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Zhan Z, Chen H, Liao X, Wu S, Lei X, Xu Q, Cao H, Qin Q, Wei J. Singapore grouper iridovirus VP128 inhibits STING-TBK1 mediated signaling to evade antiviral immunity. FISH & SHELLFISH IMMUNOLOGY 2024; 152:109774. [PMID: 39019127 DOI: 10.1016/j.fsi.2024.109774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2024] [Revised: 07/07/2024] [Accepted: 07/15/2024] [Indexed: 07/19/2024]
Abstract
Singapore grouper iridovirus (SGIV) belongs to the family Iridoviridae and the genus Ranavirus, which is a large cytoplasmic DNA virus. Infection of grouper with SGIV can cause hemorrhage and swelling of the spleen of the fish. Previous work on genome annotation demonstrated that SGIV contained numerous uncharacterized or hypothetical open reading frames (ORFs), whose functions remained largely unknown. In the present study, the protein encoded by SGIV ORF128 (VP128) was identified. VP128 is predominantly localized within the endoplasmic reticulum (ER). Overexpression of VP128 significantly promoted SGIV replication. VP128 inhibited the interferon (IFN)-3 promoter activity and mRNA level of IFN-related genes induced by poly(I:C), Epinephelus coioides cyclic GMP/AMP synthase (EccGAS)/stimulator of IFN genes (EcSTING), and TANK-binding kinase 1 (EcTBK1). Moreover, VP128 interacted with EcSTING and EcTBK1. The interaction between VP128 and EcSTING was independent of any specific structural domain of EcSTING. Together, our results demonstrated that SGIV VP128 negatively regulated the IFN response by inhibiting EcSTING-EcTBK1 signaling for viral evasion.
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Affiliation(s)
- Zhouling Zhan
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Hong Chen
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Xinyu Liao
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Siting Wu
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Xiaoxia Lei
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Qiongyue Xu
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Helong Cao
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Qiwei Qin
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China; Nansha-South China Agricultural University Fishery Research Institute, Guangzhou, Guangzhou, 511400, China; Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, 266000, China.
| | - Jingguang Wei
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China; Nansha-South China Agricultural University Fishery Research Institute, Guangzhou, Guangzhou, 511400, China.
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Wang L, Li Q, Wen X, Zhang X, Wang S, Qin Q. Dissecting the early and late endosomal pathways of Singapore grouper iridovirus by single-particle tracking in living cells. Int J Biol Macromol 2024; 256:128336. [PMID: 38013078 DOI: 10.1016/j.ijbiomac.2023.128336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 10/10/2023] [Accepted: 11/12/2023] [Indexed: 11/29/2023]
Abstract
Iridoviruses are large DNA viruses that infect a wide range of invertebrates and lower vertebrates, causing serious threats to ecological security and aquaculture industry worldwide. However, the mechanisms underlying intracellular transport of iridovirus remain unknown. In this study, the transport of Singapore grouper iridovirus (SGIV) in early endosomes (EEs) and late endosomes (LEs) was explored by single-particle tracking technology. SGIV employs EEs to move rapidly from the cell membrane to the nucleus, and this long-range transport is divided into "slow-fast-slow" stages. SGIV within LEs mainly underwent oscillatory movements near the nucleus. Furthermore, SGIV entered newly formed EEs and LEs, respectively, possibly based on the interaction between the viral major capsid protein and Rab5/Rab7. Importantly, interruption of EEs and LEs by the dominant negative mutants of Rab5 and Rab7 significantly inhibited the movement of SGIV, suggesting the important roles of Rab5 and Rab7 in virus transport. In addition, it seems that SGIV needs to enter clathrin-coated vesicles to move from actin to microtubules before EEs carry the virus moving along microtubules. Together, our results for the first time provide a model whereby iridovirus transport depending on EEs and LEs, helping to clarify the mechanism underlying iridovirus infection, and provide a convenient tactic to investigate the dynamic infection of large DNA virus.
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Affiliation(s)
- Liqun Wang
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China; Henry Fok School of Biology and Agriculture, Shaoguan University, Shaoguan 512005, China
| | - Qiang Li
- College of Oceanology and meteorology, Guangdong Ocean University, Zhanjiang 524088, China
| | - Xiaozhi Wen
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China
| | - Xinyue Zhang
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China
| | - Shaowen Wang
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China; Nansha-South China Agricultural University Fishery Research Institute, Guangzhou 511464, China.
| | - Qiwei Qin
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou 510642, China; Nansha-South China Agricultural University Fishery Research Institute, Guangzhou 511464, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266000, China; Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai 519082, China.
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3
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Xu L, Liu M, Chen H, Zhang L, Xu Q, Zhan Z, Xu Z, Liu S, Wu S, Zhang X, Qin Q, Wei J. Singapore grouper iridovirus VP122 targets grouper STING to evade the interferon immune response. FISH & SHELLFISH IMMUNOLOGY 2023; 140:108990. [PMID: 37558148 DOI: 10.1016/j.fsi.2023.108990] [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: 06/05/2023] [Revised: 07/23/2023] [Accepted: 08/07/2023] [Indexed: 08/11/2023]
Abstract
Singapore grouper iridovirus (SGIV) is a highly pathogenic Iridoviridae that causes hemorrhage and spleen enlargement in grouper. Despite previous genome annotation efforts, many open reading frames (ORFs) in SGIV remain uncharacterized, with largely unknown functions. In this study, we identified the protein encoded by SGIV ORF122, now referred to as VP122. Notably, overexpression of VP122 promoted SGIV replication. Moreover, VP122 exhibited antagonistic effects on the natural antiviral immune response through the cGAS-STING signaling pathway. It specifically inhibited the cGAS-STING-triggered transcription of various immune-related genes, including IFN1, IFN2, ISG15, ISG56, PKR, and TNF-α in GS cells. Additionally, VP122 significantly inhibited the activation of the ISRE promoter mediated by EccGAS and EcSTING but had no effect on EccGAS or EcSTING alone. Immunoprecipitation and Western blotting experiments revealed that VP122 specifically interacts with EcSTING but not EccGAS. Notably, this interaction between VP122 and EcSTING was independent of any specific domain of EcSTING. Furthermore, VP122 inhibited the self-interaction of EcSTING. Interestingly, VP122 did not affect the recruitment of EcTBK1 and EcIRF3 to the EcSTING complex. Collectively, our results demonstrate that SGIV VP122 targets EcSTING to evade the type I interferon immune response, revealing a crucial role for VP122 in modulating the host-virus interaction.
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Affiliation(s)
- Linting Xu
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Mengke Liu
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Hong Chen
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Luhao Zhang
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Qiongyue Xu
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Zhouling Zhan
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Zhuqing Xu
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Shaoli Liu
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Siting Wu
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Xin Zhang
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Qiwei Qin
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China; Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, 266000, China; Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, 528478, China.
| | - Jingguang Wei
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China; Department of Biological Sciences, National University of Singapore, 117543, Singapore.
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Singapore Grouper Iridovirus VP131 Drives Degradation of STING-TBK1 Pathway Proteins and Negatively Regulates Antiviral Innate Immunity. J Virol 2022; 96:e0068222. [PMID: 36190239 PMCID: PMC9599571 DOI: 10.1128/jvi.00682-22] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Iridoviruses are large DNA viruses which cause great economic losses to the aquaculture industry and serious threats to ecological diversity worldwide. Singapore grouper iridovirus (SGIV), a novel member of the genus Ranavirus, causes high mortality in grouper aquaculture. Previous work on genome annotation demonstrated that SGIV contained numerous uncharacterized or hypothetical open reading frames (ORFs), whose functions remained largely unknown. Here, we reported that the protein encoded by SGIV ORF131R (VP131) was localized predominantly within the endoplasmic reticulum (ER). Ectopic expression of GFP-VP131 significantly enhanced SGIV replication, while VP131 knockdown decreased viral infection in vitro, suggesting that VP131 functioned as a proviral factor during SGIV infection. Overexpression of GFP-VP131 inhibited the interferon (IFN)-1 promoter activity and mRNA level of IFN-related genes induced by poly(I:C), Epinephelus coioides cyclic GMP/AMP synthase (EccGAS)/stimulator of IFN genes (EcSTING), TANK-binding kinase 1 (EcTBK1), or melanoma differentiation-associated gene 5 (EcMDA5), whereas such activation induced by mitochondrial antiviral signaling protein (EcMAVS) was not affected. Moreover, VP131 interacted with EcSTING and degraded EcSTING through both the autophagy-lysosome pathway and ubiquitin-proteasome pathway, and targeted for the K63-linked ubiquitination. Of note, we also found that EcSTING significantly accelerated the formation of GFP-VP131 aggregates in co-transfected cells. Finally, GFP-VP131 inhibited EcSTING- or EcTBK1-induced antiviral activity upon red-spotted grouper nervous necrosis virus (RGNNV) infection. Together, our results demonstrated that the SGIV VP131 negatively regulated the IFN response by inhibiting EcSTING-EcTBK1 signaling for viral evasion. IMPORTANCE STING has been identified as a critical factor participating in the innate immune response which recruits and phosphorylates TBK1 and IFN regulatory factor 3 (IRF3) to induce IFN production and defend against viral infection. However, viruses also distort the STING-TBK1 pathway to negatively regulate the IFN response and facilitate viral replication. Here, we reported that SGIV VP131 interacted with EcSTING within the ER and degraded EcSTING, leading to the suppression of IFN production and the promotion of SGIV infection. These results for the first time demonstrated that fish iridovirus evaded the host antiviral response via abrogating the STING-TBK1 signaling pathway.
