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Wu Q, Ning X, Sun L. Megalocytivirus Induces Complicated Fish Immune Response at Multiple RNA Levels Involving mRNA, miRNA, and circRNA. Int J Mol Sci 2021; 22:3156. [PMID: 33808870 DOI: 10.3390/ijms22063156] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 03/16/2021] [Accepted: 03/16/2021] [Indexed: 12/22/2022] Open
Abstract
Megalocytivirus is an important viral pathogen to many farmed fishes, including Japanese flounder (Paralichthys olivaceus). In this study, we examined megalocytivirus-induced RNA responses in the spleen of flounder by high-throughput sequencing and integrative analysis of various RNA-seq data. A total of 1327 microRNAs (miRNAs), including 368 novel miRNAs, were identified, among which, 171 (named DEmiRs) exhibited significantly differential expressions during viral infection in a time-dependent manner. For these DEmiRs, 805 differentially expressed target mRNAs (DETmRs) were predicted, whose expressions not only significantly changed after megalocytivirus infection but were also negatively correlated with their paired DEmiRs. Integrative analysis of immune-related DETmRs and their target DEmiRs identified 12 hub DEmiRs, which, together with their corresponding DETmRs, formed an interaction network containing 84 pairs of DEmiR and DETmR. In addition to DETmRs, 19 DEmiRs were also found to regulate six key immune genes (mRNAs) differentially expressed during megalocytivirus infection, and together they formed a network consisting of 21 interactive miRNA-messenger RNA (mRNA) pairs. Further analysis identified 9434 circular RNAs (circRNAs), 169 of which (named DEcircRs) showed time-specific and significantly altered expressions during megalocytivirus infection. Integrated analysis of the DETmR-DEmiR and DEcircR-DEmiR interactions led to the identification of a group of competing endogenous RNAs (ceRNAs) constituted by interacting triplets of circRNA, miRNA, and mRNA involved in antiviral immunity. Together these results indicate that complicated regulatory networks of different types of non-coding RNAs and coding RNAs are involved in megalocytivirus infection.
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Girisha SK, Kushala KB, Nithin MS, Puneeth TG, Naveen Kumar BT, Vinay TN, Suresh T, Ajay SK, Venugopal MN, Ramesh KS. First report of the infectious spleen and kidney necrosis virus (ISKNV) infection in ornamental fishes in India. Transbound Emerg Dis 2020; 68:964-972. [PMID: 33448668 DOI: 10.1111/tbed.13793] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 08/09/2020] [Accepted: 08/10/2020] [Indexed: 11/29/2022]
Abstract
Infectious spleen and kidney necrosis virus (ISKNV), a member of family iridoviridae, reported for the first time in a wide range of ornamental fish species in India. Significant mortalities during the year 2018-19 were reported from a number of retailers in the region with various clinical signs. The samples of moribund, dead and apparently healthy ornamental fishes were collected from retailers, located in three districts of Karnataka, India. Out of 140 fish samples, 16 samples (11.42%) representing 10 different fish species were found positive to ISKNV by OIE listed primers and same samples were reported to amplify the major capsid protein (MCP) gene of ISKNV. Further, sequence analysis of MCP gene showed that all strains detected in this study were closely related to other documented isolates from different countries with an identity ranging from 98.76% to 100%. Further, they clustered in the clade of ISKNV, during the phylogenetic analysis. The sequence similarity was high (99.94%) to ISKNV strains from Japan, Australia and Malaysia. This is the first report of an ISKNV infection in India. Moreover, out of 10 ISKNV-positive fish species, three species were reported positive to ISKNV for the first time in the world. Further, the in vitro experiment showed the growth of virus in Asian sea bass cell line, which is a natural host of ISKNV. Therefore, considering the lethal nature of megalocytiviruses to infect a vast range of species, proper biosecurity measures need to be taken to control these emerging pathogens.
