodamura virus (NoV), an alphanodavirus, have been reported to have high levels of NoV neutralizing antibody, suggesting that they may be part of the natural host range of this virus. Betanodaviruses are the causative agents of viral nervous necrosis, which occurs in several species of fish. However, little is known regarding the mechanism of infection of these viruses. Whether betanodaviruses can infect hosts other than fish remains unclear. In this study, we examined the possibility that a betanodavirus, redspotted grouper nervous necrosis virus (RGNNV), can infect human cell lines and showed that this virus can attach to the cells but cannot penetrate them, although human cells can support the replication of the betanodavirus when viral RNAs are transfected. The betanodavirus in its present form cannot infect human cells.
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Affiliation(s)
- K. Adachi
- />Laboratory of Molecular Biology of Infectious Agents, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - T. Ichinose
- />Laboratory of Molecular Biology of Infectious Agents, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - K. Watanabe
- />Laboratory of Molecular Biology of Infectious Agents, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - K. Kitazato
- />Laboratory of Molecular Biology of Infectious Agents, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - N. Kobayashi
- />Laboratory of Molecular Biology of Infectious Agents, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
- />Central Research Center, AVSS Corporation, Nagasaki, Japan
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Adachi K, Ichinose T, Takizawa N, Watanabe K, Kitazato K, Kobayashi N. Inhibition of betanodavirus infection by inhibitors of endosomal acidification. Arch Virol 2007; 152:2217-24. [PMID: 17891330 PMCID: PMC7086734 DOI: 10.1007/s00705-007-1061-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2007] [Accepted: 08/27/2007] [Indexed: 12/03/2022]
Abstract
Betanodaviruses, members of the family Nodaviridae, have small positive-stranded bipartite RNA genomes and are the causal agent of viral nervous necrosis (VNN) in many species of marine farmed fish. In the aquaculture industry, outbreaks of betanodavirus infection and spread in larval and juvenile fish result in devastating damage and heavy economic loss. Although an urgent need exists to develop drugs that inhibit betanodavirus infection, there have been no reports about anti-betanodavirus drugs. Recently, it was reported that betanodaviruses were detected in the endosomes of infected cells, suggesting that betanodaviruses enter fish cells by endocytosis. This finding prompted us to examine whether blocking this endosomal pathway could provide a target for antiviral drug development. In this study, we examined the inhibitory effect of several lysosomotropic agents against betanodavirus infection in fish E-11 cells. The presence of 1 mM NH4Cl or 1 µM chloroquine in the medium inhibited the entry of betanodaviruses into cells and inhibited viral infection. The lysosomotropic agents bafilomycin A1 and monensin also inhibited virus-induced cytopathology and virus production. Our data demonstrate that inhibitors of endosomal acidification are candidates as antiviral agents against betanodavirus.
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Affiliation(s)
- K Adachi
- Laboratory of Molecular Biology of Infectious Agents, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
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26
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Mézeth KB, Nylund S, Henriksen H, Patel S, Nerland AH, Szilvay AM. RNA-dependent RNA polymerase from Atlantic halibut nodavirus contains two signals for localization to the mitochondria. Virus Res 2007; 130:43-52. [PMID: 17602779 DOI: 10.1016/j.virusres.2007.05.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2006] [Revised: 05/08/2007] [Accepted: 05/14/2007] [Indexed: 11/21/2022]
Abstract
Nodaviruses encode an RNA-dependent RNA polymerase called Protein A that is responsible for replication of the viral RNA segments. The intracellular localization of Protein A from a betanodavirus isolated from Atlantic halibut (AHNV) was studied in infected fish cells and in transfected mammalian cells expressing Myc-tagged wild type Protein A and mutants. In infected cells Protein A localized to cytoplasmic structures resembling mitochondria and in transfected mammalian cells the AHNV Protein A was found to co-localize with mitochondrial proteins. Two independent mitochondrial targeting signals, one N-terminal comprising residues 1-40 and one internal consisting of residues 225-246 were sufficient to target both Protein A deletion mutants and enhanced green fluorescent protein (EGFP) to the mitochondria. The N-terminal signal corresponds to the mitochondrial targeting sequence of the Flock House Virus (FHV) Protein A while the internal signal is similar to the single targeting signal previously found in Greasy Grouper Nervous Necrosis Virus (GGNNV) Protein A.
