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Moreno P, Gemez-Mata J, Alvarez-Torres D, Garcia-Rosado E, Bejar J, Alonso MC. Genomic characterization and transcription analysis of European sea bass (Dicentrarchus labrax) rtp3 genes. Mol Immunol 2023; 163:243-248. [PMID: 37879238 DOI: 10.1016/j.molimm.2023.10.009] [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: 07/20/2023] [Revised: 10/03/2023] [Accepted: 10/16/2023] [Indexed: 10/27/2023]
Abstract
Fish RTP3, belonging to the receptor-transporting protein family, display several functions, including a putative antiviral role as virus-responsive gene. In this work, we have identified and characterized two different European sea bass rtp3 genes. In addition, an in vivo transcription analysis in response to LPS, poly I:C and betanodavirus infection (RGNNV genotype) has been performed. The sequence analysis showed that European sea bass displays two rtp3 genes, X1 and X2, composed of two exons and a single intron (1007-bp and 888-bp long, respectively), located within the ORF sequence. The full-length cDNA is 1969 bp for rtp3 X1, and 1491 bp for rtp3 X2. Several ATTTA motifs have been found in the intron sequence of both genes, whereas rtp3 X1 also contains this motif in both untranslated regions. The transcription analyses revealed significant level of rtp3 X2 mRNA in brain and head kidney after LPS and poly I:C inoculation; however, the induction elicited by RGNNV infection was much higher, suggesting an essential role for this protein in controlling NNV infections.
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Affiliation(s)
- Patricia Moreno
- Universidad de Málaga, Instituto de Biotecnología y Desarrollo Azul (IBYDA), Departamento de Microbiología, Facultad de Ciencias, 29071 Málaga, Spain
| | - Juan Gemez-Mata
- Universidad de Málaga, Instituto de Biotecnología y Desarrollo Azul (IBYDA), Departamento de Microbiología, Facultad de Ciencias, 29071 Málaga, Spain
| | - Daniel Alvarez-Torres
- Universidad de Málaga, Instituto de Biotecnología y Desarrollo Azul (IBYDA), 29071 Málaga, Spain
| | - Esther Garcia-Rosado
- Universidad de Málaga, Instituto de Biotecnología y Desarrollo Azul (IBYDA), Departamento de Microbiología, Facultad de Ciencias, 29071 Málaga, Spain
| | - Julia Bejar
- Universidad de Málaga, Instituto de Biotecnología y Desarrollo Azul (IBYDA), Departamento de Biología Celular, Genética y Fisiología, Facultad de Ciencias, 29071 Málaga, Spain
| | - M Carmen Alonso
- Universidad de Málaga, Instituto de Biotecnología y Desarrollo Azul (IBYDA), Departamento de Microbiología, Facultad de Ciencias, 29071 Málaga, Spain.
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2
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Ortega-del Campo S, Díaz-Martínez L, Moreno P, García-Rosado E, Alonso MC, Béjar J, Grande-Pérez A. The genetic variability and evolution of red-spotted grouper nervous necrosis virus quasispecies can be associated with its virulence. Front Microbiol 2023; 14:1182695. [PMID: 37396376 PMCID: PMC10308047 DOI: 10.3389/fmicb.2023.1182695] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Accepted: 05/23/2023] [Indexed: 07/04/2023] Open
Abstract
Nervous necrosis virus, NNV, is a neurotropic virus that causes viral nervous necrosis disease in a wide range of fish species, including European sea bass (Dicentrarchus labrax). NNV has a bisegmented (+) ssRNA genome consisting of RNA1, which encodes the RNA polymerase, and RNA2, encoding the capsid protein. The most prevalent NNV species in sea bass is red-spotted grouper nervous necrosis virus (RGNNV), causing high mortality in larvae and juveniles. Reverse genetics studies have associated amino acid 270 of the RGNNV capsid protein with RGNNV virulence in sea bass. NNV infection generates quasispecies and reassortants able to adapt to various selective pressures, such as host immune response or switching between host species. To better understand the variability of RGNNV populations and their association with RGNNV virulence, sea bass specimens were infected with two RGNNV recombinant viruses, a wild-type, rDl956, highly virulent to sea bass, and a single-mutant virus, Mut270Dl965, less virulent to this host. Both viral genome segments were quantified in brain by RT-qPCR, and genetic variability of whole-genome quasispecies was studied by Next Generation Sequencing (NGS). Copies of RNA1 and RNA2 in brains of fish infected with the low virulent virus were 1,000-fold lower than those in brains of fish infected with the virulent virus. In addition, differences between the two experimental groups in the Ts/Tv ratio, recombination frequency and genetic heterogeneity of the mutant spectra in the RNA2 segment were found. These results show that the entire quasispecies of a bisegmented RNA virus changes as a consequence of a single point mutation in the consensus sequence of one of its segments. Sea bream (Sparus aurata) is an asymptomatic carrier for RGNNV, thus rDl965 is considered a low-virulence isolate in this species. To assess whether the quasispecies characteristics of rDl965 were conserved in another host showing different susceptibility, juvenile sea bream were infected with rDl965 and analyzed as above described. Interestingly, both viral load and genetic variability of rDl965 in seabream were similar to those of Mut270Dl965 in sea bass. This result suggests that the genetic variability and evolution of RGNNV mutant spectra may be associated with its virulence.
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Affiliation(s)
- Sergio Ortega-del Campo
- Departamento de Biología Celular, Genética y Fisiología, Facultad de Ciencias, Universidad de Málaga, Málaga, Spain
| | - Luis Díaz-Martínez
- Centro de Supercomputación y Bioinnovación (SCBI), Universidad de Málaga, Málaga, Spain
| | - Patricia Moreno
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga, Málaga, Spain
- Instituto de Biotecnología y Desarrollo Azul, IBYDA, Universidad de Málaga, Málaga, Spain
| | - Esther García-Rosado
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga, Málaga, Spain
- Instituto de Biotecnología y Desarrollo Azul, IBYDA, Universidad de Málaga, Málaga, Spain
| | - M. Carmen Alonso
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga, Málaga, Spain
- Instituto de Biotecnología y Desarrollo Azul, IBYDA, Universidad de Málaga, Málaga, Spain
| | - Julia Béjar
- Departamento de Biología Celular, Genética y Fisiología, Facultad de Ciencias, Universidad de Málaga, Málaga, Spain
- Instituto de Biotecnología y Desarrollo Azul, IBYDA, Universidad de Málaga, Málaga, Spain
| | - Ana Grande-Pérez
- Departamento de Biología Celular, Genética y Fisiología, Facultad de Ciencias, Universidad de Málaga, Málaga, Spain
- Instituto de Hortofruticultura Subtropical y Mediterránea “La Mayora”, Universidad de Málaga- Consejo Superior de Investigaciones Científicas (IHSM-UMA-CSIC), Málaga, Spain
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3
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Mao M, Jiang J, Xu J, Liu Y, Wang H, Mao Y. Cells and Fugu Response to Capsid of BFNNV Genotype. Viruses 2023; 15:v15040988. [PMID: 37112968 PMCID: PMC10142826 DOI: 10.3390/v15040988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 04/13/2023] [Accepted: 04/14/2023] [Indexed: 04/29/2023] Open
Abstract
The nervous necrosis virus (NNV) of the BFNNV genotype is the causative agent of viral encephalopathy and retinopathy (VER) in cold water fishes. Similar to the RGNNV genotype, BFNNV is also considered a highly destructive virus. In the present study, the RNA2 of the BFNNV genotype was modified and expressed in the EPC cell line. The subcellular localization results showed that the capsid and N-terminal (1-414) were located in the nucleus, while the C-terminal (415-1014) of the capsid was located in the cytoplasm. Meanwhile, cell mortality obviously increased after expression of the capsid in EPC. EPC cells were transfected with pEGFP-CP and sampled at 12 h, 24 h and 48 h for transcriptome sequencing. There are 254, 2997 and 229 up-regulated genes and 387, 1611, and 649 down-regulated genes post-transfection, respectively. The ubiquitin-activating enzyme and ubiquitin-conjugating enzyme were up-regulated in the DEGs, indicating that cell death evoked by capsid transfection may be related to ubiquitination. The qPCR results showed that heat stock protein 70 (HSP70) is extremely up-regulated after expression of BFNNV capsid in EPC, and N-terminal is the key region to evoke the high expression. For further study, the immunoregulation of the capsid in fish pcDNA-3.1-CP was constructed and injected into the Takifugu rubripes muscle. pcDNA-3.1-CP can be detected in gills, muscle and head kidney, and lasted for more than 70 d post-injection. The transcripts of IgM and interferon inducible gene Mx were up-regulated after being immunized in different tissues, and immune factors, such as IFN-γ and C3, were also up-regulated in serum, while C4 was down-regulated one week after injection. It was suggested that pcDNA-3.1-CP can be a potential DNA vaccine in stimulating the immune system of T. rubripes; however, NNV challenge needs to be conducted in the following experiments.
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Affiliation(s)
- Mingguang Mao
- Yazhou Bay Innovation Institute, Hainan Tropical Ocean University, Sanya 572022, China
- Key Laboratory of Utilization and Conservation for Tropical Marine Bioresources, Ministry of Education, Hainan Tropical Ocean University, Sanya 572022, China
| | - Jielan Jiang
- Yazhou Bay Innovation Institute, Hainan Tropical Ocean University, Sanya 572022, China
- Key Laboratory of Utilization and Conservation for Tropical Marine Bioresources, Ministry of Education, Hainan Tropical Ocean University, Sanya 572022, China
| | - Jia Xu
- College of Fisheries and Life Sciences, Dalian Ocean University, Dalian 116023, China
| | - Yumeng Liu
- College of Fisheries and Life Sciences, Dalian Ocean University, Dalian 116023, China
| | - Haishan Wang
- Yazhou Bay Innovation Institute, Hainan Tropical Ocean University, Sanya 572022, China
- Key Laboratory of Utilization and Conservation for Tropical Marine Bioresources, Ministry of Education, Hainan Tropical Ocean University, Sanya 572022, China
| | - Yunxiang Mao
- Yazhou Bay Innovation Institute, Hainan Tropical Ocean University, Sanya 572022, China
- Key Laboratory of Utilization and Conservation for Tropical Marine Bioresources, Ministry of Education, Hainan Tropical Ocean University, Sanya 572022, China
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Moreno P, Leiva-Rebollo R, Garcia-Rosado E, Bejar J, Alonso MC. Cytokine-like activity of European sea bass ISG15 protein on RGNNV-infected E-11 cells. FISH & SHELLFISH IMMUNOLOGY 2022; 128:612-619. [PMID: 36007830 DOI: 10.1016/j.fsi.2022.08.048] [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: 01/18/2022] [Revised: 07/25/2022] [Accepted: 08/18/2022] [Indexed: 06/15/2023]
Abstract
IFN-I generates an antiviral state by inducing the expression of numerous genes, called IFN-stimulated genes, ISGs, including ISG15, which is the only ISG with cytokine-like activity. In a previous study, we developed the Dl_ISG15_E11 cell line, which consisted of E11 cells able to express and secrete sea bass ISG15. The current study is a step forward, analysing the effect of secreted sea bass ISG15 on RGNNV replication in E11 cells, and looking into its immunomodulatory activity in order to corroborate its cytokine-like activity. The medium from ISG15-produccing cells compromised RGNNV replication, as it has been demonstrated both, by reduction in the viral genome synthesis and, specially, in the yield of infective viral particles. The implication of sea bass ISG15 in this protection has been demonstrated by ISG15 removal, which decreased the percentage of surviving cells upon viral infection, and by incubation of RGNNV-infected cells with a recombinant sea bass ISG15 protein, which resulted in almost full protection. Furthermore, the immunomodulatory activity of extracellular sea bass ISG15 has been demonstrated, which reaffirms a cytokine-like role for this protein.