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Affiliation(s)
- S K Girisha
- College of Fisheries, Karnataka Veterinary, Animal and Fisheries Sciences University, Matsyanagar, India
| | - K B Kushala
- College of Fisheries, Karnataka Veterinary, Animal and Fisheries Sciences University, Matsyanagar, India
| | - M S Nithin
- College of Fisheries, Karnataka Veterinary, Animal and Fisheries Sciences University, Matsyanagar, India
| | - T G Puneeth
- College of Fisheries, Karnataka Veterinary, Animal and Fisheries Sciences University, Matsyanagar, India
| | - B T Naveen Kumar
- Department of Aquatic Environment, College of Fisheries, Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana, India
| | - T N Vinay
- Indian Council of Agricultural Research - Central Institute of Brackishwater Aquaculture, Chennai, India
| | - T Suresh
- College of Fisheries, Karnataka Veterinary, Animal and Fisheries Sciences University, Matsyanagar, India
| | - S K Ajay
- College of Fisheries, Karnataka Veterinary, Animal and Fisheries Sciences University, Matsyanagar, India
| | - M N Venugopal
- College of Fisheries, Karnataka Veterinary, Animal and Fisheries Sciences University, Matsyanagar, India
| | - K S Ramesh
- College of Fisheries, Karnataka Veterinary, Animal and Fisheries Sciences University, Matsyanagar, India
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Tsai JM, Huang SL, Yang CD. PCR Detection and Phylogenetic Analysis of Megalocytivirus Isolates in Farmed Giant Sea Perch Lates calcarifer in Southern Taiwan. Viruses 2020; 12:v12060681. [PMID: 32599850 PMCID: PMC7354458 DOI: 10.3390/v12060681] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 06/20/2020] [Accepted: 06/22/2020] [Indexed: 01/12/2023] Open
Abstract
The Megalocytivirus genus includes three genotypes, red sea bream iridovirus (RSIV), infectious spleen and kidney necrosis virus (ISKNV), and turbot reddish body iridovirus (TRBIV), and has caused mass mortalities in various marine and freshwater fish species in East and Southeast Asia. Of the three genotypes, TRBIV-like megalocytivirus is not included in the World Organization for Animal Health (OIE)-reportable virus list because of its geographic restriction and narrow host range. In 2017, 39 cases of suspected iridovirus infection were isolated from fingerlings of giant sea perch (Lates calcarifer) cultured in southern Taiwan during megalocytivirus epizootics. Polymerase chain reaction (PCR) with different specific primer sets was undertaken to identify the causative agent. Our results revealed that 35 out of the 39 giant sea perch iridovirus (GSPIV) isolates were TRBIV-like megalocytiviruses. To further evaluate the genetic variation, the nucleotide sequences of major capsid protein (MCP) gene (1348 bp) from 12 of the 35 TRBIV-like megalocytivirus isolates were compared to those of other known. High nucleotide sequence identity showed that these 12 TRBIV-like GSPIV isolates are the same species. Phylogenetic analysis based on the MCP gene demonstrated that these 12 isolates belong to the clade II of TRBIV megalocytiviruses, and are distinct from RSIV and ISKNV. In conclusion, the GSPIV isolates belonging to TRBIV clade II megalocytiviruses have been introduced into Taiwan and caused a severe impact on the giant sea perch aquaculture industry.
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Affiliation(s)
- Jia-Ming Tsai
- Graduate Institute of Animal Vaccine Technology, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan;
| | - Song-Lang Huang
- Pingtung County Animal Disease Control Center, Pingtung 90001, Taiwan;
| | - Chung-Da Yang
- Graduate Institute of Animal Vaccine Technology, College of Veterinary Medicine, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan;
- International Degree Program of Animal Vaccine Technology, International College, National Pingtung University of Science and Technology, Pingtung 91201, Taiwan
- Correspondence: ; Tel.: +886-8-7703-202 (ext. 5334)
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Halaly MA, Subramaniam K, Koda SA, Popov VL, Stone D, Way K, Waltzek TB. Characterization of a Novel Megalocytivirus Isolated from European Chub ( Squalius cephalus). Viruses 2019; 11:v11050440. [PMID: 31096590 PMCID: PMC6563503 DOI: 10.3390/v11050440] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 04/26/2019] [Accepted: 04/28/2019] [Indexed: 12/29/2022] Open
Abstract
A novel virus from moribund European chub (Squalius cephalus) was isolated on epithelioma papulosum cyprini (EPC) cells. Transmission electron microscopic examination revealed abundant non-enveloped, hexagonal virus particles in the cytoplasm of infected EPC cells consistent with an iridovirus. Illumina MiSeq sequence data enabled the assembly and annotation of the full genome (128,216 bp encoding 108 open reading frames) of the suspected iridovirus. Maximum Likelihood phylogenetic analyses based on 25 iridovirus core genes supported the European chub iridovirus (ECIV) as being the sister species to the recently-discovered scale drop disease virus (SDDV), which together form the most basal megalocytivirus clade. Genetic analyses of the ECIV major capsid protein and ATPase genes revealed the greatest nucleotide identity to members of the genus Megalocytivirus including SDDV. These data support ECIV as a novel member within the genus Megalocytivirus. Experimental challenge studies are needed to fulfill River’s postulates and determine whether ECIV induces the pathognomonic microscopic lesions (i.e., megalocytes with basophilic cytoplasmic inclusions) observed in megalocytivirus infections.
