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Vakharia VN, Ammayappan A, Yusuff S, Tesfaye TM, Kurath G. Heterologous Exchanges of Glycoprotein and Non-Virion Protein in Novirhabdoviruses: Assessment of Virulence in Yellow Perch ( Perca flavescens) and Rainbow Trout ( Oncorhynchus mykiss). Viruses 2024; 16:652. [PMID: 38675990 PMCID: PMC11054476 DOI: 10.3390/v16040652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Revised: 04/15/2024] [Accepted: 04/19/2024] [Indexed: 04/28/2024] Open
Abstract
Infectious hematopoietic necrosis virus (IHNV) and viral hemorrhagic septicemia virus (VHSV) are rhabdoviruses in two different species belonging to the Novirhabdovirus genus. IHNV has a narrow host range restricted to trout and salmon species, and viruses in the M genogroup of IHNV have high virulence in rainbow trout (Oncorhynchus mykiss). In contrast, the VHSV genotype IVb that invaded the Great Lakes in the United States has a broad host range, with high virulence in yellow perch (Perca flavescens), but not in rainbow trout. By using reverse-genetic systems of IHNV-M and VHSV-IVb strains, we generated six IHNV:VHSV chimeric viruses in which the glycoprotein (G), non-virion-protein (NV), or both G and NV genes of IHNV-M were replaced with the analogous genes from VHSV-IVb, and vice versa. These chimeric viruses were used to challenge groups of rainbow trout and yellow perch. The parental recombinants rIHNV-M and rVHSV-IVb were highly virulent in rainbow trout and yellow perch, respectively. Parental rIHNV-M was avirulent in yellow perch, and chimeric rIHNV carrying G, NV, or G and NV genes from VHSV-IVb remained low in virulence in yellow perch. Similarly, the parental rVHSV-IVb exhibited low virulence in rainbow trout, and chimeric rVHSV with substituted G, NV, or G and NV genes from IHNV-M remained avirulent in rainbow trout. Thus, the G and NV genes of either virus were not sufficient to confer high host-specific virulence when exchanged into a heterologous species genome. Some exchanges of G and/or NV genes caused a loss of host-specific virulence, providing insights into possible roles in viral virulence or fitness, and interactions between viral proteins.
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Affiliation(s)
- Vikram N. Vakharia
- Institute of Marine & Environmental Technology, University of Maryland Baltimore County, Baltimore, MD 21202, USA; (A.A.); (S.Y.)
| | - Arun Ammayappan
- Institute of Marine & Environmental Technology, University of Maryland Baltimore County, Baltimore, MD 21202, USA; (A.A.); (S.Y.)
| | - Shamila Yusuff
- Institute of Marine & Environmental Technology, University of Maryland Baltimore County, Baltimore, MD 21202, USA; (A.A.); (S.Y.)
| | | | - Gael Kurath
- U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA 98115, USA
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Bergh Ø, Boutrup TS, Johansen R, Skall HF, Sandlund N, Olesen NJ. Viral Haemorrhagic Septicemia Virus (VHSV) Isolated from Atlantic Herring, Clupea harengus, Causes Mortality in Bath Challenge on Juvenile Herring. Viruses 2023; 15:152. [PMID: 36680192 PMCID: PMC9866969 DOI: 10.3390/v15010152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 12/22/2022] [Accepted: 12/31/2022] [Indexed: 01/06/2023] Open
Abstract
Viral hemorrhagic septicaemia virus (VHSV) has been demonstrated to cause high mortalities in a wide range of teleosts, farmed as well as wild. In Europe, VHSV of genotypes Ib, Id, II, and III have been detected in wild fish, including Atlantic herring Clupea harengus, but disease outbreaks have not been observed in Atlantic herring and the effects on wild stocks are not well documented. Here, we have tested two VHSV isolates from herring (genotypes Ib and III, from the western coasts of Norway and Denmark, respectively) in a challenge experiment with herring (mean weight 2.59 g, SD 0.71 g) caught on the west coast of Denmark. The Norwegian genotype Ib isolate (NO-F-CH/2009) showed an accumulated mortality of 47% compared to 6% mortality with the Danish genotype III isolate 4p168 and zero in the unchallenged control group. In both groups, we found positive rt-RT-PCR and positive immunohistochemistry of VHSV from days 6 and 8 onward. With both isolates, the organs mainly affected were the heart and kidney. The results demonstrate the susceptibility of Atlantic herring to VHSV, and both genotypes gave pathological findings in several organs. Genotype III showed a low mortality rate, and the importance of this genotype for herring is therefore not determined. Genotype Ib showed both high prevalence and mortality, and this genotype is therefore likely to have a negative effect on wild Atlantic herring stocks. Further examinations to determine how VHSV can affect wild Atlantic herring stocks are needed.