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Affiliation(s)
- Patricia Moreno
- Universidad de Málaga, Instituto de Biotecnología y Desarrollo Azul, IBYDA, Departamento de Microbiología, Facultad de Ciencias, 29071, Málaga, Spain
| | - Rocio Leiva-Rebollo
- Universidad de Málaga, Instituto de Biotecnología y Desarrollo Azul, IBYDA, Departamento de Microbiología, Facultad de Ciencias, 29071, Málaga, Spain
| | - Esther Garcia-Rosado
- Universidad de Málaga, Instituto de Biotecnología y Desarrollo Azul, IBYDA, Departamento de Microbiología, Facultad de Ciencias, 29071, Málaga, Spain
| | - Julia Bejar
- Universidad de Málaga, Instituto de Biotecnología y Desarrollo Azul, IBYDA, Departamento de Biología Celular, Genética y Fisiología, Facultad de Ciencias, 29071, Málaga, Spain
| | - M Carmen Alonso
- Universidad de Málaga, Instituto de Biotecnología y Desarrollo Azul, IBYDA, Departamento de Microbiología, Facultad de Ciencias, 29071, Málaga, Spain.
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5
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Errani F, Volpe E, Riera-Ferrer E, Caffara M, Padrós F, Gustinelli A, Fioravanti M, Ciulli S. Development and diagnostic validation of a one-step multiplex RT-PCR assay as a rapid method to detect and identify Nervous Necrosis Virus (NNV) and its variants circulating in the Mediterranean. PLoS One 2022; 17:e0273802. [PMID: 36018889 PMCID: PMC9417010 DOI: 10.1371/journal.pone.0273802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Accepted: 08/15/2022] [Indexed: 11/18/2022] Open
Abstract
Nervous Necrosis Virus (NNV) represents one of the most threatening pathogens for Mediterranean aquaculture. Several NNV strains are currently co-circulating in the Mediterranean Basin with a high prevalence of the RGNNV genotype and the RGNNV/SJNNV reassortant strain and a more limited diffusion of the SJNNV genotype and the SJNNV/RGNNV reassortant. In the present study, a one-step multiplex RT-PCR (mRT-PCR) assay was developed as an easy, cost-effective and rapid diagnostic technique to detect RGNNV and the reassortant RGNNV/SJNNV strain and to distinguish them from SJNNV and the reassortant SJNNV/RGNNV strain in a single RT-PCR reaction. A unique amplification profile was obtained for each genotype/reassortant enabling their rapid identification from cell culture lysates or directly from brain tissues of suspected fish. The method’s detection limit varied between 102.3 and 103.4 TCID50 ml-1 depending on viral strains. No cross-reacitivty with viruses and bacteria frequently associated with gilthead seabream, European seabass and marine environment was observed. The mRT-PCR was shown to be an accurate, rapid and affordable method to support traditional diagnostic techniques in the diagnosis of VNN, being able to reduce considerably the time to identify the viral genotype or the involvement of reassortant strains.
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Affiliation(s)
- Francesca Errani
- Department of Veterinary Medical Sciences, Alma Mater Studiorum, University of Bologna, Cesenatico (FC), Italy
| | - Enrico Volpe
- Department of Veterinary Medical Sciences, Alma Mater Studiorum, University of Bologna, Cesenatico (FC), Italy
| | | | - Monica Caffara
- Department of Veterinary Medical Sciences, Alma Mater Studiorum, University of Bologna, Ozzano dell’Emilia (BO), Italy
| | - Francesc Padrós
- Facultat de Veterinària, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Andrea Gustinelli
- Department of Veterinary Medical Sciences, Alma Mater Studiorum, University of Bologna, Ozzano dell’Emilia (BO), Italy
| | - Marialetizia Fioravanti
- Department of Veterinary Medical Sciences, Alma Mater Studiorum, University of Bologna, Ozzano dell’Emilia (BO), Italy
| | - Sara Ciulli
- Department of Veterinary Medical Sciences, Alma Mater Studiorum, University of Bologna, Cesenatico (FC), Italy
- * E-mail:
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Vázquez-Salgado L, Pascoli F, Marsella A, Biasini L, Buratin A, Pretto T, Abbadi M, Melchiotti E, Bandín I, Toffan A. Role of Rotifers in Betanodavirus Transmission to European Sea Bass Larvae. Front Vet Sci 2022; 9:932327. [PMID: 35990261 PMCID: PMC9383259 DOI: 10.3389/fvets.2022.932327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 06/09/2022] [Indexed: 11/13/2022] Open
Abstract
Marine invertebrates such as rotifers or Artemia, frequently used for fish larvae feeding, can be a potential source of pathogens. It has been demonstrated that Artemia can act as a nervous necrosis virus (NNV)-vector to Senegalese sole larvae. Therefore, in this study, we aimed to clarify the role of rotifers in NNV transmission to sea bass larvae following an oral challenge. Our results showed that sea bass larvae fed on a single dose of rotifers retaining NNV displayed clinical signs, mortality, and viral replication similar to the immersion challenge, although the course of the infection was slightly different between the two infection routes. Furthermore, we also demonstrated that rotifers can internalize NNV particles due to their filtering nature and maintain virus viability since viral particles were detected by immunohistochemistry, immunofluorescence, and cell culture within the rotifer body. However, viral quantification data suggested that rotifers are not permissive to NNV replication. In conclusion, this research demonstrated NNV horizontal transmission through rotifers to sea bass larvae, highlighting the importance of establishing strict routine controls on live food to prevent the introduction of potential pathogens to hatcheries.
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Affiliation(s)
- Lucia Vázquez-Salgado
- Departamento de Microbiología y Parasitología, Instituto de Acuicultura, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Francesco Pascoli
- Istituto Zooprofilattico Sperimentale delle Venezie, OIE Reference Laboratory for Viral Encephalo-Retinopathy, National Reference Laboratory for Fish Diseases Legnaro, Padova, Italy
| | - Andrea Marsella
- Istituto Zooprofilattico Sperimentale delle Venezie, OIE Reference Laboratory for Viral Encephalo-Retinopathy, National Reference Laboratory for Fish Diseases Legnaro, Padova, Italy
| | - Lorena Biasini
- Istituto Zooprofilattico Sperimentale delle Venezie, OIE Reference Laboratory for Viral Encephalo-Retinopathy, National Reference Laboratory for Fish Diseases Legnaro, Padova, Italy
| | - Alessandra Buratin
- Istituto Zooprofilattico Sperimentale delle Venezie, OIE Reference Laboratory for Viral Encephalo-Retinopathy, National Reference Laboratory for Fish Diseases Legnaro, Padova, Italy
| | - Tobia Pretto
- Istituto Zooprofilattico Sperimentale delle Venezie, OIE Reference Laboratory for Viral Encephalo-Retinopathy, National Reference Laboratory for Fish Diseases Legnaro, Padova, Italy
| | - Miriam Abbadi
- Istituto Zooprofilattico Sperimentale delle Venezie, OIE Reference Laboratory for Viral Encephalo-Retinopathy, National Reference Laboratory for Fish Diseases Legnaro, Padova, Italy
| | - Erica Melchiotti
- Department of Histopathology, Istituto Zooprofilattico Sperimentale delle Venezie Legnaro, Padova, Italy
| | - Isabel Bandín
- Departamento de Microbiología y Parasitología, Instituto de Acuicultura, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Anna Toffan
- Istituto Zooprofilattico Sperimentale delle Venezie, OIE Reference Laboratory for Viral Encephalo-Retinopathy, National Reference Laboratory for Fish Diseases Legnaro, Padova, Italy
- *Correspondence: Anna Toffan
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Comprehensive Linear Epitope Prediction System for Host Specificity in Nodaviridae. Viruses 2022; 14:v14071357. [PMID: 35891339 PMCID: PMC9319239 DOI: 10.3390/v14071357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 06/15/2022] [Accepted: 06/20/2022] [Indexed: 02/01/2023] Open
Abstract
Background: Nodaviridae infection is one of the leading causes of death in commercial fish. Although many vaccines against this virus family have been developed, their efficacies are relatively low. Nodaviridae are categorized into three subfamilies: alphanodavirus (infects insects), betanodavirus (infects fish), and gammanodavirus (infects prawns). These three subfamilies possess host-specific characteristics that could be used to identify effective linear epitopes (LEs). Methodology: A multi-expert system using five existing LE prediction servers was established to obtain initial LE candidates. Based on the different clustered pathogen groups, both conserved and exclusive LEs among the Nodaviridae family could be identified. The advantages of undocumented cross infection among the different host species for the Nodaviridae family were applied to re-evaluate the impact of LE prediction. The surface structural characteristics of the identified conserved and unique LEs were confirmed through 3D structural analysis, and concepts of surface patches to analyze the spatial characteristics and physicochemical propensities of the predicted segments were proposed. In addition, an intelligent classifier based on the Immune Epitope Database (IEDB) dataset was utilized to review the predicted segments, and enzyme-linked immunosorbent assays (ELISAs) were performed to identify host-specific LEs. Principal findings: We predicted 29 LEs for Nodaviridae. The analysis of the surface patches showed common tendencies regarding shape, curvedness, and PH features for the predicted LEs. Among them, five predicted exclusive LEs for fish species were selected and synthesized, and the corresponding ELISAs for antigenic feature analysis were examined. Conclusion: Five identified LEs possessed antigenicity and host specificity for grouper fish. We demonstrate that the proposed method provides an effective approach for in silico LE prediction prior to vaccine development and is especially powerful for analyzing antigen sequences with exclusive features among clustered antigen groups.
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Pathogenicity of Different Betanodavirus RGNNV/SJNNV Reassortant Strains in European Sea Bass. Pathogens 2022; 11:pathogens11040458. [PMID: 35456134 PMCID: PMC9026442 DOI: 10.3390/pathogens11040458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 03/22/2022] [Accepted: 04/06/2022] [Indexed: 11/21/2022] Open
Abstract
European sea bass (Dicentrarchus labrax) is an important farmed marine species for Mediterranean aquaculture. Outbreaks of betanodavirus represent one of the main infectious threats for this species. The red-spotted grouper nervous necrosis virus genotype (RGNNV) is the most widely spread in Southern Europe, while the striped jack nervous necrosis virus genotype (SJNNV) has been rarely detected. The existence of natural reassortants between these genotypes has been demonstrated, the RGNNV/SJNNV strain being the most common. This study aimed to evaluate the pathogenicity of different RGNNV/SJNNV strains in European sea bass. A selection of nine European reassortants together with parental RGNNV and SJNNV strains were used to perform in vivo experimental challenges via intramuscular injection. Additional in vivo experimental challenges were performed by bath immersion in order to mimic the natural infection route of the virus. Overall, results on survival rates confirmed the susceptibility of European sea bass to reassortants and showed different levels of induced mortalities. Results obtained by RT-qPCR also highlighted high viral loads in asymptomatic survivors, suggesting a possible reservoir role of this species. Our findings on the comparison of complete genomic segments of all reassortants have shed light on different amino acid residues likely involved in the variable pathogenicity of RGNNV/SJNNV strains in European sea bass.
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Padrós F, Caggiano M, Toffan A, Constenla M, Zarza C, Ciulli S. Integrated Management Strategies for Viral Nervous Necrosis (VNN) Disease Control in Marine Fish Farming in the Mediterranean. Pathogens 2022; 11:pathogens11030330. [PMID: 35335654 PMCID: PMC8955002 DOI: 10.3390/pathogens11030330] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 03/01/2022] [Accepted: 03/03/2022] [Indexed: 12/16/2022] Open
Abstract
Viral nervous necrosis (VNN) is the most important viral disease affecting farmed fish in the Mediterranean. VNN can affect multiple fish species in all production phases (broodstock, hatchery, nursery and ongrowing) and sizes, but it is especially severe in larvae and juvenile stages, where can it cause up to 100% mortalities. European sea bass has been and is still the most affected species, and VNN in gilthead sea bream has become an emerging problem in recent years affecting larvae and juveniles and associated to the presence of new nervous necrosis virus (NNV) reassortants. The relevance of this disease as one of the main biological hazards for Mediterranean finfish farming has been particularly addressed in two recent H2020 projects: PerformFISH and MedAID. The presence of the virus in the environment and in the farming systems poses a serious menace for the development of the Mediterranean finfish aquaculture. Several risks associated to the VNN development in farms have been identified in the different phases of the farming system. The main risks concerning VNN affecting gilthead seabream and European seabass have been identified as restocking from wild fish in broodstock facilities, the origin of eggs and juveniles, quality water supply and live food in hatcheries and nurseries, and infected juveniles and location of farms in endemic areas for on-growing sites. Due to the potential severe impact, a holistic integrated management approach is the best strategy to control VNN in marine fish farms. This approach should include continuous surveillance and early and accurate diagnosis, essential for an early intervention when an outbreak occurs, the implementation of biosecurity and disinfection procedures in the production sites and systematic vaccination with effective vaccines. Outbreak management practices, clinical aspects, diagnostic techniques, and disinfections methods are reviewed in detail in this paper. Additionally, new strategies are becoming more relevant, such as the use of genetic resistant lines and boosting the fish immune system though nutrition.