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Wei S, Han H, Xu S, Huang Y, Wei J, Qin Q. Identification and functional characterization of Cystatin B in orange-spotted grouper, Epinephelus coioides. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2022; 132:104383. [PMID: 35300987 DOI: 10.1016/j.dci.2022.104383] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Revised: 02/23/2022] [Accepted: 03/01/2022] [Indexed: 06/14/2023]
Abstract
Cystatin B is a cysteine protease inhibitor that plays a crucial role in immune response. Nevertheless, the molecular mechanism of fish Cystatin B in virus replication remains obscure. In this study, we identified and characterized Cystatin B (Ec-CysB) in the orange-spotted grouper (Epinephelus coioides). The Ec-CysB encoded a 100-amino acid protein with the conserved QXVXG motif, PC motif and cysteine protease inhibitory motif, which shared high identities with reported Cystatin B. The abundant transcriptional level of Ec-CysB was found in gill, intestine and head kidney. And the Ec-CysB expression was significantly up-regulated in spleen after infection with Singapore grouper iridovirus (SGIV) in vitro. Subcellular localization analysis revealed that Ec-CysB was distributed mainly in the cytoplasm and nucleus. Further studies showed that overexpression of Ec-CysB in vitro significantly increased SGIV replication and virus-induced cell apoptosis, but replication of SGIV was inhibited by knockdown or mutant of Ec-CysB. Moreover, overexpression of Ec-CysB significantly inhibited the interferon (IFN), interferon-stimulated response element (ISRE) promoter activities, and enhanced apoptosis-related transcription factors p53 promoter activities. Collectively, our results suggest that Ec-CysB affect viral replication and virus-induced cell apoptosis, which will help us to explore its potential functions during SGIV infection.
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Affiliation(s)
- Shina Wei
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Honglin Han
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Suifeng Xu
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Youhua Huang
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Jingguang Wei
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China
| | - Qiwei Qin
- College of Marine Sciences, South China Agricultural University, Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, 510642, China; Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), 528478, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266000, China.
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Wu G, Lin Q, Lim TK, Zhang Y, Aweya JJ, Zhu J, Yao D. The interactome of Singapore grouper iridovirus protein ICP18 as revealed by proximity-dependent BioID approach. Virus Res 2020; 291:198218. [PMID: 33152380 DOI: 10.1016/j.virusres.2020.198218] [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: 05/11/2020] [Revised: 10/22/2020] [Accepted: 10/26/2020] [Indexed: 12/14/2022]
Abstract
Singapore grouper iridovirus (SGIV) is a large double-stranded DNA virus that is a major threat to grouper aquaculture. The pathogenesis of SGIV is not well understood so far. Previous studies have revealed that ICP18, an immediate early protein encoded by SGIV ORF086R gene, promotes viral replication by regulating cell proliferation and virus assembly. In the present study, the potential functions of ICP18 were further explored by probing into its interactors using a proximity-dependent BioID method. Since our in-house grouper embryonic cells (a natural host cell of SGIV) could not be efficiently transfected with the plasmid DNA, and the grouper genome data for mass spectrometry-based protein identification is not currently available, we chosen a non-permissive cell (HEK293 T) as a substitute for this study. A total of 112 cellular proteins that potentially bind to ICP18 were identified by mass spectrometry analysis. Homology analysis showed that among these identified proteins, 110 candidate ICP18-interactors had homologous proteins in zebrafish (a host of SGIV), and shared high sequence identity. Further analysis revealed that the identified ICP18-interacting proteins modulate various cellular processes such as cell cycle and cell adhesion. In addition, the interaction between ICP18 and its candidate interactor, i.e., cyclin-dependent kinase1 (CDK1), was confirmed using Co-immunoprecipitation (Co-IP) and Pull-down assays. Collectively, our present data provides additional insight into the biological functions of ICP18 during viral infection, which could help in further unraveling the pathogenesis of SGIV.
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Affiliation(s)
- Gaochun Wu
- Institute of Marine Sciences and Guangdong Provincial Key Laboratory of Marine Biotechnology, Shantou University, Shantou 515063, China; STU-UMT Joint Shellfish Research Laboratory, Shantou University, Shantou 515063, China
| | - Qingsong Lin
- Department of Biological Sciences, Faculty of Science, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore
| | - Teck Kwang Lim
- Department of Biological Sciences, Faculty of Science, National University of Singapore, 14 Science Drive 4, Singapore 117543, Singapore
| | - Yueling Zhang
- Institute of Marine Sciences and Guangdong Provincial Key Laboratory of Marine Biotechnology, Shantou University, Shantou 515063, China; STU-UMT Joint Shellfish Research Laboratory, Shantou University, Shantou 515063, China
| | - Jude Juventus Aweya
- Institute of Marine Sciences and Guangdong Provincial Key Laboratory of Marine Biotechnology, Shantou University, Shantou 515063, China; STU-UMT Joint Shellfish Research Laboratory, Shantou University, Shantou 515063, China
| | - Jinghua Zhu
- Institute of Marine Sciences and Guangdong Provincial Key Laboratory of Marine Biotechnology, Shantou University, Shantou 515063, China; STU-UMT Joint Shellfish Research Laboratory, Shantou University, Shantou 515063, China
| | - Defu Yao
- Institute of Marine Sciences and Guangdong Provincial Key Laboratory of Marine Biotechnology, Shantou University, Shantou 515063, China; STU-UMT Joint Shellfish Research Laboratory, Shantou University, Shantou 515063, China.
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Yesilyurt A, Demirbag Z, van Oers MM, Nalcacioglu R. Conserved motifs in the invertebrate iridescent virus 6 (IIV6) genome regulate virus transcription. J Invertebr Pathol 2020; 177:107496. [PMID: 33127354 DOI: 10.1016/j.jip.2020.107496] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 10/14/2020] [Accepted: 10/20/2020] [Indexed: 10/23/2022]
Abstract
Invertebrate iridescent virus 6 (IIV6) is the type species of the Iridovirus genus in the Betairidovirinae subfamily of the Iridoviridae family. Transcription of the 215 predicted IIV6 genes is temporally regulated, dividing the genes into three kinetic classes: immediate-early (IE), delayed-early (DE), and late (L). So far, the transcriptional class has been determined for a selection of virion protein genes and only for three genes the potential promoter regions have been analyzed in detail. In this study, we investigated the transcriptional class of all IIV6 genes that had not been classified until now. RT-PCR analysis of total RNA isolated from virus-infected insect cells in the presence or absence of protein and DNA synthesis inhibitors, placed 113, 23 and 22 of the newly analyzed viral ORFs into the IE, DE and L gene classes, respectively. Afterwards, in silico analysis was performed to the upstream regions (200 bp) of all viral ORFs using the MEME Suite Software. The AA(A/T)(T/A)TG(A/G)A and (T/A/C)(T/G/C)T(T/A)ATGG motifs were identified in the upstream region of IE and DE genes, respectively. These motifs were validated by luciferase reporter assays as crucial sequences for promoter activity. For the L genes two conserved motifs were identified for all analyzed genes: (T/G)(C/T)(A/C)A(T/G/C)(T/C)T(T/C) and (C/G/T)(G/A/C)(T/A)(T/G) (G/T)(T/C). However, the presence of these two motifs did not influence promoter activity. Conversely, the presence of these two sequences upstream of the reporter decreased its expression. Single nucleotide mutations in the highly conserved nucleotides at the end of the second motif (TTGT) showed that this motif acted as a repressor sequence for late genes in the IIV6 genome. Next, upstream sequences of IIV6 L genes from which we removed this second motif in silico, were re-analyzed for the presence of potential conserved promoter sequences. Two additional motifs were identified in this way for L genes: (T/A)(A/T)(A/T/G)(A/T)(T/C)(A/G)(A/C)(A/C) and (C/G)(T/C)(T/A/C)C(A/T)(A/T)T(T/G) (T/G)(T/G/A). Independent mutations in either motif caused a severe decrease in luciferase expression. Information on temporal classes and upstream regulatory sequences will contribute to our understanding of the transcriptional mechanisms in IIV6.
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Affiliation(s)
- Aydin Yesilyurt
- Department of Biology, Faculty of Science, Karadeniz Technical University, 61080 Trabzon, Turkey; Laboratory of Virology, Wageningen University and Research, 6708 PB Wageningen, the Netherlands
| | - Zihni Demirbag
- Department of Biology, Faculty of Science, Karadeniz Technical University, 61080 Trabzon, Turkey
| | - Monique M van Oers
- Laboratory of Virology, Wageningen University and Research, 6708 PB Wageningen, the Netherlands
| | - Remziye Nalcacioglu
- Department of Biology, Faculty of Science, Karadeniz Technical University, 61080 Trabzon, Turkey
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He JH, Huang L, Guo Z, Weng S, He J, Xu X. Transcriptional programs of infectious spleen and kidney necrosis virus (ISKNV) in vitro and in vivo. Virus Genes 2020; 56:749-755. [PMID: 33033883 DOI: 10.1007/s11262-020-01800-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 09/26/2020] [Indexed: 11/26/2022]
Abstract
Infectious spleen and kidney necrosis virus (ISKNV), causing serious infectious diseases to marine and freshwater fishes, is the type species of the genus Megalocytivirus, family Iridoviridae. In this study, the transcriptional programs of ISKNV in vitro (MFF-1 cells) and in vivo (spleens from mandarin fish) were investigated using real-time PCR. Transcription of all the putative open reading frames (ORFs) of ISKNV was verified. The temporal expression patterns of ISKNV ORFs in vitro and in vivo, including peak expression times (PETs) and relative maximal expression levels, were determined and compared. The K-means clustering with Spearman rank correlation was generated in heat maps constructed based on ISKNV ORF expression profiles in vivo and in vitro. The current study may provide a global picture of ISKNV infection at the transcription level and help better understand the molecular pathogenic mechanism of megalocytiviruses.
