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Reshi L, Wu JL, Wang HV, Hong JR. Aquatic viruses induce host cell death pathways and its application. Virus Res 2015; 211:133-44. [PMID: 26494167 DOI: 10.1016/j.virusres.2015.10.018] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 10/07/2015] [Accepted: 10/14/2015] [Indexed: 11/15/2022]
Abstract
Virus infections of mammalian and animal cells consist of a series of events. As intracellular parasites, viruses rely on the use of host cellular machinery. Through the use of cell culture and molecular approaches over the past decade, our knowledge of the biology of aquatic viruses has grown exponentially. The increase in aquaculture operations worldwide has provided new approaches for the transmission of aquatic viruses that include RNA and DNA viruses. Therefore, the struggle between the virus and the host for control of the cell's death machinery is crucial for survival. Viruses are obligatory intracellular parasites and, as such, must modulate apoptotic pathways to control the lifespan of their host to complete their replication cycle. This paper updates the discussion on the detailed mechanisms of action that various aquatic viruses use to induce cell death pathways in the host, such as Bad-mediated, mitochondria-mediated, ROS-mediated and Fas-mediated cell death circuits. Understanding how viruses exploit the apoptotic pathways of their hosts may provide great opportunities for the development of future potential therapeutic strategies and pathogenic insights into different aquatic viral diseases.
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Affiliation(s)
- Latif Reshi
- Laboratory of Molecular Virology and Biotechnology, College of Bioscience and Biotechnology, Institute of Biotechnology, National Cheng Kung University, No 1. University Road, Tainan City 701, Taiwan, ROC; Department of Life Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, No. 1. University Road, Tainan City 701, Taiwan, ROC
| | - Jen-Leih Wu
- Laboratory of Marine Molecular Biology and Biotechnology, Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei 115, Taiwan, ROC
| | - Hao-Ven Wang
- Department of Life Sciences, College of Bioscience and Biotechnology, National Cheng Kung University, No. 1. University Road, Tainan City 701, Taiwan, ROC
| | - Jiann-Ruey Hong
- Laboratory of Molecular Virology and Biotechnology, College of Bioscience and Biotechnology, Institute of Biotechnology, National Cheng Kung University, No 1. University Road, Tainan City 701, Taiwan, ROC.
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2
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Collet B. Innate immune responses of salmonid fish to viral infections. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2014; 43:160-73. [PMID: 23981327 DOI: 10.1016/j.dci.2013.08.017] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Revised: 08/19/2013] [Accepted: 08/19/2013] [Indexed: 05/07/2023]
Abstract
Viruses are the most serious pathogenic threat to the production of the main aquacultured salmonid species the rainbow trout Oncorhynchus mykiss and the Atlantic salmon Salmo salar. The viral diseases Infectious Pancreatic Necrosis (IPN), Pancreatic Disease (PD), Infectious Haemorrhagic Necrosis (IHN), Viral Haemorrhagic Septicaemia (VHS), and Infectious Salmon Anaemia (ISA) cause massive economic losses to the global salmonid aquaculture industry every year. To date, no solution exists to treat livestock affected by a viral disease and only a small number of efficient vaccines are available to prevent infection. As a consequence, understanding the host immune response against viruses in these fish species is critical to develop prophylactic and preventive control measures. The innate immune response represents an important part of the host defence mechanism preventing viral replication after infection. It is a fast acting response designed to inhibit virus propagation immediately within the host, allowing for the adaptive specific immunity to develop. It has cellular and humoral components which act in synergy. This review will cover inflammation responses, the cell types involved, apoptosis, antimicrobial peptides. Particular attention will be given to the type I interferon system as the major player in the innate antiviral defence mechanism of salmonids. Viral evasion strategies will also be discussed.
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Huang HL, Liu YT, Chen MC, Wu JL, Hong JR. Zebrafish anti-apoptotic gene Bcl-xL can prevent aquatic birnavirus-induced cell death in fish cells without affecting expression of viral proteins. FISH & SHELLFISH IMMUNOLOGY 2011; 31:970-977. [PMID: 21906684 DOI: 10.1016/j.fsi.2011.08.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Revised: 08/18/2011] [Accepted: 08/20/2011] [Indexed: 05/31/2023]
Abstract
The aquatic birnavirus induces mitochondria-mediated cell death in fish; however, the molecular mechanism remains unknown. In the present study, we demonstrated that aquatic birnavirus-induced mitochondria-mediated cell death is regulated by the anti-apoptotic Bcl-2 family member, zfBcl-xL, which is anti-apoptotic and enhances host cell viability. First, CHSE-214 cells carrying EGFP-zfBcl-xL fused genes were selected, established in culture, and used to examine the involvement of zfBcl-xL in host cell protection from the effects of viral infection. EGFP-zfBcl-xL was found to prevent infectious pancreatic necrosis virus (IPNV)-induced phosphatidylserine exposure up to 40% at 12 h and 24 h post-infection (p.i.), block IPNV-induced loss of mitochondrial membrane potential (ΔΨm), and enhance host viability at the middle and late replication stages. In addition, zfBcl-xL overexpression prevented IPNV-induced caspase-9 activation up to 25% and 85% at the middle (12 h p.i.) and late (24 h p.i.) replication stages without affecting expression of viral proteins such as VP3 (as a viral death protein) protein. In the present study, we demonstrated that aquatic birnavirus-induced cell death is prevented by the anti-apoptotic Bcl-2 family member, zfBcl-xL, which enhances host cell viability through blockage of mitochondrial disruption and caspase-9 activation.