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Affiliation(s)
- Øivind Bergh
- Institute of Marine Research, P.O. Box 1870 Nordnes, 5817 Bergen, Norway
| | - Torsten Snogdal Boutrup
- National Institute of Aquatic Resources, Section for Fish and Crustacean Diseases, Technical University of Denmark, 2800 Lyngby, Denmark
| | - Renate Johansen
- Norwegian Veterinary Institute, P.O. Box 64, 1431 Ås, Norway
| | - Helle Frank Skall
- National Institute of Aquatic Resources, Section for Fish and Crustacean Diseases, Technical University of Denmark, 2800 Lyngby, Denmark
| | - Nina Sandlund
- Institute of Marine Research, P.O. Box 1870 Nordnes, 5817 Bergen, Norway
| | - Niels Jørgen Olesen
- National Institute of Aquatic Resources, Section for Fish and Crustacean Diseases, Technical University of Denmark, 2800 Lyngby, Denmark
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Swaminathan TR, Johny TK, Nithianantham SR, Sudhagar A, Pradhan PK, S R KS, Nair RR, Sood N. A natural outbreak of infectious spleen and kidney necrosis virus (ISKNV) threatens wild pearlspot, Etroplus suratensis in Peechi Dam in the Western Ghats biodiversity hotspot, India. Transbound Emerg Dis 2022; 69:e1595-e1605. [PMID: 35235241 DOI: 10.1111/tbed.14494] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 02/18/2022] [Accepted: 02/20/2022] [Indexed: 11/27/2022]
Abstract
A large-scale mortality of pearlspot, Etroplus suratensis was reported from Peechi Dam, an artificial tropical lake made for irrigation and drinking water supply in Kerala, India during 2018. This dam is located in the premises of Western Ghats, recognized as one of the biodiversity hotspots of the world. The objective of this study was to identify the aetiological agent of this large-scale mortality of E. suratensis by systematic diagnostic investigation and identification of pathogen. Virus isolation was carried out on a species-specific pearlspot fin (PSF) cell line. Infected PSF cells showed cytopathic effects (CPE) like cell shrinkage, rounding, enlargement, clustering, and subsequent detachment of cells with a high viral titre of 106⋅95 TCID50 mL-1 at 8 days post inoculation (dpi). Histopathological examination of the fish showed the presence of numerous abnormal enlarged basophilic cells and intracytoplasmic eosinophilic inclusions in the liver. Moreover, transmission electron microscopy (TEM) analysis revealed the presence of large numbers of 125-132 nm viral particles in the spleen tissues. PCR amplification and phylogenetic analysis of the major capsid protein (MCP) gene sequence confirmed that the causative agent was Infectious spleen and kidney necrosis virus (ISKNV) of the genus Megalocytivirus. The experimental infection recorded 86.7±2.7% mortality in the E. suratensis (body weight - 11.01±2.7 g; body length 8.01±2.23 cm) injected with 1 × 104⋅25 TCID50 mL-1 ISKNV per fish. Our detailed investigation provided definitive diagnosis of ISKNV in the severe mass mortality event in wild E. suratensis in Peechi Dam, India, adding one more species to expanding host range of ISKNV infection. The high mortality rate of ISKNV infection in pearlspot suggests the perilous nature of this disease, particularly among the wild fish population. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Thangaraj Raja Swaminathan
- Peninsular and Marine Fish Genetic Resources Centre, ICAR-NBFGR, CMFRI Campus, Kochi, Kerala, 682 018, India
| | - Tina Kollannoor Johny