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Affiliation(s)
- Jian-Hui He
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275, P. R. China
| | - Lichao Huang
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275, P. R. China
| | - Zhixun Guo
- South China Sea Fisheries Research Institute (CAFS), Guangzhou, PR China
| | - Shaoping Weng
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275, P. R. China
- Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-Sen University, Guangzhou, P. R. China
- Institute of Aquatic Economic Animals and Guangdong Provice Key Laboratory for Aquatic Economic Animals, Sun Yat-Sen University, Guangzhou, P. R. China
| | - Jianguo He
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275, P. R. China.
- Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-Sen University, Guangzhou, P. R. China.
- Institute of Aquatic Economic Animals and Guangdong Provice Key Laboratory for Aquatic Economic Animals, Sun Yat-Sen University, Guangzhou, P. R. China.
| | - Xiaopeng Xu
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275, P. R. China.
- Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-Sen University, Guangzhou, P. R. China.
- Institute of Aquatic Economic Animals and Guangdong Provice Key Laboratory for Aquatic Economic Animals, Sun Yat-Sen University, Guangzhou, P. R. China.
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Xia LQ, Chen JL, Zhang HL, Cai J, Zhou S, Lu YS. Identification of virion-associated transcriptional transactivator (VATT) of SGIV ICP46 promoter and their binding site on promoter. Virol J 2019; 16:110. [PMID: 31481132 PMCID: PMC6724233 DOI: 10.1186/s12985-019-1210-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 08/05/2019] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND Iridoviruses are large DNA viruses that cause diseases in fish, amphibians and insects. Singapore grouper iridovirus (SGIV) is isolated from cultured grouper and characterized as a ranavirus. ICP46 is defined to be a core gene of the family Iridoviridae and SGIV ICP46 was demonstrated to be an immediate-early (IE) gene associated with cell growth control and could contribute to virus replication in previous research. METHODS The transcription start site (TSS) and 5'-untranslated region (5'-UTR) of SGIV ICP46 were determined using 5' RACE. The core promoter elements of ICP46s were analyzed by bioinformatics analysis. The core promoter region and the regulation model of SGIV ICP46 promoter were revealed by the construction of serially deleted promoter plasmids, transfections, drug treat and luciferase reporter assays. The identification of virion-associated transcriptional transactivator (VATT) that interact with SGIV ICP46 promoter and their binding site on promoter were performed by electrophoretic mobility shift assays (EMSA), DNA pull-down assays and mass spectrometry (MS). RESULTS SGIV ICP46 was found to have short 5'-UTR and a presumptive downstream promoter element (DPE), AGACA, which locates at + 36 to + 39 nt downstream of the TSS. The core promoter region of SGIV ICP46 located from - 22 to + 42 nt relative to the TSS. VATTs were involved in the promoter activation of SGIV ICP46 and further identified to be VP12, VP39, VP57 and MCP. A 10-base DNA sequence "ATGGCTTTCG" between the TSS and presumptive DPE was determined to be the binding site of the VATTs. CONCLUSION Our study showed that four VAATs (VP12, VP39, VP57 and MCP) might bind with the SGIV ICP46 promoter and be involved in the promoter activation. Further, the binding site of the VATTs on promoter was a 10-base DNA sequence between the TSS and presumptive DPE.
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Affiliation(s)
- Li-Qun Xia
- Shenzhen Institute of Guangdong Ocean University, Shenzhen City, Guangdong, China
- College of Fisheries, Guangdong Ocean University, Zhanjiang City, Guangdong, China
- Guangdong Provincial Engineering Research Center for Aquatic Animal Health Assessment, Shenzhen Public Service Platform for Evaluation of Marine Economic Animal Seedings, Shenzhen City, Guangdong, China
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animal, Guangdong Ocean University, Zhanjiang City, Guangdong, China
| | - Jian-Lin Chen
- Shenzhen Institute of Guangdong Ocean University, Shenzhen City, Guangdong, China
- College of Fisheries, Guangdong Ocean University, Zhanjiang City, Guangdong, China
- Guangdong Provincial Engineering Research Center for Aquatic Animal Health Assessment, Shenzhen Public Service Platform for Evaluation of Marine Economic Animal Seedings, Shenzhen City, Guangdong, China
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animal, Guangdong Ocean University, Zhanjiang City, Guangdong, China
| | - Hong-Lian Zhang
- Shenzhen Institute of Guangdong Ocean University, Shenzhen City, Guangdong, China
- College of Fisheries, Guangdong Ocean University, Zhanjiang City, Guangdong, China
- Guangdong Provincial Engineering Research Center for Aquatic Animal Health Assessment, Shenzhen Public Service Platform for Evaluation of Marine Economic Animal Seedings, Shenzhen City, Guangdong, China
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animal, Guangdong Ocean University, Zhanjiang City, Guangdong, China
| | - Jia Cai
- Shenzhen Institute of Guangdong Ocean University, Shenzhen City, Guangdong, China
- College of Fisheries, Guangdong Ocean University, Zhanjiang City, Guangdong, China
- Guangdong Provincial Engineering Research Center for Aquatic Animal Health Assessment, Shenzhen Public Service Platform for Evaluation of Marine Economic Animal Seedings, Shenzhen City, Guangdong, China
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animal, Guangdong Ocean University, Zhanjiang City, Guangdong, China
| | - Sheng Zhou
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animal, Guangdong Ocean University, Zhanjiang City, Guangdong, China
- College of Marine Sciences, South China Agricultural University, Guangzhou City, Guangdong, China
| | - Yi-Shan Lu
- Shenzhen Institute of Guangdong Ocean University, Shenzhen City, Guangdong, China.
- College of Fisheries, Guangdong Ocean University, Zhanjiang City, Guangdong, China.
- Guangdong Provincial Engineering Research Center for Aquatic Animal Health Assessment, Shenzhen Public Service Platform for Evaluation of Marine Economic Animal Seedings, Shenzhen City, Guangdong, China.
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animal, Guangdong Ocean University, Zhanjiang City, Guangdong, China.
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10
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In-depth proteomic profiling of the Singapore grouper iridovirus virion. Arch Virol 2019; 164:1889-1895. [DOI: 10.1007/s00705-019-04264-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 03/29/2019] [Indexed: 11/30/2022]
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11
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Distribution and Phylogeny of Erythrocytic Necrosis Virus (ENV) in Salmon Suggests Marine Origin. Viruses 2019; 11:v11040358. [PMID: 31003511 PMCID: PMC6520742 DOI: 10.3390/v11040358] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2019] [Revised: 04/12/2019] [Accepted: 04/16/2019] [Indexed: 01/02/2023] Open
Abstract
Viral erythrocytic necrosis (VEN) affects over 20 species of marine and anadromous fishes in the North Atlantic and North Pacific Oceans. However, the distribution and strain variation of its viral causative agent, erythrocytic necrosis virus (ENV), has not been well characterized within Pacific salmon. Here, metatranscriptomic sequencing of Chinook salmon revealed that ENV infecting salmon was closely related to ENV from Pacific herring, with inferred amino-acid sequences from Chinook salmon being 99% identical to those reported for herring. Sequence analysis also revealed 89 protein-encoding sequences attributed to ENV, greatly expanding the amount of genetic information available for this virus. High-throughput PCR of over 19,000 fish showed that ENV is widely distributed in the NE Pacific Ocean and was detected in 12 of 16 tested species, including in 27% of herring, 38% of anchovy, 17% of pollock, and 13% of sand lance. Despite frequent detection in marine fish, ENV prevalence was significantly lower in fish from freshwater (0.03%), as assessed with a generalized linear mixed effects model (p = 5.5 × 10−8). Thus, marine fish are likely a reservoir for the virus. High genetic similarity between ENV obtained from salmon and herring also suggests that transmission between these hosts is likely.
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12
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Yu Y, Huang Y, Ni S, Zhou L, Liu J, Zhang J, Zhang X, Hu Y, Huang X, Qin Q. Singapore grouper iridovirus (SGIV) TNFR homolog VP51 functions as a virulence factor via modulating host inflammation response. Virology 2017; 511:280-289. [PMID: 28689858 DOI: 10.1016/j.virol.2017.06.025] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2017] [Revised: 06/19/2017] [Accepted: 06/21/2017] [Indexed: 12/15/2022]
Abstract
Virus encoded tumor necrosis factor receptor (TNFR) homologues are usually involved in immune evasion by regulating host immune response or cell death. Singapore grouper iridovirus (SGIV) is a novel ranavirus which causes great economic losses in aquaculture industry. Previous studies demonstrated that SGIV VP51, a TNFR-like protein regulated apoptotic process in VP51 overexpression cells. Here, we developed a VP51-deleted recombinant virus Δ51-SGIV by replacing VP51 with puroR-GFP. Deletion of VP51 resulted in the decrease of SGIV virulence, evidenced by the reduced replication in vitro and the decreased cumulative mortalities in Δ51-SGIV challenged grouper compared to WT-SGIV. Moreover, VP51 deletion significantly increased virus induced apoptosis, and reduced the expression of pro-inflammatory cytokines in vitro. In addition, the expression of several pro-inflammatory genes were decreased in Δ51-SGIV infected grouper compared to WT-SGIV. Thus, we speculate that SGIV VP51 functions as a critical virulence factor via regulating host cell apoptosis and inflammation response.