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Affiliation(s)
- Francesc Padrós
- Departament de Biologia Animal, de Biologia Vegetal i d’Ecologia and Servei de Diagnòstic Patològic en Peixos, Universitat Autònoma de Barcelona, 08193 Barcelona, Spain;
- Correspondence:
| | | | - Anna Toffan
- National Reference Laboratory for Fish Diseases, OIE Reference Laboratory for Viral Encephalopathy and Retinopathy, Istituto Zooprofilattico Sperimentale delle Venezie, 35020 Legnaro (PD), Italy;
| | - Maria Constenla
- Departament de Biologia Animal, de Biologia Vegetal i d’Ecologia and Servei de Diagnòstic Patològic en Peixos, Universitat Autònoma de Barcelona, 08193 Barcelona, Spain;
| | - Carlos Zarza
- Health Department, Skretting Aquaculture Research Centre, P.O. Box 48, 4001 Stavanger, Norway;
| | - Sara Ciulli
- Department of Veterinary Medical Sciences DIMEVET, Alma Mater Studiorum University of Bologna, 47042 Cesenatico (FC), Italy;
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10
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Falco A, Bello-Perez M, Díaz-Puertas R, Mold M, Adamek M. Update on the Inactivation Procedures for the Vaccine Development Prospects of a New Highly Virulent RGNNV Isolate. Vaccines (Basel) 2021; 9:vaccines9121441. [PMID: 34960187 PMCID: PMC8705346 DOI: 10.3390/vaccines9121441] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 11/30/2021] [Accepted: 12/03/2021] [Indexed: 01/01/2023] Open
Abstract
Viral nervous necrosis (VNN) caused by the nervous necrosis virus (NNV) affects a broad range of primarily marine fish species, with mass mortality rates often seen among larvae and juveniles. Its genetic diversification may hinder the effective implementation of preventive measures such as vaccines. The present study describes different inactivation procedures for developing an inactivated vaccine against a new NNV isolate confirmed to possess deadly effects upon the European seabass (Dicentrarchus labrax), an important Mediterranean farmed fish species that is highly susceptible to this disease. First, an NNV isolate from seabass adults diagnosed with VNN was rescued and the sequences of its two genome segments (RNA1 and RNA2) were classified into the red-spotted grouper NNV (RGNNV) genotype, closely clustering to the highly pathogenic 283.2009 isolate. The testing of different inactivation procedures revealed that the virus particles of this isolate showed a marked resistance to heat (for at least 60 °C for 120 min with and without 1% BSA) but that they were fully inactivated by 3 mJ/cm2 UV-C irradiation and 24 h 0.2% formalin treatment, which stood out as promising NNV-inactivation procedures for potential vaccine candidates. Therefore, these procedures are feasible, effective, and rapid response strategies for VNN control in aquaculture.
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Affiliation(s)
- Alberto Falco
- Institute of Research, Development and Innovation in Healthcare Biotechnology in Elche (IDiBE), Miguel Hernández University, 03202 Elche, Spain; (M.B.-P.); (R.D.-P.)
- Correspondence:
| | - Melissa Bello-Perez
- Institute of Research, Development and Innovation in Healthcare Biotechnology in Elche (IDiBE), Miguel Hernández University, 03202 Elche, Spain; (M.B.-P.); (R.D.-P.)
| | - Rocío Díaz-Puertas
- Institute of Research, Development and Innovation in Healthcare Biotechnology in Elche (IDiBE), Miguel Hernández University, 03202 Elche, Spain; (M.B.-P.); (R.D.-P.)
| | - Matthew Mold
- The Birchall Centre, Lennard-Jones Laboratories, Keele University, Staffordshire ST5 5BG, UK;
| | - Mikolaj Adamek
- Fish Disease Research Unit, Institute for Parasitology, University of Veterinary Medicine, 30559 Hannover, Germany;
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11
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Nervous Necrosis Virus-like Particle (VLP) Vaccine Stimulates European Sea Bass Innate and Adaptive Immune Responses and Induces Long-Term Protection against Disease. Pathogens 2021; 10:pathogens10111477. [PMID: 34832632 PMCID: PMC8623669 DOI: 10.3390/pathogens10111477] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 11/02/2021] [Accepted: 11/02/2021] [Indexed: 12/29/2022] Open
Abstract
The rapidly increasing Mediterranean aquaculture production of European sea bass is compromised by outbreaks of viral nervous necrosis, which can be recurrent and detrimental. In this study, we evaluated the duration of protection and immune response in sea bass given a single dose of a virus-like particle (VLP)-based vaccine. Examinations included experimental challenge with nervous necrosis virus (NNV), serological assays for NNV-specific antibody reactivity, and immune gene expression analysis. VLP-vaccinated fish showed high and superior survival in challenge both 3 and 7.5 months (1800 and 4500 dd) post-vaccination (RPS 87 and 88, OR (surviving) = 16.5 and 31.5, respectively, p < 0.01). Although not providing sterile immunity, VLP vaccination seemed to control the viral infection, as indicated by low prevalence of virus in the VLP-vaccinated survivors. High titers of neutralizing and specific antibodies were produced in VLP-vaccinated fish and persisted for at least ~9 months post-vaccination as well as after challenge. However, failure of immune sera to protect recipient fish in a passive immunization trial suggested that other immune mechanisms were important for protection. Accordingly, gene expression analysis revealed that VLP-vaccination induced a mechanistically broad immune response including upregulation of both innate and adaptive humoral and cellular components (mx, isg12, mhc I, mhc II, igm, and igt). No clinical side effects of the VLP vaccination at either tissue or performance levels were observed. The results altogether suggested the VLP-based vaccine to be suitable for clinical testing under farming conditions.
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12
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Investigation of betanodavirus in sea bass (Dicentrarchus labrax) at all production stages in all hatcheries and on selected farms in Turkey. Arch Virol 2021; 166:3343-3356. [PMID: 34604927 DOI: 10.1007/s00705-021-05254-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 08/12/2021] [Indexed: 10/20/2022]
Abstract
Viral nervous necrosis (VNN) is one of the most important problems in sea bass culture. Although there have been many studies on detection and molecular characterization of betanodavirus, the causative agent of VNN, there has been little focus on understanding its prevalence to create epidemiological maps. The purpose of this study was to investigate the prevalence of betanodavirus in active sea bass hatcheries and on selected farms in Turkey by RT-qPCR. A total of 2460 samples, including fertilized eggs, prelarvae, postlarvae, fry, and fingerlings, were collected from 16 hatcheries to cover all production stages. A total of 600 sea bass were also collected from 20 farms. Betanodavirus was detected in one hatchery (1/16) in fingerling-sized sea bass, and the prevalence of betanodavirus at the hatchery level was calculated to be 6.25%. Betanodavirus was also detected on one farm (1/20) in fingerling-sized sea bass, and the prevalence of betanodavirus at the farm level was calculated to be 5%. Virus isolation initially could not be achieved in E-11 cells, but later, SSN-1 cells were used successfully. Partial genome sequence analysis of the RNA1 and RNA2 segments of the viruses revealed that they were of the red-spotted grouper nervous necrosis virus genotype, which is endemic in the Mediterranean basin. The absence of mortality related to VNN in the hatcheries and on the farms, the healthy appearance of the sea bass, the low viral load detected, and the results of retrospective epidemiological studies indicated that the infection was subclinical. Not detecting betanodavirus in other age groups where biosecurity was implemented indicates that there was no active infection. In light of these findings, it can be concluded that there was no betanodavirus circulating in hatcheries, and the virus might have been of seawater origin.
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13
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Chérif N, El Jeni R, Amdouni F, Zreilli S, Djabou H, Khemiri S, Tliba I, Bouhaouala-Zahar B, Maatoug K, Zaafran S, Groman D. Phylogeography of betanodavirus genotypes circulating in Tunisian aquaculture sites, 2012-2019. DISEASES OF AQUATIC ORGANISMS 2021; 146:53-63. [PMID: 34553693 DOI: 10.3354/dao03614] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The purpose of this study was to determine the phylogenetic relationships among the primary betanodavirus strains circulating in Tunisian coastal waters. A survey was conducted to investigate nodavirus infections at 15 European sea bass Dicentrarchus labrax and gilthead sea bream Sparus aurata farming sites located along the northern and eastern coasts of Tunisia. The primary objective of the study was to create epidemiological awareness of these infections by determining phylogenetic relationships between the main betanodavirus strains circulating during the period 2012-2019, using RNA1 and/or RNA2 genome segments. Approximately 40% (118 of 294) tissue pools tested were positive for betanodavirus. Positive pools were distributed across all of the sampling sites. While fish mortalities were always correlated with the presence of virus in sea bass, a severe outbreak was also identified in sea bream larvae in 2019. Phylogenetic analysis revealed that almost all Tunisian strains from both sea bass and sea bream irrespective of outbreaks clustered within the RGNNV genotype. It is noteworthy that samples collected during the 2019 outbreak from sea bream contained both RNA1 and RNA2 fragments belonging to the RGNNV and SJNNV genotype, respectively, an indication of viral genome reassortment. To our knowledge, this is the first report of reassortant betanodavirus in Tunisia.
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Affiliation(s)
- Nadia Chérif
- Aquaculture Laboratory, National Institute of Marine Sciences and Technologies, 2025 Salammbô, Tunisia
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14
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Barsøe S, Toffan A, Pascoli F, Stratmann A, Pretto T, Marsella A, Er-Rafik M, Vendramin N, Olesen NJ, Sepúlveda D, Lorenzen N. Long-Term Protection and Serologic Response of European Sea Bass Vaccinated with a Betanodavirus Virus-Like Particle Produced in Pichia pastoris. Vaccines (Basel) 2021; 9:vaccines9050447. [PMID: 34063318 PMCID: PMC8147411 DOI: 10.3390/vaccines9050447] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 04/22/2021] [Accepted: 04/23/2021] [Indexed: 01/10/2023] Open
Abstract
Viral Nervous Necrosis (VNN) causes high mortality and reduced growth in farmed European sea bass (Dicentrarchus labrax) in the Mediterranean. In the current studies, we tested a novel Pichia-produced virus-like particle (VLP) vaccine against VNN in European sea bass, caused by the betanodavirus “Red-Spotted Grouper Nervous Necrosis Virus” (RGNNV). European sea bass were immunized with a VLP-based vaccine formulated with different concentrations of antigen and with or without adjuvant. Antibody response was evaluated by ELISA and serum neutralization. The efficacy of these VLP-vaccine formulations was evaluated by an intramuscular challenge with RGNNV at different time points (1, 2 and 10 months post-vaccination) and both dead and surviving fish were sampled to evaluate the level of viable virus in the brain. The VLP-based vaccines induced an effective protective immunity against experimental infection at 2 months post-vaccination, and even to some degree at 10 months post-vaccination. Furthermore, the vaccine formulations triggered a dose-dependent response in neutralizing antibodies. Serologic response and clinical efficacy, measured as relative percent survival (RPS), seem to be correlated with the administered dose, although for the individual fish, a high titer of neutralizing antibodies prior to challenge was not always enough to protect against disease. The efficacy of the VLP vaccine could not be improved by formulation with a water-in-oil (W/O) adjuvant. The developed RGNNV-VLPs show a promising effect as a vaccine candidate, even without adjuvant, to protect sea bass against disease caused by RGNNV. However, detection of virus in vaccinated survivors means that it cannot be ruled out that survivors can transmit the virus.