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Affiliation(s)
- Hui-Ling Huang
- Laboratory of Molecular Virology and Biotechnology, Institute of Biotechnology, National Cheng Kung University, Tainan 701, Taiwan
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4
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Huang HL, Wu JL, Chen MHC, Hong JR. Aquatic birnavirus-induced ER stress-mediated death signaling contribute to downregulation of Bcl-2 family proteins in salmon embryo cells. PLoS One 2011; 6:e22935. [PMID: 21901118 PMCID: PMC3161983 DOI: 10.1371/journal.pone.0022935] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Accepted: 07/06/2011] [Indexed: 12/17/2022] Open
Abstract
Aquatic birnavirus induces mitochondria-mediated cell death, but whether connects to endoplasmic reticulum (ER) stress is still unknown. In this present, we characterized that IPNV infection triggers ER stress-mediated cell death via PKR/eIF2α phosphorylation signaling for regulating the Bcl-2 family protein expression in fish cells. The IPNV infection can induce ER stress as follows: (1) ER stress sensor ATF6 cleavaged; (2) ER stress marker GRP78 upregulation, and (3) PERK/eIF2α phosphorylation. Then, the IPNV-induced ER stress signals can induce the CHOP expression at early (6 h p.i.) and middle replication (12 h p.i.) stages. Moreover, IPNV-induced CHOP upregulation dramatically correlates to apparently downregulate the Bcl-2 family proteins, Bcl-2, Mcl-1 and Bcl-xL at middle replication stage (12 h p.i.) and produces mitochondria membrane potential (MMP) loss and cell death. Furthermore, with GRP78 synthesis inhibitor momitoxin (VT) and PKR inhibitor 2-aminopurine (2-AP) treatment for blocking GRP78 expression and eIF2α phosphorylation, PKR/PERK may involve in eIF2α phosphorylation/CHOP upregulation pathway that enhances the downstream regulators Bcl-2 family proteins expression and increased cell survival. Taken together, our results suggest that IPNV infection activates PKR/PERK/eIF2α ER stress signals for regulating downstream molecules CHOP upregulation and Bcl-2 family downregulation that led to induce mitochondria-mediated cell death in fish cells, which may provide new insight into RNA virus pathogenesis and disease.
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Affiliation(s)
- Hui Ling Huang
- Laboratory of Molecular Virology and Biotechnology, Institute of Biotechnology, National Cheng Kung University, Tainan, Taiwan
| | - Jen Leih Wu
- Laboratory of Marine Molecular Biology and Biotechnology, Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan
| | - Mark Hung Chih Chen
- Bioluminescence in Life-image Laboratory, Institute of Biotechnology, Department of Biotechnology, Hungkuang University, Taichung, Taiwan
- * E-mail: (JRH); (MHCC)
| | - Jiann Ruey Hong
- Laboratory of Molecular Virology and Biotechnology, Institute of Biotechnology, National Cheng Kung University, Tainan, Taiwan
- * E-mail: (JRH); (MHCC)
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5
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Wang WL, Liu W, Gong HY, Hong JR, Lin CC, Wu JL. Activation of cytokine expression occurs through the TNFα/NF-κB-mediated pathway in birnavirus-infected cells. FISH & SHELLFISH IMMUNOLOGY 2011; 31:10-21. [PMID: 21272652 DOI: 10.1016/j.fsi.2011.01.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Revised: 01/10/2011] [Accepted: 01/16/2011] [Indexed: 05/30/2023]
Abstract
The infectious pancreatic necrosis virus (IPNV) belongs to the Birnaviridae family of viruses and causes acute contagious diseases in a number of economically important freshwater and marine fish. In this study, we infected zebrafish embryonic cells (ZF4) with IPNV and analyzed the gene expression patterns of normal and infected cells using quantitative real-time PCR. We identified a number of immune response genes, including ifna, ifng, mx, irf1, irf2, irf4, tnfa, tnfb, il-1b, il-15, il-26, ccl4 and mmp family genes, that are induced after viral infection. Transcriptional regulators, including cebpb, junb, nfkb and stat1, stat4 and stat5, were also upregulated in IPNV-infected cells. In addition, we used Pathway Studio software to identify TNFα as having the greatest downstream influence among these altered genes. Treating virus-infected cells with an siRNA targeting TNFα inhibited NF-κB expression. To further interrupt the TNFα/NF-κB-mediated pathway, the expression levels of cytokines and metalloproteinases were inhibited in IPNV-infected cells. These data suggest that, during IPNV infection, the expression of cytokines and metalloproteinases might be initiated through the TNFα/NF-κB-mediated pathway. The modulation of TNFα/NF-κB-related mechanisms may provide a therapeutic strategy for inhibiting viral infection in teleosts.
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Affiliation(s)
- Wei-Lun Wang
- Institute of Cellular and Organismic Biology, Academia Sinica, Nankang 115, Taipei, Taiwan
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Wang WL, Hong JR, Lin GH, Liu W, Gong HY, Lu MW, Lin CC, Wu JL. Stage-specific expression of TNFα regulates bad/bid-mediated apoptosis and RIP1/ROS-mediated secondary necrosis in Birnavirus-infected fish cells. PLoS One 2011; 6:e16740. [PMID: 21304825 PMCID: PMC3033425 DOI: 10.1371/journal.pone.0016740] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Accepted: 01/05/2011] [Indexed: 01/18/2023] Open
Abstract
Infectious pancreatic necrosis virus (IPNV) can induce Bad-mediated apoptosis followed by secondary necrosis in fish cells, but it is not known how these two types of cell death are regulated by IPNV. We found that IPNV infection can regulate Bad/Bid-mediated apoptotic and Rip1/ROS-mediated necrotic death pathways via the up-regulation of TNFα in zebrafish ZF4 cells. Using a DNA microarray and quantitative RT-PCR analyses, two major subsets of differentially expressed genes were characterized, including the innate immune response gene TNFα and the pro-apoptotic genes Bad and Bid. In the early replication stage (0–6 h post-infection, or p.i.), we observed that the pro-inflammatory cytokine TNFα underwent a rapid six-fold induction. Then, during the early-middle replication stages (6–12 h p.i.), TNFα level was eight-fold induction and the pro-apoptotic Bcl-2 family members Bad and Bid were up-regulated. Furthermore, specific inhibitors of TNFα expression (AG-126 or TNFα-specific siRNA) were used to block apoptotic and necrotic death signaling during the early or early-middle stages of IPNV infection. Inhibition of TNFα expression dramatically reduced the Bad/Bid-mediated apoptotic and Rip1/ROS-mediated necrotic cell death pathways and rescued host cell viability. Moreover, we used Rip1-specific inhibitors (Nec-1 and Rip1-specific siRNA) to block Rip1 expression. The Rip1/ROS-mediated secondary necrotic pathway appeared to be reduced in IPNV-infected fish cells during the middle-late stage of infection (12–18 h p.i.). Taken together, our results indicate that IPNV triggers two death pathways via up-stream induction of the pro-inflammatory cytokine TNFα, and these results may provide new insights into the pathogenesis of RNA viruses.