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Affiliation(s)
- Maya A Halaly
- Department of Animal Sciences, College of Agricultural and Life Sciences, University of Florida, Gainesville, FL 32611, USA.
| | - Kuttichantran Subramaniam
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, FL 32611, USA.
| | - Samantha A Koda
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, FL 32611, USA.
| | - Vsevolod L Popov
- Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555, USA.
| | - David Stone
- Centre for Environment, Fisheries and Aquaculture Science (CEFAS), Weymouth DT4 8UB, UK.
| | - Keith Way
- Centre for Environment, Fisheries and Aquaculture Science (CEFAS), Weymouth DT4 8UB, UK.
| | - Thomas B Waltzek
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, FL 32611, USA.
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Bermúdez R, Losada AP, de Azevedo AM, Guerra-Varela J, Pérez-Fernández D, Sánchez L, Padrós F, Nowak B, Quiroga MI. First description of a natural infection with spleen and kidney necrosis virus in zebrafish. J Fish Dis 2018; 41:1283-1294. [PMID: 29882280 DOI: 10.1111/jfd.12822] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 04/13/2018] [Accepted: 04/16/2018] [Indexed: 05/04/2023]
Abstract
Zebrafish has become a popular research model in the last years, and several diseases affecting zebrafish research facilities have been reported. However, only one case of naturally occurring viral infections was described for this species. In 2015, infectious spleen and kidney necrosis virus (ISKNV) was detected in zebrafish from a research facility in Spain. Affected fish showed lethargy, loss of appetite, abnormal swimming, distention of the coelomic cavity and, in the most severe cases, respiratory distress, pale gills and petechial haemorrhages at the base of fins. Cytomegaly was the most relevant histopathological finding in organs and tissues, sometimes associated to degenerative and necrotic changes. ISKNV belongs to the relatively newly defined genus Megalocytivirus, family Iridoviridae, comprising large, icosahedral cytoplasmic DNA viruses. This is the first case of naturally occurring Megalocytivirus infection in zebrafish research facilities, associated with morbidity. The virus has been identified based on both pathologic and genetic evidence, to better understand the pathogenesis of the infection in zebrafish and the phylogenetic relationship with other iridoviruses. Given the ability of megalocytiviruses to cross-species boundaries, it seems necessary to implement stringent biosecurity practices as these infections may invalidate experimental data and have major impact on laboratory and cultured fish.
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Affiliation(s)
- Roberto Bermúdez
- Department of Anatomy, Animal Production and Veterinary Clinical Sciences, Faculty of Veterinary, University of Santiago de Compostela, Lugo, Spain
| | - Ana Paula Losada
- Department of Anatomy, Animal Production and Veterinary Clinical Sciences, Faculty of Veterinary, University of Santiago de Compostela, Lugo, Spain
| | - Ana Manuela de Azevedo
- Department of Anatomy, Animal Production and Veterinary Clinical Sciences, Faculty of Veterinary, University of Santiago de Compostela, Lugo, Spain
| | - Jorge Guerra-Varela
- Department of Zoology, Genetics and Physical Anthropology, Faculty of Veterinary, University of Santiago de Compostela, Lugo, Spain
| | - David Pérez-Fernández
- Department of Zoology, Genetics and Physical Anthropology, Faculty of Veterinary, University of Santiago de Compostela, Lugo, Spain
| | - Laura Sánchez
- Department of Zoology, Genetics and Physical Anthropology, Faculty of Veterinary, University of Santiago de Compostela, Lugo, Spain
| | - Francesc Padrós
- Department of Animal Biology, Vegetal Biology and Ecology, Autonomous University of Barcelona, Barcelona, Spain
| | - Barbara Nowak
- Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania
| | - María Isabel Quiroga