- Peninsular and Marine Fish Genetic Resources Centre, ICAR-NBFGR, CMFRI Campus, Kochi, Kerala, 682 018, India
| | - Sundar Raj Nithianantham
- Peninsular and Marine Fish Genetic Resources Centre, ICAR-NBFGR, CMFRI Campus, Kochi, Kerala, 682 018, India
| | - Arun Sudhagar
- Peninsular and Marine Fish Genetic Resources Centre, ICAR-NBFGR, CMFRI Campus, Kochi, Kerala, 682 018, India
| | - Pravata Kumar Pradhan
- ICAR National Bureau of Fish Genetic Resources, Lucknow, Uttar Pradesh, 226002, India
| | - Krupesha Sharma S R
- ICAR Central Marine Fisheries Research Institute, Kochi, Kerala, 682 018, India
| | - Reshma R Nair
- Peninsular and Marine Fish Genetic Resources Centre, ICAR-NBFGR, CMFRI Campus, Kochi, Kerala, 682 018, India
| | - Neeraj Sood
- ICAR National Bureau of Fish Genetic Resources, Lucknow, Uttar Pradesh, 226002, India
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Niner MD, Stepien CA, Gorgoglione B, Leaman DW. Genomic and immunogenic changes of Piscine novirhabdovirus (Viral Hemorrhagic Septicemia Virus) over its evolutionary history in the Laurentian Great Lakes. PLoS One 2021; 16:e0232923. [PMID: 34048438 PMCID: PMC8162641 DOI: 10.1371/journal.pone.0232923] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 04/22/2021] [Indexed: 01/21/2023] Open
Abstract
A unique and highly virulent subgenogroup (-IVb) of Piscine novirhabdovirus, also known as Viral Hemorrhagic Septicemia Virus (VHSV), suddenly appeared in the Laurentian Great Lakes, causing large mortality outbreaks in 2005 and 2006, and affecting >32 freshwater fish species. Periods of apparent dormancy have punctuated smaller and more geographically-restricted outbreaks in 2007, 2008, and 2017. In this study, we conduct the largest whole genome sequencing analysis of VHSV-IVb to date, evaluating its evolutionary changes from 48 isolates in relation to immunogenicity in cell culture. Our investigation compares genomic and genetic variation, selection, and rates of sequence changes in VHSV-IVb, in relation to other VHSV genogroups (VHSV-I, VHSV-II, VHSV-III, and VHSV-IVa) and with other Novirhabdoviruses. Results show that the VHSV-IVb isolates we sequenced contain 253 SNPs (2.3% of the total 11,158 nucleotides) across their entire genomes, with 85 (33.6%) of them being non-synonymous. The most substitutions occurred in the non-coding region (NCDS; 4.3%), followed by the Nv- (3.8%), and M- (2.8%) genes. Proportionally more M-gene substitutions encoded amino acid changes (52.9%), followed by the Nv- (50.0%), G- (48.6%), N- (35.7%) and L- (23.1%) genes. Among VHSV genogroups and subgenogroups, VHSV-IVa from the northeastern Pacific Ocean has shown the fastest substitution rate (2.01x10-3), followed by VHSV-IVb (6.64x10-5) and by the VHSV-I, -II and-III genogroups from Europe (4.09x10-5). A 2016 gizzard shad (Dorosoma cepedianum) from Lake Erie possessed the most divergent VHSV-IVb sequence. The in vitro immunogenicity analysis of that sample displayed reduced virulence (as did the other samples from 2016), in comparison to the original VHSV-IVb isolate (which had been traced back to 2003, as an origin date). The 2016 isolates that we tested induced milder impacts on fish host cell innate antiviral responses, suggesting altered phenotypic effects. In conclusion, our overall findings indicate that VHSV-IVb has undergone continued sequence change and a trend to lower virulence over its evolutionary history (2003 through present-day), which may facilitate its long-term persistence in fish host populations.