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Affiliation(s)
- Sofie Barsøe
- National Institute of Aquatic Resources (DTU AQUA), Technical University of Denmark, 2800 Lyngby, Denmark; (S.B.); (N.V.); (N.J.O.); (D.S.)
| | - Anna Toffan
- Istituto Zooprofilattico Sperimentale delle Venezie (IZSVe), 35020 Legnaro, Padua, Italy; (A.T.); (F.P.); (T.P.); (A.M.)
| | - Francesco Pascoli
- Istituto Zooprofilattico Sperimentale delle Venezie (IZSVe), 35020 Legnaro, Padua, Italy; (A.T.); (F.P.); (T.P.); (A.M.)
| | | | - Tobia Pretto
- Istituto Zooprofilattico Sperimentale delle Venezie (IZSVe), 35020 Legnaro, Padua, Italy; (A.T.); (F.P.); (T.P.); (A.M.)
| | - Andrea Marsella
- Istituto Zooprofilattico Sperimentale delle Venezie (IZSVe), 35020 Legnaro, Padua, Italy; (A.T.); (F.P.); (T.P.); (A.M.)
| | - Mériem Er-Rafik
- National Center for Nano Fabrication and Characterization (DTU Nanolab), Technical University of Denmark, 2800 Lyngby, Denmark;
| | - Niccolò Vendramin
- National Institute of Aquatic Resources (DTU AQUA), Technical University of Denmark, 2800 Lyngby, Denmark; (S.B.); (N.V.); (N.J.O.); (D.S.)
| | - Niels J. Olesen
- National Institute of Aquatic Resources (DTU AQUA), Technical University of Denmark, 2800 Lyngby, Denmark; (S.B.); (N.V.); (N.J.O.); (D.S.)
| | - Dagoberto Sepúlveda
- National Institute of Aquatic Resources (DTU AQUA), Technical University of Denmark, 2800 Lyngby, Denmark; (S.B.); (N.V.); (N.J.O.); (D.S.)
| | - Niels Lorenzen
- National Institute of Aquatic Resources (DTU AQUA), Technical University of Denmark, 2800 Lyngby, Denmark; (S.B.); (N.V.); (N.J.O.); (D.S.)
- Correspondence:
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15
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Faggion S, Bertotto D, Babbucci M, Dalla Rovere G, Franch R, Bovolenta M, Laureau S, Pascoli F, Toffan A, Bargelloni L, Carnier P. Resistance to viral nervous necrosis in European sea bass (Dicentrarchus labrax L.): heritability and relationships with body weight, cortisol concentration, and antibody titer. Genet Sel Evol 2021; 53:32. [PMID: 33794770 PMCID: PMC8017662 DOI: 10.1186/s12711-021-00625-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 03/23/2021] [Indexed: 11/25/2022] Open
Abstract
Background Susceptibility of European sea bass (Dicentrarchus labrax L.) to viral nervous necrosis (VNN) is well-known. Interest towards selective breeding as a tool to enhance genetic resistance in this species has increased sharply due to the major threat represented by VNN for farmed sea bass and limitations concerning specific therapeutical measures. A sea bass experimental population (N = 650) was challenged with nervous necrosis virus (NNV) to investigate genetic variation in VNN mortality. In addition, relationships of this trait with serum cortisol concentration after stress exposure, antibody titer against NNV antigens, and body weight at a fixed age were studied to identify potential indicator traits of VNN resistance. Results The estimate of heritability for VNN mortality was moderate and ranged from 0.15 (HPD95%, 95% highest posterior density interval: 0.02, 0.31) to 0.23 (HPD95%: 0.06, 0.47). Heritability estimates for cortisol concentration, antibody titer, and body weight were 0.19 (HPD95%: 0.07, 0.34), 0.36 (HPD95%: 0.16, 0.59) and 0.57 (HPD95%: 0.33, 0.84), respectively. Phenotypic relationships between traits were trivial and not statistically significant, except for the estimated correlation between antibody titer and body weight (0.24). Genetic correlations of mortality with body weight or antibody titer (− 0.39) exhibited a 0.89 probability of being negative. A negligible genetic correlation between mortality and cortisol concentration was detected. Antibody titer was estimated to be positively correlated with body weight (0.49). Conclusions Antibody titer against NNV offers the opportunity to use indirect selection to enhance resistance, while the use of cortisol concentration as an indicator trait in breeding programs for VNN resistance is questionable. The estimate of heritability for VNN mortality indicates the feasibility of selective breeding to enhance resistance to NNV and raises attention to the development of genomic prediction tools to simplify testing procedures for selection candidates.
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Affiliation(s)
- Sara Faggion
- Department of Comparative Biomedicine and Food Science (BCA), University of Padova, Legnaro, PD, Italy
| | - Daniela Bertotto
- Department of Comparative Biomedicine and Food Science (BCA), University of Padova, Legnaro, PD, Italy.
| | - Massimiliano Babbucci
- Department of Comparative Biomedicine and Food Science (BCA), University of Padova, Legnaro, PD, Italy
| | - Giulia Dalla Rovere
- Department of Comparative Biomedicine and Food Science (BCA), University of Padova, Legnaro, PD, Italy
| | - Rafaella Franch
- Department of Comparative Biomedicine and Food Science (BCA), University of Padova, Legnaro, PD, Italy
| | | | | | - Francesco Pascoli
- Istituto Zooprofilattico Sperimentale Delle Venezie, National Reference Laboratory (NRL) for Diseases of Fish, Mollusk and Crustacean, Legnaro, PD, Italy
| | - Anna Toffan
- Istituto Zooprofilattico Sperimentale Delle Venezie, National Reference Laboratory (NRL) for Diseases of Fish, Mollusk and Crustacean, Legnaro, PD, Italy
| | - Luca Bargelloni
- Department of Comparative Biomedicine and Food Science (BCA), University of Padova, Legnaro, PD, Italy
| | - Paolo Carnier
- Department of Comparative Biomedicine and Food Science (BCA), University of Padova, Legnaro, PD, Italy
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16
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Moreno P, Gemez-Mata J, Garcia-Rosado E, Bejar J, Labella AM, Souto S, Alonso MC. Differential immunogene expression profile of European sea bass (Dicentrarchus labrax, L.) in response to highly and low virulent NNV. FISH & SHELLFISH IMMUNOLOGY 2020; 106:56-70. [PMID: 32702480 DOI: 10.1016/j.fsi.2020.06.052] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 06/25/2020] [Accepted: 06/26/2020] [Indexed: 06/11/2023]
Abstract
European sea bass is highly susceptible to the nervous necrosis virus, RGNNV genotype, whereas natural outbreaks caused by the SJNNV genotype have not been recorded. The onset and severity of an infectious disease depend on pathogen virulence factors and the host immune response. The importance of RGNNV capsid protein amino acids 247 and 270 as virulence factors has been previously demonstrated in European sea bass; however, sea bass immune response against nodaviruses with different levels of virulence has been poorly characterized. Knowing the differences between the immune response against both kinds of isolates may be key to get more insight into the host mechanisms responsible for NNV virulence. For this reason, this study analyses the transcription of immunogenes differentially expressed in European sea bass inoculated with nodaviruses with different virulence: a RGNNV virus obtained by reverse genetics (rDl956), highly virulent to sea bass, and a mutated virus (Mut247+270Dl956, RGNNV virus displaying SJNNV-type amino acids at positions 247 and 270 of the capsid protein), presenting lower virulence. This study has been performed in brain and head kidney, and the main differences between the immunogene responses triggered by both viruses have been observed in brain. The immunogene response in this organ is stronger after inoculation with the most virulent virus, and the main differences involved genes related with IFN I system, inflammatory response, cell-mediated response, and apoptosis. The lower virulence of Mut247+270Dl956 to European sea bass can be associated with a delayed IFN I response, as well as an early and transitory inflammation and cell-mediated responses, suggesting that those can be pivotal elements in controlling the viral infection, and therefore, their functional activity could be analysed in future studies. In addition, this study supports the role of capsid amino acids at positions 247 and 270 as important determinants of RGNNV virulence to European sea bass.
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Affiliation(s)
- Patricia Moreno
- Universidad de Málaga, Instituto de Biotecnología y Desarrollo Azul, IBYDA, Departamento de Microbiología, Facultad de Ciencias, 29071, Málaga, Spain
| | - Juan Gemez-Mata
- Universidad de Málaga, Instituto de Biotecnología y Desarrollo Azul, IBYDA, Departamento de Microbiología, Facultad de Ciencias, 29071, Málaga, Spain
| | - Esther Garcia-Rosado
- Universidad de Málaga, Instituto de Biotecnología y Desarrollo Azul, IBYDA, Departamento de Microbiología, Facultad de Ciencias, 29071, Málaga, Spain
| | - Julia Bejar
- Universidad de Málaga, Instituto de Biotecnología y Desarrollo Azul, IBYDA, Departamento de Biología Celular, Genética y Fisiología, Facultad de Ciencias, 29071, Málaga, Spain
| | - Alejandro M Labella
- Universidad de Málaga, Instituto de Biotecnología y Desarrollo Azul, IBYDA, Departamento de Microbiología, Facultad de Ciencias, 29071, Málaga, Spain
| | - Sandra Souto
- Departamento de Microbiología y Parasitología, Instituto de Acuicultura, Universidad de Santiago de Compostela, Santiago de Compostela, Spain
| | - M Carmen Alonso
- Universidad de Málaga, Instituto de Biotecnología y Desarrollo Azul, IBYDA, Departamento de Microbiología, Facultad de Ciencias, 29071, Málaga, Spain.
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17
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Betanodavirus and VER Disease: A 30-year Research Review. Pathogens 2020; 9:pathogens9020106. [PMID: 32050492 PMCID: PMC7168202 DOI: 10.3390/pathogens9020106] [Citation(s) in RCA: 116] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 01/22/2020] [Accepted: 02/04/2020] [Indexed: 12/18/2022] Open
Abstract
The outbreaks of viral encephalopathy and retinopathy (VER), caused by nervous necrosis virus (NNV), represent one of the main infectious threats for marine aquaculture worldwide. Since the first description of the disease at the end of the 1980s, a considerable amount of research has gone into understanding the mechanisms involved in fish infection, developing reliable diagnostic methods, and control measures, and several comprehensive reviews have been published to date. This review focuses on host–virus interaction and epidemiological aspects, comprising viral distribution and transmission as well as the continuously increasing host range (177 susceptible marine species and epizootic outbreaks reported in 62 of them), with special emphasis on genotypes and the effect of global warming on NNV infection, but also including the latest findings in the NNV life cycle and virulence as well as diagnostic methods and VER disease control.
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18
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Vijayakumar P, Mani R, Raja S, Dhas TS. Susceptibility of betanodavirus in a newly established vertebra-derived cell line from Mosquitofish (Gambusia affinis). JOURNAL OF FISH DISEASES 2020; 43:263-273. [PMID: 31845349 DOI: 10.1111/jfd.13127] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2019] [Revised: 10/25/2019] [Accepted: 10/25/2019] [Indexed: 06/10/2023]
Abstract
In the present study, a new cell line from the vertebra of mosquitofish Gambusia affinis was successfully established and characterized. The cell line is named as bone Gambusia affinis (BGA) and subcultured for more than 55 passages in Leibovitz's/L15 medium supplemented with 15% FBS at 28°C. The cell line has a modal chromosome number of 48. Molecular characterization of the partial sequence of the coi gene confirmed the origin of the BGA cell line from mosquitofish. These cells exhibited epithelial morphology confirmed by the cytokeratin marker. The BGA cells showed mineralization of their extracellular matrix when stained with alizarin red and von Kossa stain. BGA cells were found to be susceptible to RGNNV and SJNNV strains of betanodavirus (NNV) showing cytopathic effect with multiple vacuolations in the cells. The RT-PCR confirmed the betanodavirus infections in BGA cells. The SEM micrograph showed the morphological changes observed in the cell during virus infection. The in vivo challenge experiment also showed the viral replicating efficiency in the Gambusia affinis with increasing viral titre. Thus, our present results show that the BGA cell line is a useful tool for isolating betanodavirus and could be used to investigate bone cell differentiation and extracellular matrix mineralization.