- Department of Anatomy, Animal Production and Veterinary Clinical Sciences, Faculty of Veterinary, University of Santiago de Compostela, Lugo, Spain
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Yeh SW, Cheng YH, Nan FN, Wen CM. Characterization and virus susceptibility of a continuous cell line derived from the brain of Aequidens rivulatus (Günther). J Fish Dis 2018; 41:635-641. [PMID: 29399816 DOI: 10.1111/jfd.12763] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Revised: 11/10/2017] [Accepted: 11/10/2017] [Indexed: 06/07/2023]
Abstract
Cell cultures derived from the brain tissues of Aequidens rivulatus (Günther) have been characterized previously. In this study, a continuous cell line ARB8 was further established, and its growth characteristics, transcription and susceptibility to fish viruses-including chum salmon reovirus (CSV), marbled eel infectious pancreative necrosis virus (MEIPNV), grouper nervous necrosis virus (GNNV), giant seaperch iridovirus (GSIV), red seabream iridovirus (RSIV), koi herpesvirus (KHV), herpesvirus anguilla (HVA) and marbled eel polyoma-like virus (MEPyV)-were examined. ARB8 cells that showed epithelioid morphology and were passaged >80 times grew well at temperatures ranging from 25°C to 30°C in L-15 medium containing 5%-15% foetal bovine serum. The cells constitutively transcribed connexion 43, glutamine synthetase, nestin and nkx6-2, which are markers for neural progenitor cells. The cells were highly susceptible to CSV, MEIPNV, GSIV and RSIV and showed the typical cytopathic effect (CPE). However, the cells were resistant to GNNV, KHV, HVA and MEPyV because no significant CPE was noted after infection. Optimal temperatures for virus production ranged from 25°C to 30°C. The results revealed that the neural progenitor cell line ARB8 can potentially serve as a useful tool for investigating fish viruses and isolating new viruses in ornamental cichlid fishes.
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Affiliation(s)
- S W Yeh
- Department of Life Sciences, National University of Kaohsiung, Kaohsiung, Taiwan
| | - Y H Cheng
- Department of Biotechnology and Animal Science, National Ilan University, Ilan, Taiwan
| | - F N Nan
- Department of Aquaculture, National Taiwan Ocean University, Keelung, Taiwan
| | - C M Wen
- Department of Life Sciences, National University of Kaohsiung, Kaohsiung, Taiwan
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Jin JW, Kim YC, Hong S, Kim MS, Jeong JB, Jeong HD. Cloning and expression analysis of innate immune genes from red sea bream to assess different susceptibility to megalocytivirus infection. J Fish Dis 2017; 40:583-595. [PMID: 27523084 DOI: 10.1111/jfd.12537] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Revised: 06/20/2016] [Accepted: 06/21/2016] [Indexed: 06/06/2023]
Abstract
As suggested by the Office International des Epizooties (OIE), fishes belonging to the genus Oplegnathus are more sensitive to megalocytivirus infection than other fish species including red sea bream (Pagrus major). To assess the roles of the innate immune response to these different susceptibilities, we cloned the genes encoding inflammatory factors including IL-8 and COX-2, and the antiviral factor like Mx from red sea bream for the first time and performed phylogenetic and structural analysis. Analysed expression levels of IL-1β, IL-8 and COX-2 and the antiviral factor like Mx genes performed with in vivo challenge experiment showed no difference in inflammatory gene expression or respiratory burst activity between red sea bream and rock bream (Oplegnathus fasciatus). However, the Mx gene expression levels in red sea bream were markedly higher than those in rock bream, suggesting the importance of type I interferon (IFN)-induced proteins, particularly Mx, during megalocytivirus infection, rather than inflammation-related genes. The in vitro challenge experiments using embryonic primary cultures derived from both fish species showed no difference in cytopathic effects (CPE), viral replication profiles, and inflammatory and Mx gene expression pattern between the two fish species.