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Affiliation(s)
- Megan D. Niner
- Department of Environmental Sciences, University of Toledo, Toledo, Ohio, United States of America
| | - Carol A. Stepien
- School of Oceanography, University of Washington, Seattle, WA, United States of America
- Genetics and Genomics Group, NOAA Pacific Marine Environmental Laboratory, Seattle, Washington, United States of America
- * E-mail: ,
| | - Bartolomeo Gorgoglione
- Department of Biological Sciences, University of Toledo, Toledo, Ohio, United States of America
| | - Douglas W. Leaman
- Department of Biological Sciences, University of Toledo, Toledo, Ohio, United States of America
- Department of Biological Sciences, Wright State University, Dayton, Ohio, United States of America
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López-Vázquez C, Bandín I, Dopazo CP. Design and Evaluation of a Macroarray for Detection, Identification, and Typing of Viral Hemorrhagic Septicemia Virus (VHSV). Animals (Basel) 2021; 11:841. [PMID: 33809757 PMCID: PMC8002285 DOI: 10.3390/ani11030841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 03/11/2021] [Accepted: 03/12/2021] [Indexed: 11/17/2022] Open
Abstract
The viral hemorrhagic septicemia virus (VHSV) is the causative agent of an important disease in freshwater and marine fishes. Its diagnosis officially relies on the isolation of the virus in cell culture and its identification by serological or polymerase chain reaction (PCR) methodologies. Nowadays, reverse transcription real-time quantitative PCR (RT-qPCR) is the most widely employed technique for the detection of this virus and some studies have reported the validation of RT-qPCR procedures for the detection, typing, and quantification of VHSV isolates. However, although the efficacy of this technique is not in doubt, it can be cumbersome and even impractical when it comes to processing large numbers of samples, a situation in which cross-contamination problems cannot be ruled out. In the present study, we have designed and validated a macroarray for the simultaneous detection, typing, and quantification of VHSV strains. Its analytical sensitivity (5-50 TCID50/mL), analytical specificity (intra and intergroup), efficiency (E = 100.0-101.1) and reliability (repeatability and reproducibility with CV < 5%, and standard curves with R2 < 0.95) with strains from any VHSV genotype have been widely demonstrated. The procedure is based on the 'binary multiplex RT-qPCR system (bmRT-qPCR)' previously reported by the same team, applied to arrays of 96-well PCR strip tubes plates, which can be stored at -25 °C for three months and up to one year before their use, without significant loss of efficiency.
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Affiliation(s)
- Carmen López-Vázquez
- Unidad de Ictiopatología, Instituto de Acuicultura y Departamento de Microbiología, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Isabel Bandín
- Unidad de Ictiopatología, Instituto de Acuicultura y Departamento de Microbiología, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - Carlos P Dopazo
- Unidad de Ictiopatología, Instituto de Acuicultura y Departamento de Microbiología, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
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Stepien CA, Niner MD. Evolutionary trajectory of fish Piscine novirhabdovirus (=Viral Hemorrhagic Septicemia Virus) across its Laurentian Great Lakes history: Spatial and temporal diversification. Ecol Evol 2020; 10:9740-9775. [PMID: 33005343 PMCID: PMC7520192 DOI: 10.1002/ece3.6611] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 05/04/2020] [Accepted: 05/10/2020] [Indexed: 02/05/2023] Open
Abstract
Piscine novirhabdovirus = Viral Hemorrhagic Septicemia Virus (VHSV) first appeared in the Laurentian Great Lakes with large outbreaks from 2005 to 2006, as a new and novel RNA rhabdovirus subgenogroup (IVb) that killed >30 fish species. Interlude periods punctuated smaller more localized outbreaks in 2007, 2010, and 2017, although some fishes tested positive in the intervals. There have not been reports of outbreaks or positives from 2018, 2019, or 2020. Here, we employ a combined population genetics and phylogenetic approach to evaluate spatial and temporal evolutionary trajectory on its G-gene sequence variation, in comparison with whole-genome sequences (11,083 bp) from a subset of 44 individual isolates (including 40 newly sequenced ones). Our results show that IVb (N = 184 individual fish isolates) diversified into 36 G-gene haplotypes from 2003 to 2017, stemming from two originals ("a" and "b"). G-gene haplotypes "a" and "b" differed by just one synonymous single-nucleotide polymorphism (SNP) substitution, remained the most abundant until 2011, then disappeared. Group "a" descendants (14 haplotypes) remained most prevalent in the Upper and Central Great Lakes, with eight (51%) having nonsynonymous substitutions. Group "b" descendants primarily have occurred in the Lower Great Lakes, including 22 haplotypes, of which 15 (68%) contained nonsynonymous changes. Evolutionary patterns of the whole-genome sequences (which had 34 haplotypes among 44 isolates) appear congruent with those from the G-gene. Virus populations significantly diverged among the Upper, Central, and Lower Great Lakes, diversifying over time. Spatial divergence was apparent in the overall patterns of nucleotide substitutions, while amino acid changes increased temporally. VHSV-IVb thus significantly differentiated across its less than two decades in the Great Lakes, accompanied by declining outbreaks and virulence. Continuing diversification likely allowed the virus to persist at low levels in resident fish populations, and may facilitate its potential for further and future spread to new habitats and nonacclimated hosts.