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Affiliation(s)
- 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, 483 Wushan Road, Guangzhou 510642, China
| | - Youhua Huang
- Joint Laboratory of Guangdong Province and Hong Kong Region on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China Agricultural University, 483 Wushan Road, Guangzhou 510642, China
| | - Songwei Ni
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lingli Zhou
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jiaxin Liu
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jingcheng Zhang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xin Zhang
- Joint Laboratory of Guangdong Province and Hong Kong Region on Marine Bioresource Conservation and Exploitation, College of Marine Sciences, South China Agricultural University, 483 Wushan Road, Guangzhou 510642, China
| | - Yin Hu
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, China; University of Chinese Academy of Sciences, Beijing 100049, 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, 483 Wushan Road, Guangzhou 510642, 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, 483 Wushan Road, Guangzhou 510642, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266000, China.
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13
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Guo M, Wei J, Zhou Y, Qin Q. c-Jun N-terminal kinases 3 (JNK3) from orange-spotted grouper, Epinephelus coioides, inhibiting the replication of Singapore grouper iridovirus (SGIV) and SGIV-induced apoptosis. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2016; 65:169-181. [PMID: 27422159 DOI: 10.1016/j.dci.2016.06.009] [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: 04/25/2016] [Revised: 06/10/2016] [Accepted: 06/10/2016] [Indexed: 06/06/2023]
Abstract
C-Jun N-terminal kinases (JNKs), a subgroup of serine-threonine protein kinases that activated by phosphorylation, are involve in physiological and pathophysiological processes. JNK3 is one of JNK proteins involved in JNK3 signaling transduction. In the present study, two JNK3 isoforms, Ec-JNK3 X1 and Ec-JNK3 X2, were cloned from orange-spotted grouper, Epinephelus coioides. Both Ec-JNK3 X1 and Ec-JNK3 X2 were mainly expressed in liver, gill, skin, brain and muscle of juvenile grouper. The relative expression of Ec-JNK3 X2 mRNA was much higher in muscle and gill than that of Ec-JNK3 X1. Isoform-specific immune response to challenges was revealed by the expression profiles in vivo. Immunofluorescence staining indicated that JNK3 was localized in the cytoplasm of grouper spleen (GS) cells and shown immune response to SGIV infection in vitro. Over-expressing Ec-JNK3 X1 and/or Ec-JNK3 X2 inhibited the SGIV infection and replication and the SGIV-induced apoptosis. To achieve the antiviral and anti-apoptosis activities, JNK3 promoted the activation of genes ISRE and type I IFN in the antiviral IFN signaling pathway, and inhibited the activation of transcription factors NF-κB and p53 relating to apoptosis, respectively. Ec-JNK3 X2 showed stronger activities in antivirus and anti-apoptosis than that of Ec-JNK3 X1. Our results not only define the characterization of JNK3 but also reveal new immune functions and the molecular mechanisms of JNK3 on iridoviruses infection and the virus-induced apoptosis.
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Affiliation(s)
- Minglan Guo
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, PR China; Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, PR China
| | - Jingguang Wei
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, PR China; Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, PR China
| | - Yongcan Zhou
- Key Laboratory of Tropical Biological Resources of Ministry of Education, Hainan University, Haikou, PR China
| | - Qiwei Qin
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, PR China; College of Marine Sciences, South China Agricultural University, Guangzhou 510642, PR China.
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14
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Guo M, Wei J, Zhou Y, Qin Q. MKK7 confers different activities to viral infection of Singapore grouper iridovirus (SGIV) and nervous necrosis virus (NNV) in grouper. FISH & SHELLFISH IMMUNOLOGY 2016; 57:419-427. [PMID: 27601297 DOI: 10.1016/j.fsi.2016.09.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 08/13/2016] [Accepted: 09/02/2016] [Indexed: 06/06/2023]
Abstract
Mitogen-activated protein kinase 7 (MKK7) is one of the major stress-activated protein kinase (SAPK)-activating kinases in response to environmental or physiological stimuli. Here a MKK7 named as Ec-MKK7 was identified from orange-spotted grouper, Epinephelus coioides. The full-length cDNA of Ec-MKK7 was 1853 bp, with an open reading frame (ORF) of 1272 bp encoding a putative protein of 423 amino acids. A characteristic S-K-A-K-T motif was contained in the domain of dual-specificity protein kinase, mitogen-activated protein kinase kinase 7 (PKc_MKK7). Intracellular localization showed that Ec-MKK7 was localized in both the cytoplasm and the nucleus of grouper spleen (GS) and/or grouper brain (EAGB) cells. Moreover, Ec-MKK7 was universally expressed in all examined tissues and showed expression modulation to challenges of lipopolysacchride (LPS), Singapore grouper iridovirus (SGIV) and polyriboinosinic polyribocytidylic acid (poly I:C) in vivo. A gene targeting strategy over-expressing Ec-MKK7 was performed to examine the activities of MKK7 to viral infection in vitro. Our data showed that Ec-MKK7 was involved in the evasion and replication of SGIV but played an antiviral role to the infection of nervous necrosis virus (NNV). All results demonstrated that Ec-MKK7 could play important roles in grouper innate immunity and show distinct functions on virus infection.
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Affiliation(s)
- Minglan Guo
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, PR China; Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, PR China
| | - Jingguang Wei
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, PR China; Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, PR China
| | - Yongcan Zhou
- State Key Laboratory of Marine Resource Utilization in South China Sea, College of Marine Science, Hainan University, Haikou, 570228, PR China.
| | - Qiwei Qin
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, PR China; College of Marine Sciences, South China Agricultural University, Guangzhou 510301, PR China.
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15
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Yuan Y, Wang Y, Liu Q, Zhu F, Hong Y. Singapore grouper iridovirus protein VP088 is essential for viral infectivity. Sci Rep 2016; 6:31170. [PMID: 27498856 PMCID: PMC4976331 DOI: 10.1038/srep31170] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 07/13/2016] [Indexed: 12/14/2022] Open
Abstract
Viral infection is a great challenge in healthcare and agriculture. The Singapore grouper iridovirus (SGIV) is highly infectious to numerous marine fishes and increasingly threatens mariculture and wildlife conservation. SGIV intervention is not available because little is known about key players and their precise roles in SGVI infection. Here we report the precise role of VP088 as a key player in SGIV infection. VP088 was verified as an envelope protein encoded by late gene orf088. We show that SGIV could be neutralized with an antibody against VP088. Depletion or deletion of VP088 significantly suppresses SGIV infection without altering viral gene expression and host responses. By precisely quantifying the genome copy numbers of host cells and virions, we reveal that VP088 deletion dramatically reduces SGIV infectivity through inhibiting virus entry without altering viral pathogenicity, genome stability and replication and progeny virus release. These results pinpoint that VP088 is a key player in SGIV entry and represents an ideal target for SGIV intervention.
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Affiliation(s)
- Yongming Yuan
- Department of Biological Sciences, National University of Singapore, Science Drive 4, Singapore 117543, Singapore
| | - Yunzhi Wang
- Department of Biological Sciences, National University of Singapore, Science Drive 4, Singapore 117543, Singapore
| | - Qizhi Liu
- Department of Biological Sciences, National University of Singapore, Science Drive 4, Singapore 117543, Singapore
| | - Feng Zhu
- Department of Biological Sciences, National University of Singapore, Science Drive 4, Singapore 117543, Singapore
| | - Yunhan Hong
- Department of Biological Sciences, National University of Singapore, Science Drive 4, Singapore 117543, Singapore
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16
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Yuan Y, Hong Y. Subcellular redistribution and sequential recruitment of macromolecular components during SGIV assembly. Protein Cell 2016; 7:651-61. [PMID: 27430948 PMCID: PMC5003786 DOI: 10.1007/s13238-016-0292-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 06/20/2016] [Indexed: 11/30/2022] Open
Abstract
Virus infection consists of entry, synthesis of macromolecular components, virus assembly and release. Understanding of the mechanisms underlying each event is necessary for the intervention of virus infection in human healthcare and agriculture. Here we report the visualization of Singapore grouper iridovirus (SGIV) assembly in the medaka haploid embryonic stem (ES) cell line HX1. SGIV is a highly infectious DNA virus that causes a massive loss in marine aquaculture. Ectopic expression of VP88GFP, a fusion between green fluorescent protein and the envelope protein VP088, did not compromise the ES cell properties and susceptibility to SGIV infection. Although VP88GFP disperses evenly in the cytoplasm of non-infected cells, it undergoes aggregation and redistribution in SGIV-infected cells. Real-time visualization revealed multiple key stages of VP88GFP redistribution and the dynamics of viral assembly site (VAS). Specifically, VP88GFP entry into and condensation in the VAS occurred within a 6-h duration, a similar duration was observed also for the release of VP88GFP-containing SGIV out of the cell. Taken together, VP088 is an excellent marker for visualizing the SGIV infection process. Our results provide new insight into macromolecular component recruitment and SGIV assembly.
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Affiliation(s)
- Yongming Yuan
- Department of Biological Sciences, National University of Singapore, Science Drive 4, Singapore, 117543, Singapore
| | - Yunhan Hong
- Department of Biological Sciences, National University of Singapore, Science Drive 4, Singapore, 117543, Singapore.