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Affiliation(s)
- J W Jin
- Namhae Fisheries Hatchery Station, Korea Fisheries Resources Agency, Wando, South Korea
| | - Y C Kim
- Department of Aquatic Life Medicine, Pukyong National University, Busan, South Korea
| | - S Hong
- Department of Marine Biotechnology, Gangneung -Wonju National University, Gangneung, South Korea
| | - M S Kim
- Pathology Division, National Fisheries Research & Development Institute, Busan, South Korea
| | - J B Jeong
- Department of Aquatic Biomedical Science, Jeju National University, Jeju, South Korea
| | - H D Jeong
- Department of Aquatic Life Medicine, Pukyong National University, Busan, South Korea
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Rimmer AE, Whittington RJ, Tweedie A, Becker JA. Susceptibility of a number of Australian freshwater fishes to dwarf gourami iridovirus (Infectious spleen and kidney necrosis virus). J Fish Dis 2017; 40:293-310. [PMID: 27334576 DOI: 10.1111/jfd.12510] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Revised: 04/27/2016] [Accepted: 04/28/2016] [Indexed: 06/06/2023]
Abstract
Megalocytiviruses cause high mortality diseases that have seriously impacted aquaculture, with the most frequent outbreaks occurring in East and South-East Asia. The international trade of juvenile fish for food and ornamental aquaculture has aided the spread of these viruses, which have spread to Europe and Australia and other regions. Australian freshwater fishes were examined for susceptibility to infection with the exotic megalocytivirus, dwarf gourami iridovirus (DGIV), which belongs to a group with the type species, Infectious spleen and kidney necrosis virus (ISKNV). Fish were held at 23 ± 1 °C and challenged by intraperitoneal (IP) injection or by cohabitation with Murray cod, Maccullochella peelii (Mitchell) infected with DGIV. A species was deemed to be susceptible to DGIV based on evidence of viral replication, as determined by qPCR, and megalocytic inclusion bodies observed histologically. Horizontal transmission occurred between infected Murray cod and golden perch, Macquaria ambigua (Richardson), Macquarie perch, Macquaria australasica (Cuvier) and Murray cod. This indicated that DGIV shed from infected fish held at 23 °C can survive in fresh water and subsequently infect these naïve fish. Further, DGIV administered IP was highly pathogenic to golden perch, Macquarie perch and Murray cod. Compared to these species, the susceptibility of southern pygmy perch, Nannoperca australis (Gunther) was lower. Freshwater catfish (dewfish), Tandanus tandanus (Mitchell), were not susceptible under the experimental conditions based on the absence of clinical disease, mortality and virus replication. This study showed the potential risks associated with naïve and DGIV-infected fish sharing a common water source.
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Affiliation(s)
- A E Rimmer
- Faculty of Veterinary Science, School of Life and Environmental Sciences, The University of Sydney, Camden, NSW, Australia
| | - R J Whittington
- Faculty of Veterinary Science, School of Life and Environmental Sciences, The University of Sydney, Camden, NSW, Australia
| | - A Tweedie
- Faculty of Veterinary Science, School of Life and Environmental Sciences, The University of Sydney, Camden, NSW, Australia
| | - J A Becker
- Faculty of Veterinary Science, School of Life and Environmental Sciences, The University of Sydney, Camden, NSW, Australia
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Wen CM. Characterization and viral susceptibility of a brain cell line from brown-marbled grouper Epinephelus fuscoguttatus (Forsskål) with persistent betanodavirus infection. J Fish Dis 2016; 39:1335-1346. [PMID: 27087415 DOI: 10.1111/jfd.12464] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 01/08/2016] [Accepted: 01/10/2016] [Indexed: 06/05/2023]
Abstract
A continuous cell line designated BMGB (brown-marbled grouper brain) was established from the brain tissues of the brown-marbled grouper Epinephelus fuscoguttatus and characterized. BMGB cells were identified as astroglial progenitor cells because they expressed glial fibrillary acidic protein and keratin and were persistently infected by betanodavirus, as confirmed through immunocytochemistry, polymerase chain reaction and immunoblot analyses. Because few intact virions were present in the BMGB cell culture fluid, the cytopathic effect (CPE) was not observed when the culture fluid was inoculated with GBC1 cells. However, BMGB cells displayed typical CPE after infection with additional betanodavirus, megalocytivirus and chum salmon reovirus. BMGB cells showed low myxovirus resistance (Mx) protein expression, which increased following betanodavirus and reovirus infection. Because the cells contained several unusual or degraded viral proteins, the persistent infection of betanodavirus in the BMGB cells may have resulted from a mechanism that destroys the viral proteins rather than the result of Mx protein expression. Despite the persistent betanodavirus infection, BMGB cells proliferated in a manner similar to other normal tropic fish cells and supported the propagation of several piscine viruses; however, the yield was lower than that of normal cells. The BMGB cells will be useful for investigating virus and host cell interaction.
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Affiliation(s)
- C M Wen
- Department of Life Sciences, National University of Kaohsiung, Kaohsiung, Taiwan.