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Affiliation(s)
- Wei-Lun Wang
- Institute of Fisheries Science, National Taiwan University, Taipei, Taiwan, Republic of China
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan, Republic of China
| | - Jiann-Ruey Hong
- Institute of Biotechnology, National Cheng Kung University, Tainan, Taiwan, Republic of China
| | - Gen-Hwa Lin
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan, Republic of China
| | - Wangta Liu
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan, Republic of China
| | - Hong-Yi Gong
- Department of Aquaculture, National Taiwan Ocean University, Keelung, Taiwan, Republic of China
| | - Ming-Wei Lu
- Department of Aquaculture, National Taiwan Ocean University, Keelung, Taiwan, Republic of China
| | - Ching-Chun Lin
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan, Republic of China
| | - Jen-Leih Wu
- Institute of Fisheries Science, National Taiwan University, Taipei, Taiwan, Republic of China
- Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, Taiwan, Republic of China
- * E-mail:
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Noguera PA, Bruno DW. Liver involvement in post-smolt Atlantic salmon, Salmo salar L., infected with infectious pancreatic necrosis virus (IPNV): a retrospective histopathological study. JOURNAL OF FISH DISEASES 2010; 33:819-832. [PMID: 20854352 DOI: 10.1111/j.1365-2761.2010.01193.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Histological changes associated with infectious pancreatic necrosis virus (IPNV) infection have historically been described for the pancreas and gut, but any involvement of the liver was poorly acknowledged or described. The aims of this study were to find robust evidence that the reported increase in liver pathology in Atlantic salmon post-smolts in natural outbreaks was effectively related to IPNV infection and retrospectively to report when such a shift in the involvement of the liver had taken place, supported by a histopathological description for a differential diagnosis. The study reports new findings concerning the dynamics of liver pathology development, with apoptosis, demonstrated by histological and immunological techniques, described as the most relevant and particular feature. Immunohistochemical examination of affected liver suggests apoptosis is not only the result of the virus infection itself but triggered through the action of the host's innate immune response. Liver involvement contributes to the nature of infection and becomes an important factor in the disease process. Additionally, it was established that the increase in infectious pancreatic necrosis prevalence is correlated with a new distinct pattern of outbreak distribution throughout the year. The role of smolt category (i.e. S1, S1/2 or S0), hence timing of seawater transfer as a strong correlating factor, is discussed.
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Affiliation(s)
- P A Noguera
- Marine Scotland, Marine Laboratory, Aberdeen, Scotland.
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8
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Sepulcre MP, Muñoz I, Roca FJ, López-Muñoz A, Mulero V. Molecular strategies used by fish pathogens to interfere with host-programmed cell death. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2010; 34:603-610. [PMID: 20097221 DOI: 10.1016/j.dci.2010.01.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Revised: 01/13/2010] [Accepted: 01/13/2010] [Indexed: 05/28/2023]
Abstract
Cell death is of pivotal importance in the regulation of the immune response and has a direct impact in disease resistance. Fish are becoming an interesting model organism to study the immune response since they hold a key phylogenetic position and many species are of high economic interest. The role of cell death in the immune response has recently been investigated in fish and the molecules and pathways orchestrating cell death in this group of animals have begun to be elucidated. In this study, we will summarize the different molecular strategies displayed by major fish bacterial and viral pathogens to interfere with programmed cell death of the host as well as the relevance of cell death in the resolution of the infectious diseases caused by these pathogens.
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Affiliation(s)
- María P Sepulcre
- Department of Cell Biology and Histology, Faculty of Biology, University of Murcia, Murcia, Spain
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Lin PY, Liu HJ, Liao MH, Chang CD, Chang CI, Cheng HL, Lee JW, Shih WL. Activation of PI 3-kinase/Akt/NF-kappaB and Stat3 signaling by avian reovirus S1133 in the early stages of infection results in an inflammatory response and delayed apoptosis. Virology 2010; 400:104-14. [PMID: 20170934 DOI: 10.1016/j.virol.2010.01.024] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2009] [Revised: 01/05/2010] [Accepted: 01/20/2010] [Indexed: 01/08/2023]
Abstract
Avian reovirus (ARV) strain S1133 causes apoptosis in host cells in the middle to late stages of infection. This study investigated the early-stage biological response and intracellular signaling in ARV S1133-infected Vero and chicken cells. Treatment with conditioned medium from ARV S1133-infected cells increased the chemotactic activity of U937 cells. Neutralizing antibodies against IL-1beta and IL-6 showed that both cytokines contribute to viral-induced inflammation but neither affect cell survival. Inhibition of Akt, NF-kappaB, and Stat3 released the chemotactic activity and anti-apoptotic effect elicited by ARV S1133. ARV S1133 activated PI 3-kinase-dependent Akt/NF-kappaB and p70 S6 kinase, as well as Stat3; however, p70 S6 kinase was not involved in ARV S1133-mediated effects. DF1 cells over-expressing constitutively active PI 3-kinase and Stat3 showed association with enhancement of anti-apoptotic activity. In conclusion, in the early stages of ARV S1133 infection, activation of cell survival signals contributes to virus-induced inflammation and anti-apoptotic response.