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17
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Zhang H, Zhou S, Xia L, Huang X, Huang Y, Cao J, Qin Q. Characterization of the VP39 envelope protein from Singapore grouper iridovirus. Can J Microbiol 2015; 61:924-37. [PMID: 26524136 DOI: 10.1139/cjm-2015-0118] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Singapore grouper iridovirus (SGIV) is a major pathogen that causes heavy economic losses to the grouper aquaculture industry in China and Southeast Asian countries. In the present study, a viral envelope protein, VP39, encoded by SGIV ORF39L, was identified and characterized. SGIV ORF39L was found in all sequenced iridoviruses and is now considered to be a core gene of the family Iridoviridae. ORF39L was classified as a late gene during in vitro infection using reverse transcription–polymerase chain reaction, western blotting, and a drug inhibition analysis. An indirect immunofluorescence assay revealed that the VP39 protein was confined to the cytoplasm, especially at viral assembly sites. Western blot and matrix-assisted laser desorption/ionization-time of flight tandem mass spectrometry analyses suggested that VP39 is an envelope protein. Immunogold electron microscopy further confirmed that VP39 is a viral envelope protein. Furthermore, a mouse anti-VP39 polyclonal antibody exhibited SGIV-neutralizing activity in vitro, suggesting that VP39 is involved in SGIV infection. Taken together, the current data suggest that VP39 represents a conserved envelope protein of iridoviruses that contributes to viral infection.
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Affiliation(s)
- Honglian Zhang
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, 135 West Xingang Road, Guangzhou 510275, People’s Republic of China
- College of Fishery, Guangdong Ocean University, Zhanjiang 524088, Guangdong, People’s Republic of China
| | - Sheng Zhou
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, People’s Republic of China
| | - Liqun Xia
- College of Fishery, Guangdong Ocean University, Zhanjiang 524088, Guangdong, People’s Republic of China
| | - Xiaohong Huang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, People’s Republic of China
| | - Youhua Huang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, People’s Republic of China
| | - Jianhao Cao
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, 135 West Xingang Road, Guangzhou 510275, People’s Republic of China
| | - Qiwei Qin
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, People’s Republic of China
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18
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Martín V, Mavian C, López Bueno A, de Molina A, Díaz E, Andrés G, Alcami A, Alejo A. Establishment of a Zebrafish Infection Model for the Study of Wild-Type and Recombinant European Sheatfish Virus. J Virol 2015; 89:10702-6. [PMID: 26246565 PMCID: PMC4580169 DOI: 10.1128/jvi.01580-15] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 07/29/2015] [Indexed: 01/05/2023] Open
Abstract
Amphibian-like ranaviruses include pathogens of fish, amphibians, and reptiles that have recently evolved from a fish-infecting ancestor. The molecular determinants of host range and virulence in this group are largely unknown, and currently fish infection models are lacking. We show that European sheatfish virus (ESV) can productively infect zebrafish, causing a lethal pathology, and describe a method for the generation of recombinant ESV, establishing a useful model for the study of fish ranavirus infections.
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Affiliation(s)
- Verónica Martín
- Centro de Investigación en Sanidad Animal, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Valdeolmos, Spain
| | - Carla Mavian
- Centro de Biología Molecular Severo Ochoa (Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid), Madrid, Spain
| | - Alberto López Bueno
- Centro de Biología Molecular Severo Ochoa (Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid), Madrid, Spain
| | - Antonio de Molina
- Fundación Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain
| | - Eduardo Díaz
- Fundación Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, Spain
| | - Germán Andrés
- Centro de Biología Molecular Severo Ochoa (Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid), Madrid, Spain
| | - Antonio Alcami
- Centro de Biología Molecular Severo Ochoa (Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid), Madrid, Spain
| | - Alí Alejo
- Centro de Investigación en Sanidad Animal, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Valdeolmos, Spain
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Yan Y, Guo C, Ni S, Wei J, Li P, Wei S, Cui H, Qin Q. Singapore grouper iridovirus (SGIV) encoded SGIV-miR-13 attenuates viral infection via modulating major capsid protein expression. Virus Res 2015; 205:45-53. [DOI: 10.1016/j.virusres.2015.05.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Revised: 05/05/2015] [Accepted: 05/11/2015] [Indexed: 01/07/2023]
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20
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Hu SL, Liou CJ, Cheng YH, Yiu JC, Chiou PP, Lai YS. Development and characterization of two monoclonal antibodies against grouper iridovirus 55L and 97L proteins. JOURNAL OF FISH DISEASES 2015; 38:249-258. [PMID: 24476022 DOI: 10.1111/jfd.12230] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 12/15/2013] [Accepted: 12/16/2013] [Indexed: 06/03/2023]
Abstract
Grouper iridovirus (GIV) is one of the most important viral pathogens in grouper, particularly at the fry and fingerling stages. The study of GIV pathogenicity has been hampered by the lack of proper immunological reagents to study the expression and function of viral proteins in the infected cells. In this study, two mouse monoclonal antibodies (mAbs) against GIV 55L and 97L proteins were produced. Enzyme-linked immunosorbent assay (ELISA) and Western blotting were used to screen these hybridomas, resulting in the identification of two high-affinity mAbs named GIV55L-mAb-2 and GIV97L-mAb-3, respectively. Both mAbs belong to the IgG1 isotype and were effective in detecting their respective target viral protein. Reverse-transcription polymerase chain reaction (RT-PCR) and Western blot analyses of GIV-infected GK cells revealed that GIV 97L is an immediate early gene, whereas GIV 55L a late one. The localization of 55L and 97L in GIV-infected cells was further characterized by immunofluorescence microscopy with the mAbs. The 55L protein mainly aggregated in the cytoplasm while 97L distributed in both the nucleus and cytoplasm of the infected cells. These studies demonstrate the validity of the two mAbs as immunodiagnostic and research reagents.
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Affiliation(s)
- S-L Hu
- Department of Biotechnology and Animal Science, National Ilan University, Yilan, Taiwan
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Entry of a novel marine DNA virus, Singapore grouper iridovirus, into host cells occurs via clathrin-mediated endocytosis and macropinocytosis in a pH-dependent manner. J Virol 2014; 88:13047-63. [PMID: 25165116 DOI: 10.1128/jvi.01744-14] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
UNLABELLED Iridoviruses are nucleocytoplasmic DNA viruses which cause great economic losses in the aquaculture industry but also show significant threat to global biodiversity. However, a lack of host cells has resulted in poor progress in clarifying iridovirus behavior. We investigated the crucial events during virus entry using a combination of single-virus tracking and biochemical assays, based on the established virus-cell infection model for Singapore grouper iridovirus (SGIV). SGIV infection in host cells was strongly inhibited when cells were pretreated with drugs blocking clathrin-mediated endocytosis, including sucrose and chlorpromazine. Inhibition of key regulators of macropinocytosis, including Na(+)/H(+) exchanger, Rac1 GTPase, p21-activated kinase 1 (PAK1), protein kinase C (PKC), and myosin II, significantly reduced SGIV uptake. Cy5-labeled SGIV particles were observed to colocalize with clathrin and macropinosomes. In contrast, disruption of cellular cholesterol by methyl-β-cyclodextrin and nystatin had no effect on virus infection, suggesting that SGIV entered grouper cells via the clathrin-mediated endocytic pathway and macropinocytosis but not via caveola-dependent endocytosis. Furthermore, inhibitors of endosome acidification such as chloroquine and bafilomycin A1 blocked virus infection, indicating that SGIV entered cells in a pH-dependent manner. In addition, SGIV particles were observed to be transported along both microtubules and actin filaments, and intracellular SGIV motility was remarkably impaired by depolymerization of microtubules or actin filaments. The results of this study for the first time demonstrate that not only the clathrin-dependent pathway but also macropinocytosis are involved in fish DNA enveloped virus entry, thus providing a convenient tactic for exploring the life cycle of DNA viruses. IMPORTANCE Virus entry into host cells is critically important for initiating infections and is usually recognized as an ideal target for the design of antiviral strategies. Iridoviruses are large DNA viruses which cause serious threats to ecological diversity and the aquaculture industry worldwide. However, the current understanding of iridovirus entry is limited and controversial. Singapore grouper iridovirus (SGIV) is a novel marine fish DNA virus which belongs to genus Ranavirus, family Iridoviridae. Here, using single-virus tracking technology in combination with biochemical assays, we investigated the crucial events during SGIV entry and demonstrated that SGIV entered grouper cells via the clathrin-mediated endocytic pathway in a pH-dependent manner but not via caveola-dependent endocytosis. Furthermore, we propose for the first time that macropinocytosis is involved in iridovirus entry. Together, this work not only contributes greatly to understating iridovirus pathogenesis but also provides an ideal model for exploring the behavior of DNA viruses in living cells.
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Ferreira Lacerda A, Hartjes E, Brunetti CR. LITAF mutations associated with Charcot-Marie-Tooth disease 1C show mislocalization from the late endosome/lysosome to the mitochondria. PLoS One 2014; 9:e103454. [PMID: 25058650 PMCID: PMC4110028 DOI: 10.1371/journal.pone.0103454] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Accepted: 07/02/2014] [Indexed: 01/01/2023] Open
Abstract
Charcot-Marie-Tooth (CMT) disease is one of the most common heritable neuromuscular disorders, affecting 1 in every 2500 people. Mutations in LITAF have been shown to be causative for CMT type 1C disease. In this paper we explore the subcellular localization of wild type LITAF and mutant forms of LITAF known to cause CMT1C (T49M, A111G, G112S, T115N, W116G, L122V and P135T). The results show that LITAF mutants A111G, G112S, W116G, and T115N mislocalize from the late endosome/lysosome to the mitochondria while the mutants T49M, L122V, and P135T show partial mislocalization with a portion of the total protein present in the late endosome/lysosome and the remainder of the protein localized to the mitochondria. This suggests that different mutants of LITAF will produce differing severity of disease. We also explored the effect of the presence of mutant LITAF on wild-type LITAF localization. We showed that in cells heterozygous for LITAF, CMT1C mutants T49M and G112S are dominant since wild-type LITAF localized to the mitochondria when co-transfected with a LITAF mutant. Finally, we demonstrated how LITAF transits to the endosome and mitochondria compartments of the cell. Using Brefeldin A to block ER to Golgi transport we demonstrated that wild type LITAF traffics through the secretory pathway to the late endosome/lysosome while the LITAF mutants transit to the mitochondria independent of the secretory pathway. In addition, we demonstrated that the C-terminus of LITAF is necessary and sufficient for targeting of wild-type LITAF to the late endosome/lysosome and the mutants to the mitochondria. Together these data provide insight into how mutations in LITAF cause CMT1C disease.