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Affiliation(s)
- Parameswaran Vijayakumar
- Centre for Ocean Research, Col. Dr Jeppiaar Research Park, Sathyabama Institute of Science and Technology, Chennai, India
| | - Ravi Mani
- Centre for Ocean Research, Col. Dr Jeppiaar Research Park, Sathyabama Institute of Science and Technology, Chennai, India
| | - Sudhakaran Raja
- Aquaculture Biotechnology Laboratory, Vellore Institute of Technology, School of BioSciences and Technology, Vellore, India
| | - Tharmathass Stalin Dhas
- Centre for Ocean Research, Col. Dr Jeppiaar Research Park, Sathyabama Institute of Science and Technology, Chennai, India
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19
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Toffan A, De Salvador M, Scholz F, Pretto T, Buratin A, Rodger HD, Toson M, Cuenca A, Vendramin N. Lumpfish (Cyclopterus lumpus, Linnaeus) is susceptible to viral nervous necrosis: Result of an experimental infection with different genotypes of Betanodavirus. JOURNAL OF FISH DISEASES 2019; 42:1667-1676. [PMID: 31612537 DOI: 10.1111/jfd.13088] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 08/23/2019] [Accepted: 08/26/2019] [Indexed: 06/10/2023]
Abstract
In recent years, the use of cleaner fish for biological control of sea lice has increased considerably. Along with this, a number of infectious diseases have emerged. The aim of this study was to investigate the susceptibility of lumpfish (Cyclopterus lumpus) to Betanodavirus since it was detected in asymptomatic wild wrasses in Norway and Sweden. Three betanodaviruses were used to challenge lumpfish: one RGNNV genotype and two BFNNV genotypes. Fish were injected and monitored for 4 weeks. Brain samples from clinically affected specimens, from weekly randomly selected fish and survivors were subjected to molecular testing, viral isolation, histopathology and immunohistochemistry. Reduced survival was observed but was attributed to tail-biting behaviour, since no nervous signs were observed throughout the study. Betanodavirus RNA was detected in all samples, additionally suggesting an active replication of the virus in the brain. Viral isolation confirmed molecular biology results and revealed a high viral titre in BFNNV-infected groups associated with typical lesions in brains and eyes of survivor fish. We concluded that lumpfish are susceptible to Betanodavirus, as proven by the high viral titre and brain lesions detected, but further studies are necessary to understand if Betanodavirus can cause clinical disease in this species.
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Affiliation(s)
- Anna Toffan
- Istituto Zooprofilattico Sperimentale delle Venezie (IZSVe), Legnaro, Padua, Italy
| | | | - Felix Scholz
- FishVet Group Ireland, Oranmore, Galway, Ireland
| | - Tobia Pretto
- Istituto Zooprofilattico Sperimentale delle Venezie (IZSVe), Legnaro, Padua, Italy
| | - Alessandra Buratin
- Istituto Zooprofilattico Sperimentale delle Venezie (IZSVe), Legnaro, Padua, Italy
| | | | - Marica Toson
- Istituto Zooprofilattico Sperimentale delle Venezie (IZSVe), Legnaro, Padua, Italy
| | - Argelia Cuenca
- National Institute of Aquatic Resources, EURL for fish and crustacean diseases, Technical University of Denmark, Lyngby, Denmark
| | - Niccolò Vendramin
- National Institute of Aquatic Resources, EURL for fish and crustacean diseases, Technical University of Denmark, Lyngby, Denmark
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20
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Capsid amino acids at positions 247 and 270 are involved in the virulence of betanodaviruses to European sea bass. Sci Rep 2019; 9:14068. [PMID: 31575937 PMCID: PMC6773868 DOI: 10.1038/s41598-019-50622-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 08/16/2019] [Indexed: 12/28/2022] Open
Abstract
European sea bass (Dicentrarchus labrax) is severely affected by nervous necrosis disease, caused by nervous necrosis virus (NNV). Two out of the four genotypes of this virus (red-spotted grouper nervous necrosis virus, RGNNV; and striped jack nervous necrosis virus, SJNNV) have been detected in sea bass, although showing different levels of virulence to this fish species. Thus, sea bass is highly susceptible to RGNNV, whereas outbreaks caused by SJNNV have not been reported in this fish species. The role of the capsid protein (Cp) amino acids 247 and 270 in the virulence of a RGNNV isolate to sea bass has been evaluated by the generation of recombinant RGNNV viruses harbouring SJNNV-type amino acids in the above mentioned positions (Mut247Dl965, Mut270Dl965 and Mut247 + 270Dl965). Viral in vitro and in vivo replication, virus virulence and fish immune response triggered by these viruses have been analysed. Mutated viruses replicated on E-11 cells, although showing some differences compared to the wild type virus, suggesting that the mutations can affect the viral cell recognition and entry. In vivo, fish mortality caused by mutated viruses was 75% lower, and viral replication in sea bass brain was altered compared to non-mutated virus. Regarding sea bass immune response, mutated viruses triggered a lower induction of IFN I system and inflammatory response-related genes. Furthermore, mutations caused changes in viral serological properties (especially the mutation in amino acid 270), inducing higher seroconversion and changing antigen recognition.
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21
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Jaramillo D, Fielder S, Whittington RJ, Hick P. Host, agent and environment interactions affecting Nervous necrosis virus infection in Australian bass Macquaria novemaculeata. JOURNAL OF FISH DISEASES 2019; 42:167-180. [PMID: 30488966 DOI: 10.1111/jfd.12913] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 09/24/2018] [Accepted: 09/26/2018] [Indexed: 06/09/2023]
Abstract
Australian bass Macquaria novemaculeata were challenged by immersion with nervous necrosis virus (NNV) at different ages and under controlled conditions to investigate factors affecting disease expression. Fish challenged at 3 weeks of age with 103 TCID50 /ml and higher doses developed clinical disease; a lower dose of 102 TCID50 /ml resulted in incidence below 100% and 101 TCID50 /ml was insufficient to cause infection. Additionally, fish were challenged at 5, 6 and 13 weeks of age at 17 and 21°C to assess the role of the age of the host and water temperature on disease expression. Although Australian bass challenged at all ages had evidence of replication of NNV, only those challenged at 3 weeks of age (20 and 24 days post-hatch [dph]) developed clinical disease. Higher water temperature had an additive effect on disease expression in larvae challenged at 24 dph, but it did not affect the disease outcome in older fish. Finally, isolates of NNV derived from fish with clinical or subclinical disease presentations caused similar cumulative mortality and clinical signs when larvae at 24 dph were challenged, suggesting that agent variation was not responsible for variation in clinical presentation in these field outbreaks of NNV infection.
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Affiliation(s)
- Diana Jaramillo
- Sydney School of Veterinary Science, The University of Sydney, Camden, New South Wales, Australia
| | - Stewart Fielder
- Department of Primary Industries, Port Stephens Fisheries Institute, Port Stephens, New South Wales, Australia
| | - Richard J Whittington
- Sydney School of Veterinary Science, The University of Sydney, Camden, New South Wales, Australia
| | - Paul Hick
- Sydney School of Veterinary Science, The University of Sydney, Camden, New South Wales, Australia
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22
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Pascoli F, Guazzo A, Buratin A, Toson M, Buonocore F, Scapigliati G, Toffan A. Lack of in vivo cross-protection of two different betanodavirus species RGNNV and SJNNV in European sea bass Dicentrachus labrax. FISH & SHELLFISH IMMUNOLOGY 2019; 85:85-89. [PMID: 29056488 DOI: 10.1016/j.fsi.2017.10.033] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 09/20/2017] [Accepted: 10/18/2017] [Indexed: 05/19/2023]
Abstract
Viral encephalopathy and retinopathy (VER) is a severe infective disease characterized by neuropathological changes in several fish species associated with high mortality. The etiological agent is a virus belonging to the Nodaviridae family, genus Betanodavirus. To date, four different betanodavirus species have been officially recognized by International Committee on Taxonomy of Viruses (ICTV), namely the red-spotted grouper- (RGNNV), the striped jack- (SJNNV), the barfin flounder- (BFNNV) and the tiger puffer nervous necrosis virus (TPNNV). Moreover, two reassortants RGNNV/SJNNV and SJNNV/RGNNV have been described. Betanodaviruses can be classified into three different serotypes (A, B and C) that are antigenically different, so none (between serotype A and C) or partial (between serotype B and C) cross-immunoreactivity has been detected in vitro. In this study we investigated the in vivo cross-protection of the two main betanodavirus species (RGNNV and SJNNV), which belong to distinct serotype, by immunizing intraperitoneally (IP) juvenile sea bass with formalin inactivated RGNNV and SJNNV vaccines, followed by a challenge with RGNNV. Fish IP vaccinated with inactivated RGNNV showed a high protection value (85%). Serological analyses highlighted a great specific anti-NNV immunoglobulin M (IgM) production against the homologous virus, while a good seroconversion with low neutralization property was highlighted against the heterologous virus. In fish IP vaccinated with inactivated SJNNV the protection recorded was equal to 25%, significantly lower respect to the one provided by RGNNV IP vaccine. ELISA test detected good IgM production against the homologous virus, and a lower, but still detectable IgM production against the heterologous one. By contrast, serum neutralization test highlighted a poorly detectable antibody production unable to neutralize either the homologous or the heterologous virus. These results confirm that the two serotypes are not cross-protective in vivo. According to these findings, the production of multivalent formulation, or at least the provision of different types of vaccines based on both fish and virus species requirement, should be recommended in order to broaden the range of protection.
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Affiliation(s)
- Francesco Pascoli
- Istituto Zooprofilattico Sperimentale delle Venezie, National Reference Laboratory (NRL) for Diseases of Fish, Mollusk and Crustacean, Legnaro, PD, Italy.
| | - Andrea Guazzo
- Istituto Zooprofilattico Sperimentale delle Venezie, National Reference Laboratory (NRL) for Diseases of Fish, Mollusk and Crustacean, Legnaro, PD, Italy
| | - Alessandra Buratin
- Istituto Zooprofilattico Sperimentale delle Venezie, National Reference Laboratory (NRL) for Diseases of Fish, Mollusk and Crustacean, Legnaro, PD, Italy
| | - Marica Toson
- Istituto Zooprofilattico Sperimentale delle Venezie, Aquatic Animal Epidemiology Laboratory, Legnaro, PD, Italy
| | - Francesco Buonocore
- Department for Innovation in Biological, Agro-food and Forest Systems, University of Tuscia, Viterbo, Italy
| | - Giuseppe Scapigliati
- Department for Innovation in Biological, Agro-food and Forest Systems, University of Tuscia, Viterbo, Italy
| | - Anna Toffan
- Istituto Zooprofilattico Sperimentale delle Venezie, National Reference Laboratory (NRL) for Diseases of Fish, Mollusk and Crustacean, Legnaro, PD, Italy
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23
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Moreno P, Alvarez-Torres D, Garcia-Rosado E, Borrego JJ, Alonso MC. Differential antiviral activity of European sea bass interferon-stimulated 15 protein (ISG15) against RGNNV and SJNNV betanodaviruses. FISH & SHELLFISH IMMUNOLOGY 2018; 83:148-157. [PMID: 30195901 DOI: 10.1016/j.fsi.2018.09.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 09/03/2018] [Accepted: 09/06/2018] [Indexed: 05/07/2023]
Abstract
ISG15 is an antiviral protein acting intracellularly, by conjugation to viral or cellular proteins, or extracellularly, as cytokine. In this work, an in vitro system, consisting of E-11 cells over-expressing European sea bass ISG15 (Dl_ISG15_E11 cells), has been developed to evaluate the European sea bass ISG15 protein activity against RGNNV and SJNNV isolates. Regarding RGNNV, RNA2 copy number and viral titres were similar in E-11 and Dl_ISG15_E11 cells, and the cellular survival analyses demonstrated that Dl_ISG15_E11 cells were not protected from this virus. In contrast, ISG15 compromises SJNNV replication, since a reduction of the SJNNV genome synthesis has been recorded. The ISG15 anti-SJNNV activity was confirmed by viral titration and survival assays. In addition, a role of the intracellular ISG15 in modulating the transcription of endogenous genes has being recorded, with tlr3 gene being knocked out and e3 gene being up-regulated in RGNNV-inoculated Dl_ISG15_E11 cells. Sea bass ISG15 has also been detected extracellularly, and its activity has been evaluated by co-culture. The survival rate of RGNNV-inoculated E-11 cells increased from 25% to 46% when they were co-cultured with ISG15-producing cells. Similarly, the survival rate of SJNNV-inoculated E-11 cells increased from 27% to 51% in co-culture with ISG15-producing cells. To our knowledge, this is the first description of a differential antiviral activity of an ISG15 protein against two betanodavirus species, and the first evaluation of the cytokine-like activity of a fish ISG15 protein on non-immune cells.
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Affiliation(s)
- Patricia Moreno
- Universidad de Málaga, Departamento de Microbiología, Facultad de Ciencias, 29071, Málaga, Spain
| | - Daniel Alvarez-Torres
- Universidad de Málaga, Departamento de Microbiología, Facultad de Ciencias, 29071, Málaga, Spain
| | - Esther Garcia-Rosado
- Universidad de Málaga, Departamento de Microbiología, Facultad de Ciencias, 29071, Málaga, Spain
| | - Juan J Borrego
- Universidad de Málaga, Departamento de Microbiología, Facultad de Ciencias, 29071, Málaga, Spain
| | - M Carmen Alonso
- Universidad de Málaga, Departamento de Microbiología, Facultad de Ciencias, 29071, Málaga, Spain.