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Fenner BJ, Thiagarajan R, Chua HK, Kwang J. Betanodavirus B2 is an RNA interference antagonist that facilitates intracellular viral RNA accumulation. J Virol 2007; 80:85-94. [PMID: 16352533 PMCID: PMC1317529 DOI: 10.1128/jvi.80.1.85-94.2006] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Betanodaviruses are small positive-sense bipartite RNA viruses that infect a wide variety of fish species and are notorious for causing lethal outbreaks in juvenile fish hatcheries worldwide. The function of a small nonstructural protein, B2, encoded by the subgenomic RNA3 of betanodaviruses, has remained obscure. Greasy grouper nervous necrosis virus, a betanodavirus model, was used to develop a facile DNA-based reverse genetics system that recapitulated the virus infection cycle, and we used this system to show that B2 is a small nonstructural protein that is essential for high level accumulation of viral RNA1 after RNA transfection of fish, mammalian, and avian cells. The defect in RNA1 accumulation in a B2 mutant was partially complemented by supplying B2 RNA in trans. Confocal analysis of the cellular distribution of B2 indicated that B2 is able to enter the nucleus and accumulates there during the late stages of GGNNV infection. Using human HeLa cells as a cellular RNA interference model, we found that B2 could efficiently antagonize RNA interference, which is a property shared by the distantly related alphanodavirus B2 proteins. This function provides appears to provide an explanation, at least in part, for why B2 mutant RNA1 is severely impaired in its intracellular accumulation.
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Affiliation(s)
- Beau J Fenner
- Animal Health Biotechnology, Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore 117604
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28
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Chen W, Zhang J, Dong C, Yang B, Li Y, Liu C, Hu Y. Identification of Transmembrane Domain of a Membrane Associated Protein NS5 of Dendrolimus punctatus Cytoplasmic Polyhedrosis Virus. BMB Rep 2006; 39:412-7. [PMID: 16889685 DOI: 10.5483/bmbrep.2006.39.4.412] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We examined the intracellular localization of NS5 protein of Dendrolimus punctatus cytoplasmic polyhedrosis virus (DpCPV) by expressing NS5-GFP fusion protein and proteins from deletion mutants of NS5 in baculovirus recombinant infected insect Spodoptera frugiperda (Sf-9) cells. It was found that the NS5 protein was present at the plasma membrane of the cells, and that the N-terminal portion of the protein played a key role in the localization. A transmembrane region was identified to be present in the N-terminal portion of the protein, and the detailed transmembrane domain (SQIHMVWVKSGLVFF, 57-71aa) of N-terminal portion of NS5 was further determined, which was accorded with the predicted results, these findings suggested that NS5 might have an important function in viral life cycle.
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Affiliation(s)
- Wuguo Chen
- State Key Laboratory of Virology and Department of Biotechnology, College of Life Sciences, Wuhan University, Wuhan, Hubei 430072, P. R. China
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29
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Fenner BJ, Du Q, Goh W, Thiagarajan R, Chua HK, Kwang J. Detection of betanodavirus in juvenile barramundi, Lates calcarifer (Bloch), by antigen capture ELISA. JOURNAL OF FISH DISEASES 2006; 29:423-32. [PMID: 16866926 DOI: 10.1111/j.1365-2761.2006.00736.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Betanodavirus infection of fish has been responsible for mass mortalities in aquaculture hatcheries worldwide. Betanodaviruses possess a bipartite single-stranded RNA genome consisting of the 3.1 kb RNA1 encoding an RNA-dependent RNA polymerase and the B2 protein, while the 1.4 kb RNA2 encodes the viral nucleocapsid protein, alpha. A panel of six monoclonal antibodies against the alpha protein of greasy grouper nervous necrosis virus (GGNNV) was developed for use in diagnostics. All antibodies reacted with native and recombinant alpha in immunoblot and indirect immunofluorescence assays. Each of the monoclonal antibodies reacted against discrete regions of the alpha protein, though none reacted with the extreme C-terminal region of the protein. One of the monoclonal antibodies, specific for the K151-T246 region of alpha, was used for the development of an antigen capture ELISA. In this assay we could detect 10(3)-10(4) TCID(50) units of virus derived from infected tissue culture supernatants. Head tissue extracts prepared from experimentally infected barramundi, Lates calcarifer, juveniles were assayed for GGNNV using the antigen capture assay and a clear increase in alpha antigen was detected from 5 to 15 days post-challenge. The assay thus represents a useful method for field-based detection of betanodavirus in fish hatcheries.