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Affiliation(s)
| | - Emily Hartjes
- Biology Department, Trent University, Peterborough, Ontario, Canada
| | - Craig R. Brunetti
- Biology Department, Trent University, Peterborough, Ontario, Canada
- * E-mail:
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Yan Y, Cui H, Guo C, Wei J, Huang Y, Li L, Qin Q. Singapore grouper iridovirus-encoded semaphorin homologue (SGIV-sema) contributes to viral replication, cytoskeleton reorganization and inhibition of cellular immune responses. J Gen Virol 2014; 95:1144-1155. [PMID: 24535211 DOI: 10.1099/vir.0.060608-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Semaphorins are a large, phylogenetically conserved family of proteins that are involved in a wide range of biological processes including axonal steering, organogenesis, neoplastic transformation, as well as immune responses. In this study, a novel semaphorin homologue gene belonging to the Singapore grouper iridovirus (SGIV), ORF155R (termed SGIV-sema), was cloned and characterized. The coding region of SGIV-sema is 1728 bp in length, encoding a predicted protein with 575 aa. SGIV-sema contains a ~370 aa N-terminal Sema domain, a conserved plexin-semaphorin-integrin (PSI) domain, and an immunoglobulin (Ig)-like domain near the C terminus. SGIV-sema is an early gene product during viral infection and predominantly distributed in the cytoplasm with a speckled and clubbed pattern of appearance. Functionally, SGIV-sema could promote viral replication during SGIV infection in vitro, with no effect on the proliferation of host cells. Intriguingly, ectopically expressed SGIV-sema could alter the cytoskeletal structure of fish cells, characterized by a circumferential ring of microtubules near the nucleus and a disrupted microfilament organization. Furthermore, SGIV-sema was able to attenuate the cellular immune response, as demonstrated by decreased expression of inflammation/immune-related genes such as IL-8, IL-15, TNF-α and mediator of IRF3 activation (MITA), in SGIV-sema-expressing cells before and after SGIV infection. Ultimately, our study identified a novel, functional SGIV gene that could regulate cytoskeletal structure, immune responses and facilitate viral replication.
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Affiliation(s)
- Yang Yan
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, PR China
| | - Huachun Cui
- Department of Medicine, University of Alabama at Birmingham, 901 19th Street South, Birmingham, AL 35294, USA
| | - Chuanyu Guo
- University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, PR China
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, PR China
| | - Jingguang Wei
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, PR China
| | - Youhua Huang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, PR China
| | - Lili Li
- University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, PR China
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, PR China
| | - Qiwei Qin
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, PR China
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Huang X, Gong J, Huang Y, Ouyang Z, Wang S, Chen X, Qin Q. Characterization of an envelope gene VP19 from Singapore grouper iridovirus. Virol J 2013; 10:354. [PMID: 24341864 PMCID: PMC3878628 DOI: 10.1186/1743-422x-10-354] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Accepted: 12/11/2013] [Indexed: 01/22/2023] Open
Abstract
Background Viral envelope proteins are always proposed to exert important function during virus infection and replication. Vertebrate iridoviruses are enveloped large DNA virus, which can cause great economic losses in aquaculture and ecological destruction. Although numerous iridovirus envelope proteins have been identified using bioinformatics and proteomic methods, their roles in virus infection remained largely unknown. Methods Using SMART and TMHMM programs, we investigated the structural characteristics of Singapore grouper iridovirus (SGIV) VP19. A specific antibody against VP19 was generated and the expression profile of VP19 was clarified. The subcellular localization of VP19 in the absence or presence of other viral products was determined via transfection and immune fluorescence assay. In addition, Western blot assay and electron microscopy examination were performed to demonstrate whether SGIV VP19 was an envelope protein or a capsid protein. Results Here, SGIV VP19 was cloned and characterized. Among all sequenced iridoviruses, VP19 and its orthologues shared common features, including 19 invariant cysteines, a proline-rich motif and a predicted transmembrane domain. Subsequently, the protein synthesis of VP19 was only detected at the late stage of SGIV infection and inhibited obviously by treating with AraC, confirming that VP19 was a late expressed protein. Ectopic expression of EGFP-VP19 in vitro displayed a punctate pattern in the cytoplasm. In SGIV infected cells, the newly synthesized VP19 protein was initially localized in the cytoplasm in a punctate pattern, and then aggregated into the virus assembly site at the late stage of SGIV infection, suggesting that other viral protein products were essential for VP19’s function during SGIV infection. In addition, Western blot assay and electron microscopy observation revealed that SGIV VP19 was associated with viral envelope, which was different from major capsid protein (MCP). Conclusion Taken together, the current data suggested that VP19 represented a conserved envelope protein in iridovirus, and might contribute greatly to virus assembly during virus infection.
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Affiliation(s)
| | | | | | | | | | | | - Qiwei Qin
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, China.
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Yan Y, Cui H, Guo C, Li J, Huang X, Wei J, Qin Q. An insulin-like growth factor homologue of Singapore grouper iridovirus modulates cell proliferation, apoptosis and enhances viral replication. J Gen Virol 2013; 94:2759-2770. [PMID: 24062533 DOI: 10.1099/vir.0.056135-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Insulin-like growth factors (IGFs) play crucial roles in regulating cell differentiation, proliferation and apoptosis. In this study, a novel IGF homologue gene (IGF-like) encoded by Singapore grouper iridovirus (SGIV) ORF062R (termed SGIV–IGF), was cloned and characterized. The coding region of SGIV–IGF is 771 bp in length, with a variable number of tandem repeats (VNTR) locus at the 3′-end. We cloned one isoform of this novel gene, 582 bp in length, containing the predicted IGF domain and 3.6 copy numbers of the 27 bp repeat unit. SGIV–IGF was an early transcribed gene during viral infection, and SGIV–IGF was distributed predominantly in the cytoplasm with a diffused granular appearance. Intriguingly, overexpression of SGIV–IGF was able to promote the growth of grouper embryonic cells (GP cells) by promoting G1/S phase transition, which was at least partially dependent on its 3′-end VNTR locus. Furthermore, viral titre assay and real-time quantitative PCR (RT-qPCR) analysis proved that SGIV–IGF could promote SGIV replication in grouper cells. In addition, overexpression of SGIV–IGF mildly facilitated apoptosis in SGIV-infected non-host fathead minnow (FHM) cells. Together, our study demonstrated a novel functional gene of SGIV which may regulate viral replication and cellular processes through multiple mechanisms that appear to be cell type-dependent.
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Affiliation(s)
- Yang Yan
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, PR China
| | - Huachun Cui
- Department of Medicine, University of Alabama at Birmingham, 901 19th Street South, Birmingham, AL 35294, USA
| | - Chuanyu Guo
- University of Chinese Academy of Sciences, Beijing, PR China
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, PR China
| | - Jun Li
- Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-sen University, 74 Zhongshan 2nd Road, Guangzhou 510080, PR China
| | - Xiaohong Huang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, PR China
| | - Jingguang Wei
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, PR China
| | - Qiwei Qin
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, PR China
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Zhang BC, Zhang M, Sun BG, Fang Y, Xiao ZZ, Sun L. Complete genome sequence and transcription profiles of the rock bream iridovirus RBIV-C1. DISEASES OF AQUATIC ORGANISMS 2013; 104:203-214. [PMID: 23759558 DOI: 10.3354/dao02587] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The family Iridoviridae consists of 5 genera of double-stranded DNA viruses, including the genus Megalocytivirus, which contains species that are important fish pathogens. In a previous study, we isolated the first rock bream iridovirus from China (RBIV-C1) and identified it as a member of the genus Megalocytivirus. In this report, we determined the complete genomic sequence of RBIV-C1 and examined its in vivo expression profiles. The genome of RBIV-C1 is 112333 bp in length, with a GC content of 55% and a coding density of 92%. RBIV-C1 contains 4584 simple sequence repeats, 89.8% of which are distributed among coding regions. A total of 119 potential open reading frames (ORFs) were identified in RBIV-C1, including the 26 core iridovirus genes; 41 ORFs encode proteins that are predicted to be associated with essential biological functions. RBIV-C1 exhibits the highest degree of sequence conservation and colinear arrangement of genes with orange-spotted grouper iridovirus (OSGIV) and rock bream iridovirus (RBIV). The pairwise nucleotide identities are 99.49% between RBIV-C1 and OSGIV and 98.69% between RBIV-C1 and RBIV. Compared to OSGIV, RBIV-C1 contains 11 insertions, 13 deletions, and 103 single nucleotide mutations. Whole-genome transcription analysis showed that following experimental infection of rock bream with RBIV-C1, all but 1 of the 119 ORFs were expressed at different time points and clustered into 3 hierarchical groups based on their expression patterns. These results provide new insights into the genetic nature and gene expression features of megalocytiviruses.