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24
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Moreno P, Lopez-Jimena B, Randelli E, Scapigliati G, Buonocore F, Garcia-Rosado E, Borrego JJ, Alonso MC. Immuno-related gene transcription and antibody response in nodavirus (RGNNV and SJNNV)-infected European sea bass (Dicentrarchus labrax L.). FISH & SHELLFISH IMMUNOLOGY 2018; 78:270-278. [PMID: 29702239 DOI: 10.1016/j.fsi.2018.04.054] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 04/19/2018] [Accepted: 04/23/2018] [Indexed: 06/08/2023]
Abstract
The immune response of European sea bass to RGNNV and SJNNV infections has been evaluated by quantifying the transcription of some genes involved in the IFN I system, as well as in the inflammatory and adaptive immune mechanisms. The transcription of IFN-I, ISG-12, ISG-15 and MxA genes has been analyzed in brain and head kidney, showing that RGNNV genotype induces a more intense response of the IFN I system than SJNNV in both organs. In addition, the results obtained indicate the importance of the inflammatory response in nodavirus pathogenesis, with the transcription of IL-8 and TNF-α significantly higher in brain than in head kidney, being RGNNV the strongest inductor. An important difference between the immune response induced by both genotypes refers to the IgM titre in sera, which was higher in SJNNV-inoculated fish. The acquired response is also important locally, since TR-γ transcription is higher in brain than in head kidney (especially in the RGNNV-inoculated group). To our knowledge, this is the first study addressing the sea bass anti-SJNNV immune response.
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Affiliation(s)
- Patricia Moreno
- Universidad de Málaga, Departamento de Microbiología, Facultad de Ciencias, 29071 Málaga, Spain
| | - Benjamin Lopez-Jimena
- Mast Group Ltd., Mast House, Derby Road, Bootle, Merseyside, L20 1EA, England, United Kingdom
| | - Elisa Randelli
- Department for Innovation in Biological, Agrofood and Forest Systems, University of Tuscia, Viterbo, Italy
| | - Giuseppe Scapigliati
- Department for Innovation in Biological, Agrofood and Forest Systems, University of Tuscia, Viterbo, Italy
| | - Francesco Buonocore
- Department for Innovation in Biological, Agrofood and Forest Systems, University of Tuscia, Viterbo, Italy
| | - Esther Garcia-Rosado
- Universidad de Málaga, Departamento de Microbiología, Facultad de Ciencias, 29071 Málaga, Spain
| | - Juan J Borrego
- Universidad de Málaga, Departamento de Microbiología, Facultad de Ciencias, 29071 Málaga, Spain
| | - M Carmen Alonso
- Universidad de Málaga, Departamento de Microbiología, Facultad de Ciencias, 29071 Málaga, Spain.
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25
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Toubanaki DK, Karagouni E. Towards a Dual Lateral Flow Nanobiosensor for Simultaneous Detection of Virus Genotype-Specific PCR Products. JOURNAL OF ANALYTICAL METHODS IN CHEMISTRY 2018; 2018:7691014. [PMID: 29675287 PMCID: PMC5838496 DOI: 10.1155/2018/7691014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 09/05/2017] [Accepted: 11/16/2017] [Indexed: 06/08/2023]
Abstract
Nervous necrosis virus (nodavirus) has been responsible for mass mortalities in aquaculture industry worldwide, with great economic and environmental impact. A rapid low-cost test to identify nodavirus genotype could have important benefits for vaccine and diagnostic applications in small- and medium-scale laboratories in both academia and fish farming industry. A dual lateral flow biosensor for simultaneous detection of the most prevalent nodavirus genotypes (RGNNV and SJNNV) was developed and optimized. The dual biosensor consisted of two antibody-based test zones, indicative of each genotype, and a control zone. The positive signals were visualized by gold nanoparticles functionalized with anti-biotin antibody, and the detection was completed within 20 min. Optimization studies included antibody type and amount determination for test zone construction, gold nanoparticle conjugate type selection for high signal generation, and detection assay parameter determination. Following optimization, the biosensor was evaluated with healthy and RGNNV-nodavirus-infected fish samples. The proposed assay's cost was estimated to be less than 3 €, including the required reagents and biosensor. This work presents important steps towards making a dual lateral flow biosensor for nodavirus genotyping; further evaluation with clinical samples is needed before the test is appropriate for diagnostic kit development.
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Affiliation(s)
- Dimitra K. Toubanaki
- Laboratory of Cellular Immunology, Department of Microbiology, Hellenic Pasteur Institute, 127 Vas. Sofias Ave., 11521 Athens, Greece
| | - Evdokia Karagouni
- Laboratory of Cellular Immunology, Department of Microbiology, Hellenic Pasteur Institute, 127 Vas. Sofias Ave., 11521 Athens, Greece
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26
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Toffan A, Pascoli F, Pretto T, Panzarin V, Abbadi M, Buratin A, Quartesan R, Gijón D, Padrós F. Viral nervous necrosis in gilthead sea bream (Sparus aurata) caused by reassortant betanodavirus RGNNV/SJNNV: an emerging threat for Mediterranean aquaculture. Sci Rep 2017; 7:46755. [PMID: 28462930 PMCID: PMC5411978 DOI: 10.1038/srep46755] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 03/21/2017] [Indexed: 11/23/2022] Open
Abstract
Viral nervous necrosis (VNN) certainly represents the biggest challenge for the sustainability and the development of aquaculture. A large number of economically relevant fish species have proven to be susceptible to the disease. Conversely, gilthead sea bream has generally been considered resistant to VNN, although it has been possible to isolate the virus from apparently healthy sea bream and sporadically from affected larvae and postlarvae. Unexpectedly, in 2014–2016 an increasing number of hatcheries in Europe have experienced mass mortalities in sea bream larvae. Two clinical outbreaks were monitored over this time span and findings are reported in this paper. Despite showing no specific clinical signs, the affected fish displayed high mortality and histological lesions typical of VNN. Fish tested positive for betanodavirus by different laboratory techniques. The isolates were all genetically characterized as being reassortant strains RGNNV/SJNNV. A genetic characterization of all sea bream betanodaviruses which had been isolated in the past had revealed that the majority of the strains infecting sea bream are actually RGNNV/SJNNV. Taken together, this information strongly suggests that RGNNV/SJNNV betanodavirus possesses a particular tropism to sea bream, which can pose a new and unexpected threat to the Mediterranean aquaculture.
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Affiliation(s)
- Anna Toffan
- OIE reference centre for viral encephalopathy and retinopathy, Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Università 10, Legnaro, Padova, Italy
| | - Francesco Pascoli
- OIE reference centre for viral encephalopathy and retinopathy, Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Università 10, Legnaro, Padova, Italy
| | - Tobia Pretto
- Istituto Zooprofilattico Sperimentale delle Venezie, Fish Pathology Department, Via Leonardo da Vinci 39, Adria, Rovigo, Italy.,Department of Veterinary Medical Sciences, Alma Mater Studiorum University of Bologna, Via Tolara di Sopra 50, Ozzano dell'Emilia, Bologna, Italy
| | - Valentina Panzarin
- OIE reference centre for viral encephalopathy and retinopathy, Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Università 10, Legnaro, Padova, Italy
| | - Miriam Abbadi
- OIE reference centre for viral encephalopathy and retinopathy, Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Università 10, Legnaro, Padova, Italy
| | - Alessandra Buratin
- OIE reference centre for viral encephalopathy and retinopathy, Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Università 10, Legnaro, Padova, Italy
| | - Rosita Quartesan
- OIE reference centre for viral encephalopathy and retinopathy, Istituto Zooprofilattico Sperimentale delle Venezie, Viale dell'Università 10, Legnaro, Padova, Italy
| | - Daniel Gijón
- Fish Health Service, Skretting, Ctra. de la Estación S/N, Cojóbar, Spain
| | - Francesc Padrós
- Fish Diseases Diagnostic Service, Facultat de Veterinaria, Universitat Autònoma de Barcelona, Bellaterra, Cerdanyola del Vallès, Spain
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27
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Doan QK, Vandeputte M, Chatain B, Morin T, Allal F. Viral encephalopathy and retinopathy in aquaculture: a review. JOURNAL OF FISH DISEASES 2017; 40:717-742. [PMID: 27633881 DOI: 10.1111/jfd.12541] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 06/23/2016] [Accepted: 06/27/2016] [Indexed: 05/22/2023]
Abstract
Viral encephalopathy and retinopathy (VER), otherwise known as viral nervous necrosis (VNN), is a major devastating threat for aquatic animals. Betanodaviruses have been isolated in at least 70 aquatic animal species in marine and in freshwater environments throughout the world, with the notable exception of South America. In this review, the main features of betanodavirus, including its diversity, its distribution and its transmission modes in fish, are firstly presented. Then, the existing diagnosis and detection methods, as well as the different control procedures of this disease, are reviewed. Finally, the potential of selective breeding, including both conventional and genomic selection, as an opportunity to obtain resistant commercial populations, is examined.
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Affiliation(s)
- Q K Doan
- Ifremer, UMR 9190 MARBEC, Palavas-les-Flots, France
- TNU, Thai Nguyen University of Agriculture and Forestry (TUAF), Quyet Thang Commune, Thai Nguyen City, Vietnam
| | - M Vandeputte
- Ifremer, UMR 9190 MARBEC, Palavas-les-Flots, France
- INRA, GABI, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - B Chatain
- Ifremer, UMR 9190 MARBEC, Palavas-les-Flots, France
| | - T Morin
- Anses, Ploufragan-Plouzané Laboratory, Unit Viral Diseases of Fish, Plouzané, France
| | - F Allal
- Ifremer, UMR 9190 MARBEC, Palavas-les-Flots, France
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28
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Nuñez-Ortiz N, Pascoli F, Picchietti S, Buonocore F, Bernini C, Toson M, Scapigliati G, Toffan A. A formalin-inactivated immunogen against viral encephalopathy and retinopathy (VER) disease in European sea bass (Dicentrarchus labrax): immunological and protection effects. Vet Res 2016; 47:89. [PMID: 27590537 PMCID: PMC5010674 DOI: 10.1186/s13567-016-0376-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 07/26/2016] [Indexed: 12/15/2022] Open
Abstract
The European sea bass (Dicentrarchus labrax) is an important farmed fish species in the Mediterranean area, very sensitive to the infection by encephalopathy and retinopathy virus (VERv), or Betanodavirus, which causes massive mortalities. Effective vaccines to fight the pathology are not yet available and in this work we describe a promising intraperitoneal immunization route against VERv of sea bass juveniles. We performed intraperitoneal and immersion immunization trials with a VERv (isolate 283.2009 RGNNV) inactivated by formalin, β-propiolactone and heat treatment. Interestingly, the intraperitoneal immunization with formalin-inactivated VERv induced a significant antigen-specific IgM production, differently from other inactivation protocols. However, the same formalin-inactivated antigen resulted in very low IgM antibodies when administered by immersion. Following the intraperitoneal injection with formalin-inactivated virus, the quantitative expression of the antiviral MxA gene showed a modulation of transcripts in the gut after 48 h and on head kidney after 24 h, whereas ISG12 gene was significantly up-regulated after 48 h on both tissues. In immersion immunization with formalin-inactivated VERv, a modulation of MxA and ISG12 genes after 24 h post-treatment was detected in the gills. An effective uptake of VERv particles in the gills was confirmed by immunohistochemistry using anti-VERv antibodies. Lastly, in challenge experiments using live VERv after intraperitoneal immunization with formalin-inactivated VERv, we observed a significant increase (81.9%) in relative survival percentage with respect to non-immunized fish, whereas immersion immunization resulted in no protection. Our results suggest that intraperitoneal immunization with formalin-inactivated VERv could be a safe and effective strategy to fight Betanodavirus infection in European sea bass.