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Affiliation(s)
- Ping-Yuan Lin
- Graduate Institute and Department of Life Science, Tzu-Chi University, Hualien, Taiwan
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Aquatic birnavirus capsid protein, VP3, induces apoptosis via the Bad-mediated mitochondria pathway in fish and mouse cells. Apoptosis 2010; 15:653-68. [DOI: 10.1007/s10495-010-0468-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Chen PC, Wu JL, Her GM, Hong JR. Aquatic birnavirus induces necrotic cell death via the mitochondria-mediated caspase pathway. FISH & SHELLFISH IMMUNOLOGY 2010; 28:344-353. [PMID: 19944168 DOI: 10.1016/j.fsi.2009.11.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2009] [Revised: 11/05/2009] [Accepted: 11/14/2009] [Indexed: 05/28/2023]
Abstract
Aquatic birnavirus induces necrotic cell death by an ill-understood process. Presently, we demonstrate that infectious pancreatic necrosis virus (IPNV) induces post-apoptotic necrotic cell death through loss of mitochondrial membrane potential (MMP) followed by caspase-3 activation in CHSE-214 cells. Progressive phosphatidylserine externalization was observed at 6 h post-infection (p.i.). This was followed by the development of bulb-like vesicles (bleb formation) at 8 h p.i. Progressive loss of MMP was also observed in IPNV-infected CHSE-214 cells beginning at 6 h p.i. At 8 h and 12 h p.i., IPNV-infected cells demonstrated a dramatic increase in MMP loss, rapid entry into necrotic cell death, and activation of caspase-9 and -3. Additionally, treatment with an inhibitor of MMP loss, bongkrekic acid, an adenine nucleotide translocase inhibitor, blocked IPNV-induced PS exposure and MMP loss, as well as reduced the activation of caspase-3. Taken together, our results suggest that IPNV induces apoptotic cell death via loss of MMP, thereby triggering secondary necrosis and caspases-3 activation. Furthermore, this death-signaling pathway is disrupted by bongkrekic acid in fish cells, indicating that this drug may serve to modulate IPNV-induced pathogenesis.
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Affiliation(s)
- Po-Chun Chen
- Laboratory of Molecular Virology and Biotechnology, Institute of Biotechnology, National Cheng Kung University, Tainan 701, Taiwan
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Hong JR, Guan BJ, Her GM, Evensen O, Santi N, Wu JL. Aquatic birnavirus infection activates the transcription factor NF-kappaB via tyrosine kinase signalling leading to cell death. JOURNAL OF FISH DISEASES 2008; 31:451-460. [PMID: 18471101 DOI: 10.1111/j.1365-2761.2008.00928.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Our previous studies found that infectious pancreatic necrosis virus (IPNV) induces host apoptotic cell death, possibly through a newly synthesized protein trigger. Here, we examine whether IPNV infection can induce NF-kappaB activation through tyrosine kinase signalling of CHSE-214 cell death (host cell death). Using the electrophoretic mobility shift assay (EMSA) to detect transcription factor activation, we found that NF-kappaB is apparently activated 6-8 h post-IPNV infection. Using genistein (100 microg mL(-1); a tyrosine kinase inhibitor) to determine whether NF-kappaB activation requires tyrosine kinase activation, we found genistein blocks NF-kappaB activation at 8 h post-infection (p.i), and either enhances cell viability up to 50% at 12 h p.i. or blocks DNA fragmentation at 24 h p.i. Furthermore, the proteasome inhibitors PSI-I and PSI-II (both at 40 microm) also effectively blocked the NF-kappaB activation as well as stimulating a 30% increase in cell viability (30% decrease in apoptosis) at 8 and 12 h p.i. Taken together our data suggest that IPNV may induce NF-kappaB activation through tyrosine kinase signalling, which may be associated with induction of apoptosis.
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Affiliation(s)
- J-R Hong
- Laboratory of Molecular Virology and Biotechnology, Institute of Biotechnology, National Cheng-Kung University, Tainan, Taiwan
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Rønneseth A, Pettersen EF, Wergeland HI. Neutrophils and B-cells in blood and head kidney of Atlantic salmon (Salmo salar L.) challenged with infectious pancreatic necrosis virus (IPNV). FISH & SHELLFISH IMMUNOLOGY 2006; 20:610-20. [PMID: 16242964 DOI: 10.1016/j.fsi.2005.08.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2005] [Revised: 07/07/2005] [Accepted: 08/22/2005] [Indexed: 05/05/2023]
Abstract
Salmon B-cells and neutrophils were studied by flow cytometry in IPNV infected salmon. A highly virulent strain of IPNV was used for challenge of parr and post-smolts. The parr were challenged by intraperitoneal (ip) injection while salmon post-smolts were challenged by ip injection or cohabitation. No mortality occurred in the parr groups, but a cumulative mortality of about 50% was obtained in cohabitant infected post-smolt groups and less than 10% in ip challenged post-smolts. The virus levels were low in head kidney (HK) samples from survivors compared to dead fish. The percentages of neutrophilic granulocytes and Ig+ cells (B-cells) were analysed using HK and blood samples from survivors. The cell populations were identified by monoclonal antibodies (MAb) E3D9, recognising neutrophils, and G2H3 recognising Ig+ cells (B-cells). Parr sampling for leucocyte analyses took place about 1.5 weeks prior to and about 4 weeks post challenge. This corresponded to about 8 and 2.5 weeks before the fish were adapted to seawater transfer. In parr head kidney leucocytes (HKL) we observed significantly lower (p < 0.05) levels of neutrophils in ip infected fish compared to non-infected control fish. The post-smolt sampling from infected fish took place 2 weeks prior to and in the fifth and sixth week post challenge. HKL samples from both surviving cohabitants and ip injected fish had significantly (p < 0.05) lower levels of neutrophils than non-infected control fish. The cohabitant fish also had significantly (p < 0.05) higher levels of B-cells in HKL compared to ip injected fish. No significant changes in B-cells in HKL or peripheral blood leucocytes (PBL) was observed in infected parr or ip infected post-smolts compared to control fish. The relative leucocyte levels of the fish prior to challenge and in non-infected control fish are in accordance with earlier findings. The results indicate that non-specific immune cells like neutrophils are highly influenced by IPNV infection of parr and post-smolts several weeks post challenge.