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Affiliation(s)
- Bao-Cun Zhang
- Institute of Oceanology, Chinese Academy of Sciences, Qingdao, People's Republic of China
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İnce İA, Özcan K, Vlak JM, van Oers MM. Temporal classification and mapping of non-polyadenylated transcripts of an invertebrate iridovirus. J Gen Virol 2013; 94:187-192. [DOI: 10.1099/vir.0.046359-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The temporal expression of the 54 Chilo iridescent virus (CIV) virion protein genes was investigated by combining drug treatments that inhibit protein or DNA synthesis and an RT-PCR strategy particularly suitable for non-polyadenylated mRNAs. This method generates a uniform 3′ terminus by ligation of a 5′-phosphorylated oligonucleotide to the 3′ end of the transcript that is recognized by a complementary primer during RT-PCR. This analysis showed that CIV virion proteins are encoded by genes in all three predetermined temporal classes: 23 immediate-early, 11 delayed-early and seven late virion gene transcripts were identified and assigned to ORFs. Early transcription of many virion protein genes supports the notion that virion proteins may also play essential roles in the initial stages of infection. In addition, some of the early gene products present in the virion may reflect the intracellular path that the virus follows during infection.
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Affiliation(s)
- İkbal Agah İnce
- Laboratory of Virology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
- Department of Genetics and Bioengineering, Yeditepe University, 34755, Istanbul, Turkey
- Department of Biosystems Engineering, Faculty of Engineering, Giresun University, 28100, Giresun, Turkey
| | - Kadriye Özcan
- Department of Biosystems Engineering, Faculty of Engineering, Giresun University, 28100, Giresun, Turkey
| | - Just M. Vlak
- Laboratory of Virology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Monique M. van Oers
- Laboratory of Virology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
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Yan Y, Cui H, Wei J, Huang Y, Huang X, Qin Q. Functional genomic studies on an immune- and antiviral-related gene of MyD88 in orange-spotted grouper, Epinephelus coioides. ACTA ACUST UNITED AC 2012. [DOI: 10.1007/s11434-012-5126-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Chinchar VG, Yu KH, Jancovich JK. The molecular biology of frog virus 3 and other iridoviruses infecting cold-blooded vertebrates. Viruses 2011; 3:1959-85. [PMID: 22069524 PMCID: PMC3205390 DOI: 10.3390/v3101959] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Revised: 09/27/2011] [Accepted: 09/27/2011] [Indexed: 01/01/2023] Open
Abstract
Frog virus 3 (FV3) is the best characterized member of the family Iridoviridae. FV3 study has provided insights into the replication of other family members, and has served as a model of viral transcription, genome replication, and virus-mediated host-shutoff. Although the broad outlines of FV3 replication have been elucidated, the precise roles of most viral proteins remain unknown. Current studies using knock down (KD) mediated by antisense morpholino oligonucleotides (asMO) and small, interfering RNAs (siRNA), knock out (KO) following replacement of the targeted gene with a selectable marker by homologous recombination, ectopic viral gene expression, and recombinant viral proteins have enabled researchers to systematically ascertain replicative- and virulence-related gene functions. In addition, the application of molecular tools to ecological studies is providing novel ways for field biologists to identify potential pathogens, quantify infections, and trace the evolution of ecologically important viral species. In this review, we summarize current studies using not only FV3, but also other iridoviruses infecting ectotherms. As described below, general principles ascertained using FV3 served as a model for the family, and studies utilizing other ranaviruses and megalocytiviruses have confirmed and extended our understanding of iridovirus replication. Collectively, these and future efforts will elucidate molecular events in viral replication, intrinsic and extrinsic factors that contribute to disease outbreaks, and the role of the host immune system in protection from disease.
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Affiliation(s)
- V Gregory Chinchar
- Department of Microbiology, University of Mississippi Medical Center, 2500 N. State Street, Jackson, MS 39216, USA.
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Zhou S, Wan Q, Huang Y, Huang X, Cao J, Ye L, Lim TK, Lin Q, Qin Q. Proteomic analysis of Singapore grouper iridovirus envelope proteins and characterization of a novel envelope protein VP088. Proteomics 2011; 11:2236-48. [DOI: 10.1002/pmic.200900820] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2009] [Revised: 02/23/2011] [Accepted: 02/28/2011] [Indexed: 11/09/2022]
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Yan Y, Cui H, Jiang S, Huang Y, Huang X, Wei S, Xu W, Qin Q. Identification of a novel marine fish virus, Singapore grouper iridovirus-encoded microRNAs expressed in grouper cells by Solexa sequencing. PLoS One 2011; 6:e19148. [PMID: 21559453 PMCID: PMC3084752 DOI: 10.1371/journal.pone.0019148] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Accepted: 03/18/2011] [Indexed: 12/03/2022] Open
Abstract
Background MicroRNAs (miRNAs) are ubiquitous non-coding RNAs that regulate gene expression at the post-transcriptional level. An increasing number of studies has revealed that viruses can also encode miRNAs, which are proposed to be involved in viral replication and persistence, cell-mediated antiviral immune response, angiogenesis, and cell cycle regulation. Singapore grouper iridovirus (SGIV) is a pathogenic iridovirus that has severely affected grouper aquaculture in China and Southeast Asia. Comprehensive knowledge about the related miRNAs during SGIV infection is helpful for understanding the infection and the pathogenic mechanisms. Methodology/Principal Findings To determine whether SGIV encoded miRNAs during infection, a small RNA library derived from SGIV-infected grouper (GP) cells was constructed and sequenced by Illumina/Solexa deep-sequencing technology. We recovered 6,802,977 usable reads, of which 34,400 represented small RNA sequences encoded by SGIV. Sixteen novel SGIV-encoded miRNAs were identified by a computational pipeline, including a miRNA that shared a similar sequence to herpesvirus miRNA HSV2-miR-H4-5p, which suggests miRNAs are conserved in far related viruses. Generally, these 16 miRNAs are dispersed throughout the SGIV genome, whereas three are located within the ORF057L region. Some SGIV-encoded miRNAs showed marked sequence and length heterogeneity at their 3′ and/or 5′ end that could modulate their functions. Expression levels and potential biological activities of these viral miRNAs were examined by stem-loop quantitative RT-PCR and luciferase reporter assay, respectively, and 11 of these viral miRNAs were present and functional in SGIV-infected GP cells. Conclusions Our study provided a genome-wide view of miRNA production for iridoviruses and identified 16 novel viral miRNAs. To the best of our knowledge, this is the first experimental demonstration of miRNAs encoded by aquatic animal viruses. The results provide a useful resource for further in-depth studies on SGIV infection and iridovirus pathogenesis.
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Affiliation(s)
- Yang Yan
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Huachun Cui
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Songshan Jiang
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Youhua Huang
- Key Laboratory of Marine Bio-resources Sustainable Utilization, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
| | - Xiaohong Huang
- Key Laboratory of Marine Bio-resources Sustainable Utilization, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
| | - Shina Wei
- Key Laboratory of Marine Bio-resources Sustainable Utilization, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
| | - Weiyi Xu
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Qiwei Qin
- Key Laboratory of Marine Bio-resources Sustainable Utilization, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- * E-mail:
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Nuclear-export-signal-dependent protein translocation of dUTPase encoded by Singapore grouper iridovirus. Arch Virol 2010; 155:1069-76. [DOI: 10.1007/s00705-010-0684-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2010] [Accepted: 04/26/2010] [Indexed: 11/25/2022]
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Wan QJ, Gong J, Huang XH, Huang YH, Zhou S, Ou-Yang ZL, Cao JH, Ye LL, Qin QW. Identification and characterization of a novel capsid protein encoded by Singapore grouper iridovirus ORF038L. Arch Virol 2010; 155:351-9. [PMID: 20130938 DOI: 10.1007/s00705-010-0594-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2009] [Accepted: 12/16/2009] [Indexed: 11/26/2022]
Abstract
Singapore grouper iridovirus (SGIV) is an important pathogen isolated from grouper, Epinephelus tauvina, and characterized as a novel ranavirus. To better understand the function of viral structural genes involved in SGIV infection and virus-host interactions, a candidate gene, VP38 (ORF038L), was investigated in this study. SGIV VP38 was found to encode a 170-aa peptide containing an RGD motif, and it showed significant identity only to members of the genus Iridovirus, family Iridoviridae, except megalocytivirus. The VP38 gene was identified by temporal expression pattern analysis and drug inhibition assay as a late (L) gene. Immunofluorescence localization revealed that P38 was distributed predominately in the cytoplasm and that association of VP38 with viral factories increased at the late stage of SGIV infection. Consistent results from immunoelectron microscopy (IEM) and western blot analysis revealed that SGIV VP38 is a viral capsid protein. Furthermore, antibodies specific for SGIV VP38 exhibited substantial SGIV-neutralizing activity in vitro, suggesting that VP38 might play an important role in SGIV infectivity.