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Jung MH, Lee J, Jung SJ. Low pathogenicity of flounder iridovirus (FLIV) and the absence of cross-protection between FLIV and rock bream iridovirus. J Fish Dis 2016; 39:1325-1333. [PMID: 27009694 DOI: 10.1111/jfd.12459] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 01/02/2016] [Accepted: 01/02/2016] [Indexed: 06/05/2023]
Abstract
The genus Megalocytivirus is known to infect a wide range of cultured marine fish. In this study, we examined the pathogenicity of FLIV (Megalocytivirus from olive flounder, genotype III) and RBIV (Megalocytivirus from rock bream, genotype I) to their homologous and heterologous host species. Olive flounder (7.5 ± 1.3 cm) injected with FLIV [major capsid protein (MCP) gene copies, 6.8 × 103 -6.5 × 106 /fish] at 24 °C did not die until 90 days post-infection (dpi). The average virus replication in the spleen peaked (1.27 × 106 /fish) at 20 dpi. Rock bream (6.5 ± 1.5 cm) injected with FLIV (8.8 × 105 and 6.5 × 106 /fish of MCP copies) showed no mortality until 50 dpi. The rock bream that survived after FLIV infection were rechallenged with RBIV at 50 dpi had 100% mortality, showing that there is no cross-protection between FLIV and RBIV. Temperature shifting (26 °C and 20 °C at 12 h intervals) did not cause FLIV-specific mortality into olive flounder, but higher virus copies were observed in the fish exposed to higher stocking density. This study demonstrates that FLIV and RBIV have different antigenic and pathogenic characteristics and that FLIV has low pathogenicity to olive flounder.
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Affiliation(s)
- M H Jung
- Department of Aqualife Medicine, Chonnam National University, Yeosu, Chonnam, Republic of Korea
| | - J Lee
- Department of Marine Life Sciences, Jeju National University, Jeju, Republic of Korea
| | - S J Jung
- Department of Aqualife Medicine, Chonnam National University, Yeosu, Chonnam, Republic of Korea.
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Jung MH, Jung SJ, Vinay TN, Nikapitiya C, Kim JO, Lee JH, Lee J, Oh MJ. Effects of water temperature on mortality in Megalocytivirus-infected rock bream Oplegnathus fasciatus (Temminck et Schlegel) and development of protective immunity. J Fish Dis 2015; 38:729-737. [PMID: 25073547 DOI: 10.1111/jfd.12286] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Revised: 05/30/2014] [Accepted: 06/05/2014] [Indexed: 06/03/2023]
Abstract
Rock bream iridovirus (RBIV) causes huge losses, especially in rock bream Oplegnathus fasciatus. Rock bream injected with RBIV and held at 29, 26, 23 or 20 °C had 100% mortality. Conversely, all infected fish held at 17 °C survived even after the temperature was progressively increased to 26 °C at 100 dpi. Rock bream exposed to virus and held for 2, 4 and 7 days at 23/26 °C before the temperature was reduced to 17 °C had mortality rates of 26.6/73.2%, 66.6/100% and 93.4/100%, respectively, through 100 dpi. When surviving fish had the water temperature increased from 17 to 26 °C at 100 dpi, they did not exhibit signs of disease and had low virus copy numbers (below 10(3)). To investigate the development of a protective immune, rock bream were infected with RBIV and held at 23 °C before shifting the water temperature to 17 °C at 4 dpi. All injected fish survived until 120 dpi. While 100% of the previously unexposed fish died, 80.2% of the previously infected fish survived. When the survivors were rechallenged again at 160 dpi, no further mortality occurred. The high survival rate of fish following rechallenge with RBIV indicates that protective immunity was established in the surviving rock bream.
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Affiliation(s)
- M H Jung
- Department of Aqualife Medicine, Chonnam National University, Yeosu, Chonnam, Korea
- Aquatic Animal Hospital, Chonnam National University, Yeosu, Chonnam, Korea
| | - S J Jung
- Department of Aqualife Medicine, Chonnam National University, Yeosu, Chonnam, Korea
- Aquatic Animal Hospital, Chonnam National University, Yeosu, Chonnam, Korea
| | - T N Vinay
- Department of Aqualife Medicine, Chonnam National University, Yeosu, Chonnam, Korea
| | - C Nikapitiya
- Department of Aqualife Medicine, Chonnam National University, Yeosu, Chonnam, Korea
| | - J O Kim
- Department of Aqualife Medicine, Chonnam National University, Yeosu, Chonnam, Korea
| | - J H Lee
- Genetic and Breeding Research Centre, National Fisheries Research and Development Institute, Koje, KyungNam, Korea
| | - J Lee
- Department of Marine Life Sciences, Jeju National University, Jeju, Korea
| | - M J Oh
- Department of Aqualife Medicine, Chonnam National University, Yeosu, Chonnam, Korea
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