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Affiliation(s)
- Noelia Nuñez-Ortiz
- Department for Innovation in Biological, Agro-food and Forest Systems, University of Tuscia, Viterbo, Italy
| | - Francesco Pascoli
- Centro di Referenza Nazionale (NRL) per le patologie dei pesci, molluschi e crostacei, Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro (PD), Italy
| | - Simona Picchietti
- Department for Innovation in Biological, Agro-food and Forest Systems, University of Tuscia, Viterbo, Italy
| | - Francesco Buonocore
- Department for Innovation in Biological, Agro-food and Forest Systems, University of Tuscia, Viterbo, Italy
| | - Chiara Bernini
- Department for Innovation in Biological, Agro-food and Forest Systems, University of Tuscia, Viterbo, Italy
| | - Marica Toson
- Epidemiologia applicata agli animali acquatici, Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro (PD), Italy
| | - Giuseppe Scapigliati
- Department for Innovation in Biological, Agro-food and Forest Systems, University of Tuscia, Viterbo, Italy.
| | - Anna Toffan
- Centro di Referenza Nazionale (NRL) per le patologie dei pesci, molluschi e crostacei, Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro (PD), Italy
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29
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Pascoli F, Serra M, Toson M, Pretto T, Toffan A. Betanodavirus ability to infect juvenile European sea bass, Dicentrarchus labrax, at different water salinity. JOURNAL OF FISH DISEASES 2016; 39:1061-1068. [PMID: 26763095 DOI: 10.1111/jfd.12440] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 10/19/2015] [Accepted: 10/20/2015] [Indexed: 06/05/2023]
Abstract
Viral encephalopathy and retinopathy (VER) is one of the most devastating and economically relevant diseases for marine aquaculture. The presence of betanodavirus in freshwater fish is recorded, but very little is known about VER outbreaks in marine species reared in freshwater. Our study investigated the ability of betanodavirus to cause disease in European sea bass, Dicentrarchus labrax, reared at different salinity levels. Fish were challenged with RGNNV or mock infected by bath at different salinity levels (freshwater, 25‰ and 33‰). Fish were checked twice a day and the dead ones were examined by standard virological techniques, by rRT-PCR and by histochemical and immunohistochemical analyses. All the infected groups showed a significant higher mortality rate than the one of the mock-infected group. VERv presence was confirmed by rRT-PCR. Histochemical and immunohistochemical analyses highlighted the typical lesions associated with VER. Our results highlight that salinity does not affect the ability of betanodavirus to induce clinical signs and mortality in European sea bass infected under experimental conditions. These results underline the great adaptation potential of VERv, which in combination with its already known high environmental resistance and broad host range, may explain the diffusion of this disease and the threat posed to aquaculture worldwide.
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Affiliation(s)
- F Pascoli
- Istituto Zooprofilattico Sperimentale delle Venezie, Centro di Referenza Nazionale (NRL) per le patologie dei pesci, molluschi e crostacei, Legnaro, PD, Italy
| | - M Serra
- Istituto Zooprofilattico Sperimentale delle Venezie, Centro di Referenza Nazionale (NRL) per le patologie dei pesci, molluschi e crostacei, Legnaro, PD, Italy
| | - M Toson
- Istituto Zooprofilattico Sperimentale delle Venezie, Epidemiologia applicata agli animali acquatici, Legnaro, PD, Italy
| | - T Pretto
- Istituto Zooprofilattico Sperimentale delle Venezie, Centro di Referenza Nazionale (NRL) per le patologie dei pesci, molluschi e crostacei, Legnaro, PD, Italy
| | - A Toffan
- Istituto Zooprofilattico Sperimentale delle Venezie, Centro di Referenza Nazionale (NRL) per le patologie dei pesci, molluschi e crostacei, Legnaro, PD, Italy
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30
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Molecular Basis for Antigenic Diversity of Genus Betanodavirus. PLoS One 2016; 11:e0158814. [PMID: 27438093 PMCID: PMC4954670 DOI: 10.1371/journal.pone.0158814] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 06/22/2016] [Indexed: 11/20/2022] Open
Abstract
Betanodaviruses are the causative agents of viral nervous necrosis (VNN), a devastating disease for the Mediterranean mariculture. Four different betanodavirus species are recognized, Striped jack-, Redspotted grouper-, Tiger puffer-, and Barfin flounder nervous necrosis virus (SJNNV, RGNNV, TPNNV and BFNNV), but there is little knowledge on their antigenic properties. In order to describe the serological relationships among different betanodavirus genotypes, serum neutralization assays were performed using rabbit polyclonal antisera against eight fish nodaviruses that cover a wide species-, temporal-, spatial- and genetic range. The results indicate that the SJNNV and RGNNV are antigenically distinct, constituting serotypes A and C, respectively. The TPNNV and BFNNV, the latter representing cold-water betanodaviruses, are antigenically related and cluster within serotype B. The reassortant viruses RGNNV/SJNNV and SJNNV/RGNNV group within serotypes A and C, respectively, indicating that the coat protein encoded by RNA2 acts as major immunoreactivity determinant. Immunostaining of in vitro expressed wild type and chimeric capsid proteins between the RGNNV and the SJNNV species indicated that the C-terminal part of the capsid protein retains the immunoreactive portion. The amino acid (aa) residues determining RGNNV and SJNNV antigenic diversity were mapped to aa residues 217–256 and aa 257–341, respectively. Neutralization of reverse genetics derived chimeric viruses indicated that these areas determine the neutralizing epitopes. The data obtained are crucial for the development of targeted serological tests for the diagnosis of VNN, and informative for development of cross-protective vaccines against various betanodavirus genotypes.
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31
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Nuñez-Ortiz N, Stocchi V, Toffan A, Pascoli F, Sood N, Buonocore F, Picchietti S, Papeschi C, Taddei AR, Thompson KD, Scapigliati G. Quantitative immunoenzymatic detection of viral encephalopathy and retinopathy virus (betanodavirus) in sea bass Dicentrarchus labrax. JOURNAL OF FISH DISEASES 2016; 39:821-831. [PMID: 26610431 DOI: 10.1111/jfd.12415] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Revised: 07/30/2015] [Accepted: 07/31/2015] [Indexed: 06/05/2023]
Abstract
Viral encephalopathy and retinopathy disease caused by betanodavirus, genus of the family Nodaviridae, affects marine, wild and farmed species including sea bass, one of the most important farmed species in Europe. This work describes a reliable and sensitive indirect ELISA assay to detect betanodavirus in biological samples using a polyclonal antiserum (pAb 283) against the 283/I09 virus strain, the most common red-spotted grouper nervous necrosis virus (RGNNV) genotype in the Mediterranean area, and a capture-based ELISA using a monoclonal antibody (mAb 4C3) specific to a common epitope present on the capsid protein. Using adsorbed, purified VERv preparation, the detection limit of indirect ELISA was 2 μg mL(-1) (3 × 10(5) TCID50 per mL), whereas for capture-based ELISA, the sensitivity for the antigen in solution was 17 μg mL(-1) (35 × 10(5) TCID50 per mL). The capture-based ELISA was employed to detect VERv in brain homogenates of in vivo infected sea bass and resulted positive in 22 of 32 samples, some of these with a high viral load estimates (about 1.1 × 10(8) TCID50 per mL). The ELISA system we propose may be helpful in investigations where coupling of viral content in fish tissues with the presence of circulating VERv-specific IgM is required, or for use in samples where PCR is difficult to perform.
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Affiliation(s)
- N Nuñez-Ortiz
- Dipartimento per l'Innovazione nei Sistemi Biologici Agroalimentari e Forestali, Università della Tuscia, Viterbo, Italy
| | - V Stocchi
- Dipartimento per l'Innovazione nei Sistemi Biologici Agroalimentari e Forestali, Università della Tuscia, Viterbo, Italy
| | - A Toffan
- Fish Virology Department, Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro, Padova, Italy
| | - F Pascoli
- Fish Virology Department, Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro, Padova, Italy
| | - N Sood
- National Bureau of Fish Genetic Resources, Lucknow, UP, India
| | - F Buonocore
- Dipartimento per l'Innovazione nei Sistemi Biologici Agroalimentari e Forestali, Università della Tuscia, Viterbo, Italy
| | - S Picchietti
- Dipartimento per l'Innovazione nei Sistemi Biologici Agroalimentari e Forestali, Università della Tuscia, Viterbo, Italy
| | - C Papeschi
- Dipartimento per l'Innovazione nei Sistemi Biologici Agroalimentari e Forestali, Università della Tuscia, Viterbo, Italy
| | - A R Taddei
- Centro di Microscopia Elettronica, Università della Tuscia, Viterbo, Italy
| | - K D Thompson
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Near Edimburgh, Scotland, UK
| | - G Scapigliati
- Dipartimento per l'Innovazione nei Sistemi Biologici Agroalimentari e Forestali, Università della Tuscia, Viterbo, Italy
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Toffan A, Panzarin V, Toson M, Cecchettin K, Pascoli F. Water temperature affects pathogenicity of different betanodavirus genotypes in experimentally challenged Dicentrarchus labrax. DISEASES OF AQUATIC ORGANISMS 2016; 119:231-8. [PMID: 27225206 DOI: 10.3354/dao03003] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Betanodaviruses are the causative agents of a highly infectious disease of fish known as viral nervous necrosis (VNN). To date, 4 different nervous necrosis virus (NNV) genotypes have been described, but natural reassortant viruses have also been detected, which further increase viral variability. Water temperature plays an important role in determining the appearance and the severity of VNN disease. We assessed the effect of temperature (20°, 25° and 30°C) on mortality and virus load in the brain of European sea bass Dicentrarchus labrax experimentally infected with 4 genetically different betanodaviruses, namely red-spotted grouper NNV (RGNNV), striped jack NNV (SJNNV) and the reassortant strains RGNNV/SJNNV and SJNNV/RGNNV. The RGNNV/SJNNV virus possesses the polymerase gene of RGNNV and the coat protein gene of SJNNV, and vice versa for the SJNNV/RGNNV virus. The obtained results showed that the RGNNV strain is the most pathogenic for juvenile sea bass, but clinical disease and mortality appeared only at higher temperatures. The SJNNV strain is weakly pathogenic for D. labrax regardless of the temperature used, while virus replication was detected in the brain of survivors only at 20°C. Finally, reassortant strains caused low mortality, independent of the temperature used, but the viral load in the brain was strongly influenced by water temperature and the genetic type of the polymerase gene. Taken together, these data show that nodavirus replication in vivo is a composite process regulated by both the genetic features of the viral strain and water temperatures.
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Affiliation(s)
- Anna Toffan
- Istituto Zooprofilattico Sperimentale delle Venezie, National Reference Centre for Fish, Mollusk and Crustacean Diseases, Viale dell'Università 10, 35020 Legnaro (PD), Italy
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Cell Culture Isolation of Piscine Nodavirus (Betanodavirus) in Fish-Rearing Seawater. Appl Environ Microbiol 2016; 82:2537-2544. [PMID: 26896128 DOI: 10.1128/aem.03834-15] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 02/11/2016] [Indexed: 11/20/2022] Open
Abstract
Piscine nodavirus (betanodavirus) is the causative agent of viral nervous necrosis (VNN) in a variety of cultured fish species, particularly marine fish. In the present study, we developed a sensitive method for cell culture isolation of the virus from seawater and applied the method to a spontaneous fish-rearing environment. The virus in seawater was concentrated by an iron-based flocculation method and subjected to isolation with E-11 cells. A real-time reverse transcriptase PCR (RT-PCR) assay was used to quantify the virus in water. After spiking into seawater was performed, a betanodavirus strain (red spotted grouper nervous necrosis virus [RGNNV] genotype) was effectively recovered in the E-11 cells at a detection limit of approximately 10(5)copies (equivalent to 10(2)50% tissue culture infective doses [TCID50])/liter seawater. In an experimental infection of juvenile sevenband grouper (Epinephelus septemfasciatus) with the virus, the virus was isolated from the drainage of a fish-rearing tank when the virus level in water was at least approximately 10(5)copies/liter. The application of this method to seven band grouper-rearing floating net pens, where VNN prevailed, resulted in the successful isolation of the virus from seawater. No differences were found in the partial sequences of the coat protein gene (RNA2) between the clinical virus isolates of dead fish and the cell-cultured virus isolates from seawater, and the viruses were identified as RGNNV. The infection experiment showed that the virus isolates from seawater were virulent to seven band grouper. These results showed direct evidence of the horizontal transmission of betanodavirus via rearing water in marine aquaculture.