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Affiliation(s)
- Anita Rønneseth
- Department of Biology, University of Bergen, Bergen High-Technology Center, PO Box 7800, N-5020 Bergen, Norway
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Hong JR, Huang LJ, Wu JL. Aquatic birnavirus induces apoptosis through activated caspase-8 and -3 in a zebrafish cell line. JOURNAL OF FISH DISEASES 2005; 28:133-140. [PMID: 15752273 DOI: 10.1111/j.1365-2761.2004.00604.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In this study, the possible influence of temperature on infectious pancreatic necrosis virus (IPNV)-induced apoptosis in a zebrafish liver epithelium (ZLE) cell line was investigated. At a lower temperature (18 degrees C), there was expression of viral proteins VP2 and VP3 at 4 h post-infection (p.i.). At this time no expression was found in the high temperature group at 28 degrees C. The cell survival ratio was 52 and 18% at 24 and 48 h p.i., respectively, during IPNV infection at 18 degrees C. In addition, we assayed for apoptosis in IPNV-infected cells with terminal deoxynucleotidyl transferase (TdT)-mediated end labelling (TUNEL) of DNA at different dosages of virus. We found a ratio of apoptotic cells of 8 and 25% at 12 and 18 h p.i., respectively, in the multiplicity of infection (MOI) 1 group. The MOI 10 group had 20 and 45% apoptotic cells at 12 and 18 h, respectively. Furthermore, at 18 degrees C IPNV activated the caspase-8 and 3 from 1.5 to 2 times at 12 and 18 h p.i., respectively. Taken together, these findings suggest that successful virus replication occurs at the low temperature (18 degrees C) compared with the non-permissive temperature of 28 degrees C. Thus, IPNV replication is capable of activating caspase-8 and -3 and inducing host apoptosis.
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Affiliation(s)
- J-R Hong
- Laboratory of Molecular Virology and Biotechnology, Institute of Biotechnology, National Cheng-Kung University, Tainan, Taiwan
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15
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Imajoh M, Hirayama T, Oshima SI. Frequent occurrence of apoptosis is not associated with pathogenic infectious pancreatic necrosis virus (IPNV) during persistent infection. FISH & SHELLFISH IMMUNOLOGY 2005; 18:163-177. [PMID: 15475312 DOI: 10.1016/j.fsi.2004.07.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2004] [Accepted: 07/01/2004] [Indexed: 05/24/2023]
Abstract
Infectious pancreatic necrosis virus (IPNV), a member of the genus Aquabirnavirus and family Birnaviridae, is an unenveloped icosahedral virus with two segments of double-stranded RNA. IPNV causes acute infection in salmonid fry and fingerlings with high mortality. However, this mortality is low as the age increases and survivors become IPNV-carrier fish. In this study, IPNV persistent infection was established in rainbow trout with no clinical signs or mortality. TUNEL staining and immunohistochemistry showed that IPNV antigen-positive cells did not have an apoptotic nucleus in almost all tissue sections and leucocyte smears, indicating that apoptosis was not induced in IPNV antigen-positive cells. The IPNV genome detected by in situ RT-PCR was more frequent than detection of the IPNV antigen by immunohistochemistry in the kidney, spleen, and liver. This result implies that the successive replication would not occur in many IPNV-infected cells. Further, apoptotic cells were predominant in the tissue sections where the signal-positive cells were frequently detected. Therefore, the presence of apoptosis in this study might be associated with host defense mechanisms, which eliminates IPNV-infected cells by the recognition of IPNV genome at the early stage of infection.
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Affiliation(s)
- Masayuki Imajoh
- Laboratory of Cell Structure and Function, Division of Marine Bioresource Science, Graduate School of Kuroshio Science, Kochi University, Nankoku Kochi 783-8502, Japan
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Espinoza JC, Cortés-Gutierrez M, Kuznar J. Necrosis of infectious pancreatic necrosis virus (IPNV) infected cells rarely is preceded by apoptosis. Virus Res 2004; 109:133-8. [PMID: 15763143 DOI: 10.1016/j.virusres.2004.10.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2004] [Revised: 10/16/2004] [Accepted: 10/16/2004] [Indexed: 11/21/2022]
Abstract
Infectious pancreatic necrosis virus (IPNV)-infected cells were labeled with Annexin V and propidium iodide in order to determine the proportion of cells, which developed necrosis and/or apoptosis during the time course of infection. Contrasting with earlier reports, we found that at any time during IPNV multiplication cycle, the percentage of apoptotic cells never exceeded the 12% of the whole population of the infected cells. In addition, the percentage of necrotic cells increased continuously until reaching the 75% of the infected cells at 15 h post infection. Apoptotic cells were also identified by in situ terminal deoxynucleotidyl transferase-mediated BrdUTP nick end labeling (TUNEL). Our results are in accordance with the idea that apoptosis rarely precedes necrosis.