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Affiliation(s)
- B J Fenner
- Animal Health Biotechnology, Temasek Life Sciences Laboratory, National University of Singapore, Singapore
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Fenner BJ, Goh W, Kwang J. Sequestration and protection of double-stranded RNA by the betanodavirus b2 protein. J Virol 2006; 80:6822-33. [PMID: 16809288 PMCID: PMC1489041 DOI: 10.1128/jvi.00079-06] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2006] [Accepted: 04/24/2006] [Indexed: 12/31/2022] Open
Abstract
Betanodavirus B2 belongs to a group of functionally related proteins from the sense-strand RNA virus family Nodaviridae that suppress cellular RNA interference. The B2 proteins of insect alphanodaviruses block RNA interference by binding to double-stranded RNA (dsRNA), thus preventing Dicer-mediated cleavage and the subsequent generation of short interfering RNAs. We show here that the fish betanodavirus B2 protein also binds dsRNA. Binding is sequence independent, and maximal binding occurs with dsRNA substrates greater than 20 bp in length. The binding of B2 to long dsRNA is sufficient to completely block Dicer cleavage of dsRNA in vitro. Protein-protein interaction studies indicated that B2 interacts with itself and with other dsRNA binding proteins, the interaction occurring through binding to shared dsRNA substrates. Induction of the dsRNA-dependent interferon response was not antagonized by B2, as the interferon-responsive Mx gene of permissive fish cells was induced by wild-type viral RNA1 but not by a B2 mutant. The induction of Mx instead relied solely on viral RNA1 accumulation, which is impaired in the B2 mutant. Hyperediting of virus dsRNA and site-specific editing of 5-HT2C mRNA were both antagonized by B2. RNA editing was not, however, observed in transfected wild-type or B2 mutant RNA1, suggesting that this pathway does not contribute to the RNA1 accumulation defect of the B2 mutant. We thus conclude that betanodavirus B2 is a dsRNA binding protein that sequesters and protects both long and short dsRNAs to protect betanodavirus from cellular RNA interference.
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Affiliation(s)
- Beau J Fenner
- Animal Health Biotechnology, Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore 117604
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Sagan SM, Rouleau Y, Leggiadro C, Supekova L, Schultz PG, Su AI, Pezacki JP. The influence of cholesterol and lipid metabolism on host cell structure and hepatitis C virus replication. Biochem Cell Biol 2006; 84:67-79. [PMID: 16462891 DOI: 10.1139/o05-149] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The hepatitis C virus (HCV) replicates on a membrane protein complex composed of viral proteins, replicating RNA, and altered cellular membranes. Small-molecule inhibitors of cellular lipid-cholesterol metabolism such as 25-hydroxycholesterol, cerulenin, lovastatin, and GGTI-286 all show a negative effect on HCV replication. Perturbation of host cell lipid and cholesterol metabolism can disrupt replication complexes by altering membranous structures where replication occurs. Changes in cholesterol and (or) lipid composition can have a general effect on membrane structure. Alternatively, metabolic changes can exert a more subtle influence over replication complexes by altering localization of host proteins through alterations in lipid anchoring. Here, we use Huh-7 cells harboring subgenomic HCV replicons to demonstrate that 25-hydroxycholesterol, cerulenin, lovastatin, and GGTI-286 do not disrupt the membranous web where replication occurs, whereas cholesterol-depleting agents such as beta-cyclodextrin do. Cellular imaging suggests that the HCV RNA can remain associated with subcellular compartments connected with replication complexes in the presence of metabolic inhibitors. Therefore, at least 2 different molecular mechanisms are possible for the inhibition of HCV replication through the modulation of cellular lipid and cholesterol metabolism.