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Affiliation(s)
- Qing Jiao Wan
- State Key Laboratory of Biocontrol, School of Life Science, Sun Yat-sen University, 135 West Xingang Road, Guangzhou, China
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Yanai-Balser GM, Duncan GA, Eudy JD, Wang D, Li X, Agarkova IV, Dunigan DD, Van Etten JL. Microarray analysis of Paramecium bursaria chlorella virus 1 transcription. J Virol 2010; 84:532-42. [PMID: 19828609 PMCID: PMC2798440 DOI: 10.1128/jvi.01698-09] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2009] [Accepted: 10/07/2009] [Indexed: 11/20/2022] Open
Abstract
Paramecium bursaria chlorella virus 1 (PBCV-1), a member of the family Phycodnaviridae, is a large double-stranded DNA, plaque-forming virus that infects the unicellular green alga Chlorella sp. strain NC64A. The 330-kb PBCV-1 genome is predicted to encode 365 proteins and 11 tRNAs. To monitor global transcription during PBCV-1 replication, a microarray containing 50-mer probes to the PBCV-1 365 protein-encoding genes (CDSs) was constructed. Competitive hybridization experiments were conducted by using cDNAs from poly(A)-containing RNAs obtained from cells at seven time points after virus infection. The results led to the following conclusions: (i) the PBCV-1 replication cycle is temporally programmed and regulated; (ii) 360 (99%) of the arrayed PBCV-1 CDSs were expressed at some time in the virus life cycle in the laboratory; (iii) 227 (62%) of the CDSs were expressed before virus DNA synthesis begins; (iv) these 227 CDSs were grouped into two classes: 127 transcripts disappeared prior to initiation of virus DNA synthesis (considered early), and 100 transcripts were still detected after virus DNA synthesis begins (considered early/late); (v) 133 (36%) of the CDSs were expressed after virus DNA synthesis begins (considered late); and (vi) expression of most late CDSs is inhibited by adding the DNA replication inhibitor, aphidicolin, prior to virus infection. This study provides the first comprehensive evaluation of virus gene expression during the PBCV-1 life cycle.
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Affiliation(s)
- Giane M. Yanai-Balser
- Department of Plant Pathology, University of Nebraska, Lincoln, Nebraska 68583-0722, Biology Department, Nebraska Wesleyan University, Lincoln, Nebraska 68504-2794, Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska 68198-5455, Statistics Department, University of Nebraska, Lincoln, Nebraska 68583-0963, Biomedical Engineering and Biotechnology, University of Massachusetts, Lowell, Massachusetts 01854, Nebraska Center for Virology, University of Nebraska, Lincoln, Nebraska 68583-0900
| | - Garry A. Duncan
- Department of Plant Pathology, University of Nebraska, Lincoln, Nebraska 68583-0722, Biology Department, Nebraska Wesleyan University, Lincoln, Nebraska 68504-2794, Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska 68198-5455, Statistics Department, University of Nebraska, Lincoln, Nebraska 68583-0963, Biomedical Engineering and Biotechnology, University of Massachusetts, Lowell, Massachusetts 01854, Nebraska Center for Virology, University of Nebraska, Lincoln, Nebraska 68583-0900
| | - James D. Eudy
- Department of Plant Pathology, University of Nebraska, Lincoln, Nebraska 68583-0722, Biology Department, Nebraska Wesleyan University, Lincoln, Nebraska 68504-2794, Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska 68198-5455, Statistics Department, University of Nebraska, Lincoln, Nebraska 68583-0963, Biomedical Engineering and Biotechnology, University of Massachusetts, Lowell, Massachusetts 01854, Nebraska Center for Virology, University of Nebraska, Lincoln, Nebraska 68583-0900
| | - Dong Wang
- Department of Plant Pathology, University of Nebraska, Lincoln, Nebraska 68583-0722, Biology Department, Nebraska Wesleyan University, Lincoln, Nebraska 68504-2794, Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska 68198-5455, Statistics Department, University of Nebraska, Lincoln, Nebraska 68583-0963, Biomedical Engineering and Biotechnology, University of Massachusetts, Lowell, Massachusetts 01854, Nebraska Center for Virology, University of Nebraska, Lincoln, Nebraska 68583-0900
| | - Xiao Li
- Department of Plant Pathology, University of Nebraska, Lincoln, Nebraska 68583-0722, Biology Department, Nebraska Wesleyan University, Lincoln, Nebraska 68504-2794, Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska 68198-5455, Statistics Department, University of Nebraska, Lincoln, Nebraska 68583-0963, Biomedical Engineering and Biotechnology, University of Massachusetts, Lowell, Massachusetts 01854, Nebraska Center for Virology, University of Nebraska, Lincoln, Nebraska 68583-0900
| | - Irina V. Agarkova
- Department of Plant Pathology, University of Nebraska, Lincoln, Nebraska 68583-0722, Biology Department, Nebraska Wesleyan University, Lincoln, Nebraska 68504-2794, Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska 68198-5455, Statistics Department, University of Nebraska, Lincoln, Nebraska 68583-0963, Biomedical Engineering and Biotechnology, University of Massachusetts, Lowell, Massachusetts 01854, Nebraska Center for Virology, University of Nebraska, Lincoln, Nebraska 68583-0900
| | - David D. Dunigan
- Department of Plant Pathology, University of Nebraska, Lincoln, Nebraska 68583-0722, Biology Department, Nebraska Wesleyan University, Lincoln, Nebraska 68504-2794, Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska 68198-5455, Statistics Department, University of Nebraska, Lincoln, Nebraska 68583-0963, Biomedical Engineering and Biotechnology, University of Massachusetts, Lowell, Massachusetts 01854, Nebraska Center for Virology, University of Nebraska, Lincoln, Nebraska 68583-0900
| | - James L. Van Etten
- Department of Plant Pathology, University of Nebraska, Lincoln, Nebraska 68583-0722, Biology Department, Nebraska Wesleyan University, Lincoln, Nebraska 68504-2794, Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, Nebraska 68198-5455, Statistics Department, University of Nebraska, Lincoln, Nebraska 68583-0963, Biomedical Engineering and Biotechnology, University of Massachusetts, Lowell, Massachusetts 01854, Nebraska Center for Virology, University of Nebraska, Lincoln, Nebraska 68583-0900
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Identification and characterization of Singapore grouper iridovirus (SGIV) ORF162L, an immediate-early gene involved in cell growth control and viral replication. Virus Res 2010; 147:30-9. [DOI: 10.1016/j.virusres.2009.09.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2009] [Revised: 09/27/2009] [Accepted: 09/28/2009] [Indexed: 11/23/2022]
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Xia L, Cao J, Huang X, Qin Q. Characterization of Singapore grouper iridovirus (SGIV) ORF086R, a putative homolog of ICP18 involved in cell growth control and virus replication. Arch Virol 2009; 154:1409-16. [PMID: 19629635 DOI: 10.1007/s00705-009-0457-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2009] [Accepted: 07/02/2009] [Indexed: 11/28/2022]
Abstract
Singapore grouper iridovirus (SGIV), as a causative agent of serious systemic disease, causes significant economic losses in grouper aquaculture. In this study, a novel ICP18 homolog encoded by SGIV ORF086R was identified and characterized. Strikingly, ICP18 homologs can be found in all ranaviruses, but not in other sequenced large DNA viruses. SGIV ICP18 is an immediate-early gene and begins to be transcribed as early as 2 h post-infection (p.i.). Western blotting indicated that SGIV ICP18 is translated as early as 6 h p.i. and is a viral non-envelope protein. Subcellular localization analysis revealed that the SGIV ICP18 displays a finely punctate cytoplasmic pattern. Furthermore, overexpression of SGIV ICP18 can promote the growth of grouper embryonic cells (GP) and contribute to SGIV replication. These results should offer important insights into the pathogenesis of ranaviruses.
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Affiliation(s)
- Liqun Xia
- State Key Laboratory of Biocontrol, School of Life Science, Sun Yat-sen University, 135 West Xingang Road, 510275, Guangzhou, China
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Majji S, Thodima V, Sample R, Whitley D, Deng Y, Mao J, Chinchar VG. Transcriptome analysis of Frog virus 3, the type species of the genus Ranavirus, family Iridoviridae. Virology 2009; 391:293-303. [PMID: 19608212 DOI: 10.1016/j.virol.2009.06.022] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2009] [Revised: 05/19/2009] [Accepted: 06/06/2009] [Indexed: 01/04/2023]
Abstract
Frog virus 3 is the best characterized species within the genus Ranavirus, family Iridoviridae. FV3's large ( approximately 105 kbp) dsDNA genome encodes 98 putative open reading frames (ORFs) that are expressed in a coordinated fashion leading to the sequential appearance of immediate early (IE), delayed early (DE) and late (L) viral transcripts. As a step toward elucidating molecular events in FV3 replication, we sought to identify the temporal class of viral messages. To accomplish this objective an oligonucleotide microarray containing 70-mer probes corresponding to each of the 98 FV3 ORFs was designed and used to examine viral gene expression. Viral transcription was initially monitored during the course of a productive replication cycle at 2, 4 and 9 h after infection. To confirm results of the time course assay, viral gene expression was also monitored in the presence of cycloheximide (CHX), which limits expression to only IE genes, and following infection with a temperature-sensitive (ts) mutant which at non-permissive temperatures is defective in viral DNA synthesis and blocked in late gene expression. Subsequently, microarray analyses were validated by RT-PCR and qRT-PCR. Using these approaches we identified 33 IE genes, 22 DE genes and 36 L viral genes. The temporal class of the 7 remaining genes could not be determined. Comparison of protein function with temporal class indicated that, in general, genes encoding putative regulatory factors, or proteins that played a part in nucleic acid metabolism and immune evasion, were classified as IE and DE genes, whereas those involved in DNA packaging and virion assembly were considered L genes. Information on temporal class will provide the basis for determining whether members of the same temporal class contain common upstream regulatory regions and perhaps allow us to identify virion-associated and virus-induced proteins that control viral gene expression.
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Affiliation(s)
- S Majji
- Department of Microbiology, University of Mississippi Medical Ctr., 2500 North State Street, Jackson, MS 39216, USA
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