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Affiliation(s)
- Juan Carlos Espinoza
- Laboratorio de Bioquímica y Virología, Instituto de Ciencias Biológicas y Químicas, Facultad de Ciencias, Casilla 50 30, Universidad de Valparaíso, Valparaíso, Chile
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17
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Villanueva RA, Galaz JL, Valdés JA, Jashés MM, Sandino AM. Genome assembly and particle maturation of the birnavirus infectious pancreatic necrosis virus. J Virol 2004; 78:13829-38. [PMID: 15564491 PMCID: PMC533905 DOI: 10.1128/jvi.78.24.13829-13838.2004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2004] [Accepted: 08/11/2004] [Indexed: 11/20/2022] Open
Abstract
In this study, we have analyzed the morphogenesis of the birnavirus infectious pancreatic necrosis virus throughout the infective cycle in CHSE-214 cells by using a native agarose electrophoresis system. Two types of viral particles (designated A and B) were identified, isolated, and characterized both molecularly and biologically. Together, our results are consistent with a model of morphogenesis in which the genomic double-stranded RNA is immediately assembled, after synthesis, into a large (66-nm diameter) and uninfectious particle A, where the capsid is composed of both mature and immature viral polypeptides. Upon maturation, particles A yield particles B through the proteolytic cleavage of most of the remaining viral precursors within the capsid, the compaction of the particle (60-nm diameter), and the acquisition of infectivity. These studies will provide the foundation for further analyses of birnavirus particle assembly and RNA replication.
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Affiliation(s)
- Rodrigo A Villanueva
- Laboratorio de Virología, Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Chile.
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18
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Lyng EM, Lyons-Alcantara M, Olwell P, Shuilleabháin SN, Seymour C, Cottell DC, Mothersill C. Ionizing radiation induces a stress response in primary cultures of rainbow trout skin. Radiat Res 2004; 162:226-32. [PMID: 15387151 DOI: 10.1667/rr3216] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Fish skin is very vulnerable to damage from physical and chemical pollutants because it is in direct contact with the aquatic environment. In this study, the effect of gamma radiation on primary cultures of rainbow trout skin was investigated. Primary cultures containing two cell types, epidermal cells and goblet mucous cells, were exposed to doses ranging from 0.5-15 Gy 60Co gamma radiation. Expression of PCNA, c-myc and BCL2 was investigated as well as growth and levels of apoptosis and necrosis. Morphological and functional changes were also studied. The irradiated cultures showed evidence of a dose-dependent increase in necrosis and enhanced proliferation as well as morphological damage. In addition, mucous cell area was found to decrease significantly after irradiation. The study shows the value of these primary cultures as in vitro models for studying radiation effects. They provide an effective alternative to whole-animal exposures for radiation risk assessment.
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Affiliation(s)
- E M Lyng
- Radiation and Environmental Science Centre, Dublin Institute of Technology, Kevin Street, Dublin 8, Ireland.
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19
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Abstract
Apoptosis (programmed cell death) is important in normal biological processes and in pathogenesis in vertebrates. This review focuses on some of the prominent features of apoptosis during fish development. Caspases and other apoptosis-regulating genes have been cloned from zebrafish (Danio rerio) and other fish species. Elucidation of in vivo functions of apoptosis is focused on development, morphogenesis and sex differentiation. In an attempt to elucidate cause and effect relationships between caspase and development, transgenic zebrafish overexpressing procaspase-3 were generated. Stress-induced apoptosis in zebrafish embryos can be monitored by whole mount TUNEL staining and caspase assay. Thus, zebrafish is a useful experimental model animal for investigation of apoptosis in vivo.
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Affiliation(s)
- Michiaki Yamashita
- National Research Institute of Fisheries Science, 2-12-4 Fukuura, Yokohama 236-8648, Japan.
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20
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Garner JN, Joshi B, Jagus R. Characterization of rainbow trout and zebrafish eukaryotic initiation factor 2alpha and its response to endoplasmic reticulum stress and IPNV infection. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2003; 27:217-231. [PMID: 12590973 DOI: 10.1016/s0145-305x(02)00096-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The cDNAs of rainbow trout and zebrafish eIF2alpha have been isolated and found to encode proteins of similar molecular weight and isoelectric point to the alpha-subunit of the human translational initiation factor, eIF2. The rainbow trout (36.0kDa) and zebrafish (36.2kDa) eIF2alphas share 93 and 91% identity to the human protein, respectively, and are recognized by antibodies raised to the human form. In mammals, the phosphorylation of the alpha-subunit of eIF2 plays a key role in the regulation of protein synthesis in response to a range of cellular stresses. Regions corresponding to the human phosphorylation and kinase-docking sites are identical in the proteins of both fish species, as are residues that interact with the eIF2 recycling factor, eIF2B. Moreover, both recombinant rainbow trout and zebrafish eIF2alphas can be phosphorylated in vitro by the mammalian heme-sensitive eIF2alpha-kinase, HRI/HCR, as well as the interferon-inducible, dsRNA sensitive kinase, PKR. Phosphorylation of rainbow trout and zebrafish eIF2alpha can also occur in vivo. RTG-2 and ZFL cells subjected to endoplasmic reticulum (ER) stress by treatment with the Ca(2+)-ionophore A23187 showed increased levels of eIF2alpha phosphorylation, suggesting similarity between the ER stress response in fish and other higher eukaryotes. Furthermore, RTG-2 cells responded to treatment with poly(I).poly(C) or to infection by infectious pancreatic necrosis virus, IPNV, by increasing eIF2alpha phosphorylation. These data imply that RTG-2 cells express the interferon-induced eIF2alpha-kinase, PKR and suggests that the interferon/eIF2alpha/PKR response to virus infection may be a conserved vertebrate characteristic. Overall these data are consistent with the premise that fish are able to regulate protein synthesis in response to cellular stresses through phosphorylation of eIF2alpha.