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Affiliation(s)
- Selena M Sagan
- Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, ON
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Chen SP, Yang HL, Her GM, Lin HY, Jeng MF, Wu JL, Hong JR. Betanodavirus induces phosphatidylserine exposure and loss of mitochondrial membrane potential in secondary necrotic cells, both of which are blocked by bongkrekic acid. Virology 2006; 347:379-91. [PMID: 16430940 DOI: 10.1016/j.virol.2005.11.052] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2005] [Revised: 09/27/2005] [Accepted: 11/29/2005] [Indexed: 01/02/2023]
Abstract
In this study, we show how the red spotted grouper nervous necrosis virus (RGNNV) causes loss of mitochondrial membrane potential and promotes host secondary apoptotic necrosis. RGNNV viral proteins such as protein alpha (42 kDa) and protein A (110 kDa) were quickly expressed between 12 h and 24 h postinfection (p.i.) in GL-av cells. Annexin V staining revealed that the NNV infection of GL-av cells induced phosphatidylserine (PS) externalization and development of bulb-like vesicles (bleb formation) at 24 h p.i. NNV infection also induced DNA fragmentation detectable by TUNEL assay between 12 h (8%) and 72 h (32%) p.i. Bongkrekic acid (1.6 microM; BKA) blocked permeability of the mitochondrial permeability transition pore, but cyclosporine A (CsA) did not block secondary necrosis. Finally, secondary necrotic cells were not engulfed by neighboring cells. Our data suggest that RGNNV induces apoptotic death via opening the mitochondrial permeability transition pore thereby triggering secondary necrosis in the mid-apoptotic phase.
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Affiliation(s)
- Shi-Ping Chen
- Laboratory of Molecular Virology and Biotechnology, Institute of Biotechnology, National Cheng-Kung University, Tainan 701, Taiwan, ROC
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Valentin C, Dunoyer P, Vetter G, Schalk C, Dietrich A, Bouzoubaa S. Molecular basis for mitochondrial localization of viral particles during beet necrotic yellow vein virus infection. J Virol 2005; 79:9991-10002. [PMID: 16014959 PMCID: PMC1181617 DOI: 10.1128/jvi.79.15.9991-10002.2005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2004] [Accepted: 04/16/2005] [Indexed: 11/20/2022] Open
Abstract
During infection, Beet necrotic yellow vein virus (BNYVV) particles localize transiently to the cytosolic surfaces of mitochondria. To understand the molecular basis and significance of this localization, we analyzed the targeting and membrane insertion properties of the viral proteins. ORF1 of BNYVV RNA-2 encodes the 21-kDa major coat protein, while ORF2 codes for a 75-kDa minor coat protein (P75) by readthrough of the ORF1 stop codon. Bioinformatic analysis highlighted a putative mitochondrial targeting sequence (MTS) as well as a major (TM1) and two minor (TM3 and TM4) transmembrane regions in the N-terminal part of the P75 readthrough domain. Deletion and gain-of-function analyses based on the localization of green fluorescent protein (GFP) fusions showed that the MTS was able to direct a reporter protein to mitochondria but that the protein was not persistently anchored to the organelles. GFP fused either to MTS and TM1 or to MTS and TM3-TM4 efficiently and specifically associated with mitochondria in vivo. The actual role of the individual domains in the interaction with the mitochondria seemed to be determined by the folding of P75. Anchoring assays to the outer membranes of isolated mitochondria, together with in vivo data, suggest that the TM3-TM4 domain is the membrane anchor in the context of full-length P75. All of the domains involved in mitochondrial targeting and anchoring were also indispensable for encapsidation, suggesting that the assembly of BNYVV particles occurs on mitochondria. Further data show that virions are subsequently released from mitochondria and accumulate in the cytosol.
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Affiliation(s)
- Clarisse Valentin
- Institut de Biologie Moléculaire des Plantes du CNRS, Strasbourg, France
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