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Carballo C, Garcia-Rosado E, Borrego JJ, Alonso MC. SJNNV down-regulates RGNNV replication in European sea bass by the induction of the type I interferon system. Vet Res 2016; 47:6. [PMID: 26743933 PMCID: PMC4705746 DOI: 10.1186/s13567-015-0304-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2015] [Accepted: 04/17/2015] [Indexed: 01/09/2023] Open
Abstract
European sea bass is highly susceptible to the betanodavirus RGNNV genotype, although the SJNNV genotype has also been detected in this fish species. The coexistence of both genotypes may affect the replication of both viruses by viral interaction or by stimulation of the host antiviral defense system in which the IFN I system plays a key role. IFN I triggers the transcription of interferon-stimulated genes, including Mx genes, whose expression has been used as a reporter of IFN I activity. The present study evaluated the effect of a primary exposure to an SJNNV isolate on a subsequent RGNNV infection and analyzed the role of the IFN I system in controlling VNNV infections in sea bass using different in vivo approaches. VNNV infection and Mx transcription were comparatively evaluated after single infections, superinfection (SJ+RG) and co-infection (poly I:C+RG). The single RGNNV infection resulted in a 24% survival rate, whereas the previous SJNNV or poly I:C inoculation increased the survival rate up to 96 and 100%, respectively. RGNNV replication in superinfection was reduced compared with RGNNV replication after a single inoculation. Mx transcription analysis shows differential induction of the IFN I system by both isolates. SJNNV was a potent Mx inducer, whereas RGNNV induced lower Mx transcription and did not interfere with the IFN I system triggered by SJNNV or poly I:C. This study demonstrates that an antiviral state exists after SJNNV and poly I:C injection, suggesting that the IFN I system plays an important role against VNNV infections in sea bass.
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Affiliation(s)
- Carlos Carballo
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga, 29071, Málaga, Spain. .,IFAPA centro El Toruño, Junta de Andalucía, El Puerto de Santa María, Cádiz, Spain.
| | - Esther Garcia-Rosado
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga, 29071, Málaga, Spain.
| | - Juan J Borrego
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga, 29071, Málaga, Spain.
| | - M Carmen Alonso
- Departamento de Microbiología, Facultad de Ciencias, Universidad de Málaga, 29071, Málaga, Spain.
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Toubanaki DK, Margaroni M, Karagouni E. Development of a Novel Allele-Specific PCR Method for Rapid Assessment of Nervous Necrosis Virus Genotypes. Curr Microbiol 2015. [DOI: 10.1007/s00284-015-0880-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Souto S, Lopez-Jimena B, Alonso MC, García-Rosado E, Bandín I. Experimental susceptibility of European sea bass and Senegalese sole to different betanodavirus isolates. Vet Microbiol 2015; 177:53-61. [PMID: 25770892 DOI: 10.1016/j.vetmic.2015.02.030] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Revised: 02/18/2015] [Accepted: 02/23/2015] [Indexed: 10/23/2022]
Abstract
The susceptibility of juvenile European sea bass and Senegalese sole to three VNNV isolates (a reassortant RGNNV/SJNNV, as well as the parental RGNNV and SJNNV genotypes) has been evaluated by challenges using two inoculation ways (bath and intramuscular injection). The results demonstrate that these two fish species are susceptible to all the VNNV isolates tested. In European sea bass, RGNNV caused the highest cumulative mortality, reaching maximum values of viral RNA and titres. Although the SJNNV isolate did not provoke mortality or clinical signs of disease in this fish species, viral production in survivor fish was determined; on the other hand the reassortant isolate did cause mortality and clinical signs of disease, although less evident than those recorded after RGNNV infection. These results suggest that the changes suffered by the SJNNV RNA2 segment of the reassortant isolate, compared to the parental SJNNV, may have involved host-specificity and/or virulence determinants for European sea bass. Regarding Senegalese sole, although the three isolates caused 100% mortality, the reassortant strain provoked the most acute symptoms, and more quickly, especially in the bath challenge. This was also the isolate showing less difference between the number of RNA copies and viral titre, reaching the highest titres of infective viral particles in nervous tissue of infected animals. The RGNNV isolate produced the lowest values of infective viral particles. All these results suggest that the RGNNV and the reassortant isolates are the most suited for infecting European sea bass and Senegalese sole, respectively.
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Affiliation(s)
- S Souto
- Universidad de Santiago de Compostela, Instituto de Acuicultura, Constantino Candeira C.P.: 15705, Santiago de Compostela, A Coruña, Spain.
| | - B Lopez-Jimena
- IFAPA Centro El Toruño, Junta de Andalucía, Ctra N.IV, Camino de Tiro Pichón, C.P.: 11.500, El Puerto de Santa María, Cádiz, Spain
| | - M C Alonso
- Universidad de Málaga, Departamento de Microbiología, Facultad de Ciencias, Campus de Teatinos, 29.071 Málaga, Spain
| | - E García-Rosado
- Universidad de Málaga, Departamento de Microbiología, Facultad de Ciencias, Campus de Teatinos, 29.071 Málaga, Spain
| | - I Bandín
- Universidad de Santiago de Compostela, Instituto de Acuicultura, Constantino Candeira C.P.: 15705, Santiago de Compostela, A Coruña, Spain
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He M, Teng CB. Divergence and codon usage bias of Betanodavirus, a neurotropic pathogen in fish. Mol Phylogenet Evol 2015; 83:137-42. [DOI: 10.1016/j.ympev.2014.11.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Revised: 11/25/2014] [Accepted: 11/30/2014] [Indexed: 11/17/2022]
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Zorriehzahra MJ, Nazari A, Ghasemi M, Ghiasi M, Karsidani SH, Bovo G, Daud HHM. Vacuolating encephalopathy and retinopathy associated with a nodavirus-like agent: a probable cause of mass mortality of wild Golden grey mullet (Liza aurata) and Sharpnose grey mullet (Liza saliens) in Iranian waters of the Caspian Sea. Virusdisease 2014; 25:430-6. [PMID: 25674618 DOI: 10.1007/s13337-014-0238-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Accepted: 10/29/2014] [Indexed: 11/26/2022] Open
Abstract
Mullets are dominant fishes in the catch composition in the southern coasts of the Caspian Sea and after (Rutilus frisii kutum Kamensky, 1901) have a worthy role in production of marine proteins and incomings of north provinces of Iran. Mullets stocks decreased dramatically in recent decades in the Caspian Sea and catch amount reached from 6446 MT on 2002 to 2151 MT in 2012. Mysterious mortalities occurred in wild mullet (Liza auratu) and (Liza saliens) in Iranian waters of Caspian Sea in recent years. Regarding to investigation of causative agent of mentioned outbreak about 322 suspected samples were collected from coastal capture sites of Iranian north provinces in 2008 till 2011. Moribund fish revealed skin darkening, erratic swimming, belly-up at rest and high distension of swim bladder. Target tissues such as brain and eye were removed and then fixed for histopathology and TEM assay. Widespread and massive vacuolation were observed in brain, spinal cord, retina and optical nerve and intracytoplasmic vacuoles and virus particles in retina. So concerning to clinical signs, histopathological and TEM findings, it could be concluded that nodavirus-like agent could be probable cause of mass mortality of wild mullet in Iranian waters of the Caspian Sea.
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Affiliation(s)
- Mohammad Jalil Zorriehzahra
- Aquatic animal Health & Diseases Dept, Iranian Fisheries Research Organization (IFRO), Hemmat Highway, Azad shahr Ave., Sarve azad St., West 8th, Botanical National Blvd, Tehran, Iran
| | - Alireza Nazari
- Falavarjan Branch, Islamic Azad University, Falavarjan, Isfahan Iran
| | | | | | | | - Giuseppe Bovo
- Instituto Zooprofilattico Sperimentale delle Venezie, Padua, Italy
| | - Hassan Hj Mohd Daud
- Faculty of Veterinary Medicine, University of Putra Malaysia (UPM), Serdang, Malaysia
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A unique nodavirus with novel features: mosinovirus expresses two subgenomic RNAs, a capsid gene of unknown origin, and a suppressor of the antiviral RNA interference pathway. J Virol 2014; 88:13447-59. [PMID: 25210176 DOI: 10.1128/jvi.02144-14] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
UNLABELLED Insects are a reservoir for many known and novel viruses. We discovered an unknown virus, tentatively named mosinovirus (MoNV), in mosquitoes from a tropical rainforest region in Côte d'Ivoire. The MoNV genome consists of two segments of positive-sense RNA of 2,972 nucleotides (nt) (RNA 1) and 1,801 nt (RNA 2). Its putative RNA-dependent RNA polymerase shares 43% amino acid identity with its closest relative, that of the Pariacoto virus (family Nodaviridae). Unexpectedly, for the putative capsid protein, maximal pairwise identity of 16% to Lake Sinai virus 2, an unclassified virus with a nonsegmented RNA genome, was found. Moreover, MoNV virions are nonenveloped and about 50 nm in diameter, larger than any of the known nodaviruses. Mature MoNV virions contain capsid proteins of ∼ 56 kDa, which do not seem to be cleaved from a longer precursor. Northern blot analyses revealed that MoNV expresses two subgenomic RNAs of 580 nt (RNA 3) and 292 nt (RNA 4). RNA 4 encodes a viral suppressor of RNA interference (RNAi) that shares its mechanism with the B2 RNAi suppressor protein of other nodaviruses despite lacking recognizable similarity to these proteins. MoNV B2 binds long double-stranded RNA (dsRNA) and, accordingly, inhibits Dicer-2-mediated processing of dsRNA into small interfering RNAs (siRNAs). Phylogenetic analyses indicate that MoNV is a novel member of the family Nodaviridae that acquired its capsid gene via reassortment from an unknown, distantly related virus beyond the family level. IMPORTANCE The identification of novel viruses provides important information about virus evolution and diversity. Here, we describe an unknown unique nodavirus in mosquitoes, named mosinovirus (MoNV). MoNV was classified as a nodavirus based on its genome organization and on phylogenetic analyses of the RNA-dependent RNA polymerase. Notably, its capsid gene was acquired from an unknown virus with a distant relationship to nodaviruses. Another remarkable feature of MoNV is that, unlike other nodaviruses, it expresses two subgenomic RNAs (sgRNAs). One of the sgRNAs expresses a protein that counteracts antiviral defense of its mosquito host, whereas the function of the other sgRNA remains unknown. Our results show that complete genome segments can be exchanged beyond the species level and suggest that insects harbor a large repertoire of exceptional viruses.
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Panzarin V, Cappellozza E, Mancin M, Milani A, Toffan A, Terregino C, Cattoli G. In vitro study of the replication capacity of the RGNNV and the SJNNV betanodavirus genotypes and their natural reassortants in response to temperature. Vet Res 2014; 45:56. [PMID: 24885997 PMCID: PMC4050099 DOI: 10.1186/1297-9716-45-56] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Accepted: 04/24/2014] [Indexed: 11/10/2022] Open
Abstract
Betanodaviruses are the causative agents of viral nervous necrosis and affect a broad range of fish species worldwide. Their bi-segmented genome is composed of the RNA1 and the RNA2 molecules encoding the viral polymerase and the coat protein, respectively. In southern Europe the presence of the RGNNV and the SJNNV genotypes, and the RGNNV/SJNNV and RGNNV/SJNNV reassortants has been documented. Several studies have reported a correlation between water temperature and disease onset. To explore the replication efficiency of betanodaviruses with different genomes in relation to temperature and to understand the role of genetic reassortment on viral phenotype, RGNNV, SJNNV, RGNNV/SJNNV and RGNNV/SJNNV field isolates were fully sequenced, and growth curves generated in vitro at four different temperatures (15, 20, 25, 30 °C) were developed for each isolate. The data obtained, corroborated by statistical analysis, demonstrated that viral titres of diverse betanodavirus genotypes varied significantly in relation to the incubation temperature of the culture. In particular, at 30 °C betanodaviruses under investigation presented different phenotypes, and viruses containing the RNA1 of the RGNNV genotype showed the best replication efficiency. Laboratory results demonstrated that viruses clustering within the same genotype based on the polymerase gene, possess similar growth kinetics in response to temperature, thus highlighting the key role of RNA1 in controlling viral replication at different environmental conditions. The results generated might have practical implications for the inference of viral phenotype according to genetic features and may contribute to a better understanding of betanodavirus ecology.
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Affiliation(s)
- Valentina Panzarin
- Istituto Zooprofilattico Sperimentale delle Venezie, OIE Reference Laboratory for Viral Encephalopathy and Retinopathy, Viale dell'Università 10, 35020 Legnaro, PD, Italy.
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