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Affiliation(s)
- Joseph N Garner
- Center of Marine Biotechnology, University of Maryland Biotechnology Institute, Baltimore, MD 21202, USA
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21
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Hong JR, Gong HY, Wu JL. IPNV VP5, a novel anti-apoptosis gene of the Bcl-2 family, regulates Mcl-1 and viral protein expression. Virology 2002; 295:217-29. [PMID: 12033780 DOI: 10.1006/viro.2001.1336] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
VP5, a 5'-terminal, small open reading frame in segment A of the aquatic birnavirus (infectious pancreatic necrosis virus, IPNV) genome, encodes a 17-kDa nonstructural protein. We previously reported apoptosis induced by IPNV in a fish cell line. In the present study, we cloned and identified VP5 and tested its function. Comparisons of the amino acid sequence of VP5 with well-known Bcl-2 family member proteins showed that the VP5 protein contains Bcl-2 homology (BH) domains BH1, BH2, BH3, and BH4 but without the transmembrane region. VP5-stable clones enhanced viability, prevented membrane blebbing, delayed DNA internucleosomal cleavage, and decreased virus titer during IPNV infection but, when deleted, BH domains 1 and 2 could lose the preventable ability. In addition, VP5 was demonstrated to be able to enhance or assist in maintaining the functional half-life of survival factor Mcl-1 and regulate specific viral protein expression during the early replication cycle. Finally, we found that VP5 was capable of enhancing cell viability when cells were exposed to UV irradiation. In summary, these results suggest that the aquatic birnavirus may utilize a notable strategy via VP5 to regulate the host apoptosis-off system for enhancing progeny production.
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Affiliation(s)
- Jiann-Ruey Hong
- Laboratory of Marine Molecular Biology and Biotechnology, Institute of Zoology, Academia Sinica, Nankang, Taipei 115, Taiwan, ROC
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22
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Hong JR, Wu JL. Induction of apoptotic death in cells via Bad gene expression by infectious pancreatic necrosis virus infection. Cell Death Differ 2002; 9:113-24. [PMID: 11840162 DOI: 10.1038/sj.cdd.4400933] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2001] [Revised: 05/23/2001] [Accepted: 07/19/2001] [Indexed: 11/09/2022] Open
Abstract
A Bcl-2 related family member, Bad, promotes cell death, and its function is regulated by phosphorylation. In this study, we show how the IPNV elicits the induction of Bad gene expression and promotes host apoptotic death. Anti-IPNV-E1S polyclonal and anti-VP3 monoclonal antibodies are used to neutralize the virus that blocks the prime death signal via the virus receptor. In the viability assay, each antibody could also enhance cell viability during IPNV infection. We tested tyrosine kinase inhibitors on IPNV-infected cells in order to assess their effect on blocking the death signal. With 100 microg/ml genistein treatment, Bad-like gene expression was blocked, either by rescuing the IPNV-infected CHSE-214 cells or by blocking internucleosomal DNA cleavage; but the tyrphostin group did not block Bad expression. For CHSE-214 cells, treatment with the protein synthesis-inhibitor, cycloheximide (1microg/ml), blocked new protein synthesis via activated tyrosine kinase during IPNV infection. We found that Bad protein expression could be blocked, and apoptotic death prevented. Together, these results demonstrate that the IPNV exerts up-regulation of a pro-apoptotic death gene (Bad), the expression of which serves to trigger apoptotic cell death. Our data also suggests that the IPNV induces apoptotic death via a viral receptor which triggers death effector Bad gene expression, possibly through a tyrosine kinase-dependent pathway.
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Affiliation(s)
- J-R Hong
- Laboratory of Marine Molecular Biology and Biotechnology, Institute of Zoology, Academia Sinica, Nankang, Taipei 115, Taiwan
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23
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Evans DL, Leary JH, Jaso-Friedmann L. Nonspecific cytotoxic cells and innate immunity: regulation by programmed cell death. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2001; 25:791-805. [PMID: 11602196 DOI: 10.1016/s0145-305x(01)00036-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Although programmed cell death (PCD) and the cellular pathology of apoptosis have been extensively studied in mammals and invertebrates, little is known regarding these important regulatory processes in cold blooded vertebrates, especially teleost fish. In the present review, select immunoregulatory properties of PCD/apoptosis in nonspecific cytotoxic cells (NCC) from catfish and tilapia were identified. The techniques used to define the characteristics of PCD in NCC were DNA ploidy, Annexin-V binding and cellular morphology. Using these procedures, we determined that the biochemical/genetic changes that NCC undergo during PCD are similar to those described in mammalian cells. We hypothesize that one immediate response of NCC to acute stress in teleost fish is the release of apoptosis regulatory factors (ARF) or stress activated serum factors (SASF) into the peripheral blood. These cytokine-like factors activate NCC by protecting them from initiation of: "activation induced cell death" (AICD); from "receptor induced apoptosis"; and from initiation of dexamethasone induced DNA hypoploidy. We predict that the mechanism of these actions is enhanced NCC recycling capacity and initiation of migration of NCC into sites of inflammation. In this review, studies were also summarized regarding the expression and release of "death and survival proteins" by NCC. Although the survey was not exhaustive, we showed that tilapia NCC that were activated in vitro with SASF contained increased levels of two adaptor proteins (i.e. CAS, FADD) and soluble FasL. At present the relevance of expression of the adaptor proteins by NCC is not known, however, additional evidence for the role of FasL in NCC innate immune responses was presented. Interestingly, NCC contained constitutive cytosolic FasL, and activation with tumor cells caused a significant decrease in the cytoplasmic levels of this "death protein". This indicated that FasL in NCC may function as a secretory cytokine-like molecule. Unlike mammalian NK cells and T-cells, activated NCC do not express membrane FasL. A level of phosphatase regulation of NCC apoptosis was indicated by demonstrating a reduced camptothecin induce DNA hypoploidy by pretreatment of NCC with the tyrosine phosphatase inhibitor sodium orthovanadate. This review emphasized the important regulatory functions of PCD/apoptosis for NCC in innate immune responses.
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Affiliation(s)
- D L Evans
- Department of Medical Microbiology and Parasitology, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA.
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24
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Essbauer S, Ahne W. Viruses of lower vertebrates. JOURNAL OF VETERINARY MEDICINE. B, INFECTIOUS DISEASES AND VETERINARY PUBLIC HEALTH 2001; 48:403-75. [PMID: 11550762 PMCID: PMC7159363 DOI: 10.1046/j.1439-0450.2001.00473.x] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Viruses of lower vertebrates recently became a field of interest to the public due to increasing epizootics and economic losses of poikilothermic animals. These were reported worldwide from both wildlife and collections of aquatic poikilothermic animals. Several RNA and DNA viruses infecting fish, amphibians and reptiles have been studied intensively during the last 20 years. Many of these viruses induce diseases resulting in important economic losses of lower vertebrates, especially in fish aquaculture. In addition, some of the DNA viruses seem to be emerging pathogens involved in the worldwide decline in wildlife. Irido-, herpes- and polyomavirus infections may be involved in the reduction in the numbers of endangered amphibian and reptile species. In this context the knowledge of several important RNA viruses such as orthomyxo-, paramyxo-, rhabdo-, retro-, corona-, calici-, toga-, picorna-, noda-, reo- and birnaviruses, and DNA viruses such as parvo-, irido-, herpes-, adeno-, polyoma- and poxviruses, is described in this review.
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Affiliation(s)
- S Essbauer
- WHO Centre for Comparative Virology, Institute of Medical Microbiology, Infectious and Epidemic Diseases, Ludwig-Maximilians-Universität, Munich, Germany.
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25
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Eléouët JF, Druesne N, Chilmonczyk S, Monge D, Dorson M, Delmas B. Comparative study of in-situ cell death induced by the viruses of viral haemorrhagic septicaemia (VHS) and infectious pancreatic necrosis (IPN) in rainbow trout. J Comp Pathol 2001; 124:300-7. [PMID: 11437506 DOI: 10.1053/jcpa.2001.0467] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The causative viruses of two diseases of rainbow trout, viral haemorrhagic septicaemia (VHS) and infectious pancreatic necrosis (IPN), exert much of their cytopathogenic effect in cell culture through the induction of apoptosis. In the present study, the TUNEL procedure was used to investigate the presence of apoptotic cells in different organs of rainbow trout infected with the viruses of VHS and IPN. VHS viral infection resulted in massive apoptosis in renal lymphoid tissue, where viral antigens were also detected. Large numbers of viral particles were observed in close proximity to apoptotic cells. Apoptosis was not detected in excretory cells of the renal tubules or in infected muscle cells. IPN virus did not induce apoptosis in the pancreas. However, the DNA degradation associated with apoptotic nuclei was observed in muscle lesions. Taken together, these results indicated that induction of apoptosis in vivo was critically influenced by the species of virus and the cell type. Moreover, it would seem likely that apoptosis contributed to the nature of the two diseases and to mortality.
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Affiliation(s)
- J F Eléouët
- UnitAe de Virologie et Immunologie Moléculaires, Institut National de la Recherche Agronomique, Jouy-en-Josas, 78352, France
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26
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Laing KJ, Holland J, Bonilla S, Cunningham C, Secombes CJ. Cloning and sequencing of caspase 6 in rainbow trout, Oncorhynchus mykiss, and analysis of its expression under conditions known to induce apoptosis. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2001; 25:303-312. [PMID: 11246070 DOI: 10.1016/s0145-305x(00)00061-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The rainbow trout caspase 6 gene has been cloned and sequenced. The open reading frame consisted of 906bp, which translated into a protein of 302 amino acids, containing the caspase active site pentapeptide (QACRG) and the caspase family signature (HADADCFVCVFLSHG). Amino acids involved in catalysis and those known to form the P1 carbohydrate binding pocket were conserved. Phylogenetic tree analysis showed a tight grouping with other known caspase 6 genes. Conserved aspartic acid residues at positions 33, 191 and 202 suggested that this molecule is produced as a proenzyme that is subsequently cleaved to release active subunits, with the region between Asp-191 and Ala-203 acting as a linker that is cleaved out. RT-PCR analysis revealed that the trout caspase 6 gene was expressed in brain, blood, gill, liver, head kidney and spleen. Addition of LPS or cortisol to head kidney leucocyte cultures had no effect upon caspase 6 expression. However, addition of LPS after preincubation with cortisol increased expression relative to control cultures. Incubation with RU486 abrogated this effect, confirming it was mediated via glucocorticoid receptors. Lastly, a confinement stress in vivo increased caspase 6 expression. The data are discussed with respect to the immunoregulatory role of apoptosis in fish immune responses.
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Affiliation(s)
- K J Laing
- Department of Zoology, University of Aberdeen, Tillydrone Avenue, Aberdeen AB24 2TZ, UK
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27
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Abstract
Apoptosis is a form of programmed cell death that is essential for the development of the embryo and adult tissue plasticity. In adults, it is observed mainly in those tissues undergoing active differentiation such as the hematopoietic system, testis, ovary, and intestinal epithelium. Apoptosis can be triggered by many factors, such as hormones, cytokines, and drugs, depending on the type of the cell. While the intracellular signaling mechanisms may vary in different cells, they all display similar morphological and biochemical features at the later stages of the apoptotic process. This review focuses on the factors controlling ovarian apoptosis, emphasizing observations made on GnRH-induced apoptotic process in goldfish follicles.Key words: apoptosis, ovary, GnRH.
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