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Affiliation(s)
- Carol A. Stepien
- Genetics and Genomics Group (G3)NOAA Pacific Marine Environmental Laboratory (PMEL)SeattleWAUSA
| | - Megan D. Niner
- Genetics and Genomics Group (G3), Department of Environmental SciencesUniversity of ToledoToledoOHUSA
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Detection of Koi Herpesvirus (KHV) and Carp Oedema Virus (CEV) in Invasive Round Goby, Neogobius Melanostomus Pallas, 1814, from Poland and Germany. J Vet Res 2020; 64:247-251. [PMID: 32587911 PMCID: PMC7305641 DOI: 10.2478/jvetres-2020-0037] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Accepted: 05/14/2020] [Indexed: 11/20/2022] Open
Abstract
Introduction The aim of the study was to determine the transmission potential of carp edema virus (CEV) and koi herpesvirus (KHV) introduced to Europe by the invasive round goby (Neogobius melanostomus). Material and Methods A total of 70 round goby specimens were collected from the Szczecin Lagoon, Poland, and locations in Germany in the third and fourth quarters of 2018. The fish were analysed to detect KHV and CEV by PCR. Results Six fish specimens were positive for the presence of KHV, while none of the gobies examined showed the presence of CEV. Conclusion The CEV genome was detected in the goby specimens from Germany and from Poland. Considering the high pace of the spread of the round goby and its effectiveness in acquisition of new ecological niches, it should be kept out during refilling of carp ponds. Further studies should focus on experimental cohabitation of CEV-infected round gobies and specific-pathogen-free (SPF) carp to investigate the potential for active virus transfer.
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Effect of the Viral Hemorrhagic Septicemia Virus Nonvirion Protein on Translation via PERK-eIF2α Pathway. Viruses 2020; 12:v12050499. [PMID: 32365817 PMCID: PMC7290495 DOI: 10.3390/v12050499] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 04/27/2020] [Accepted: 04/28/2020] [Indexed: 12/28/2022] Open
Abstract
Viral hemorrhagic septicemia virus (VHSV) is one of the most deadly infectious fish pathogens, posing a serious threat to the aquaculture industry and freshwater ecosystems worldwide. Previous work showed that VHSV sub-genotype IVb suppresses host innate immune responses, but the exact mechanism by which VHSV IVb inhibits antiviral response remains incompletely characterized. As with other novirhabdoviruses, VHSV IVb contains a unique and highly variable nonvirion (NV) gene, which is implicated in viral replication, virus-induced apoptosis and regulating interferon (IFN) production. However, the molecular mechanisms underlying the role of IVb NV gene in regulating viral or cellular processes is poorly understood. Compared to the wild-type recombinant (rWT) VHSV, mutant VHSV lacking a functional IVb NV reduced IFN expression and compromised innate immune response of the host cells by inhibiting translation. VHSV IVb infection increased phosphorylated eukaryotic initiation factor 2α (p-eIF2α), resulting in host translation shutoff. However, VHSV IVb protein synthesis proceeds despite increasing phosphorylation of eIF2α. During VHSV IVb infection, eIF2α phosphorylation was mediated via PKR-like endoplasmic reticulum kinase (PERK) and was required for efficient viral protein synthesis, but shutoff of host translation and IFN signaling was independent of p-eIF2α. Similarly, IVb NV null VHSV infection induced less p-eIF2α, but exhibited decreased viral protein synthesis despite increased levels of viral mRNA. These findings show a role for IVb NV in VHSV pathogenesis by utilizing the PERK-eIF2α pathway for viral-mediated host shutoff and interferon signaling to regulate host cell response.
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The Nucleoprotein and Phosphoprotein Are Major Determinants of the Virulence of Viral Hemorrhagic Septicemia Virus in Rainbow Trout. J Virol 2019; 93:JVI.00382-19. [PMID: 31270224 DOI: 10.1128/jvi.00382-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2019] [Accepted: 06/23/2019] [Indexed: 01/08/2023] Open
Abstract
Viral hemorrhagic septicemia virus (VHSV), a fish rhabdovirus, infects several marine and freshwater fish species. There are many strains of VHSV that affect different fish, but some strains of one genetic subgroup have gained high virulence in rainbow trout (Oncorhynchus mykiss). To define the genetic basis of high virulence in trout, we used reverse genetics to create chimeric VHSVs in which viral nucleoprotein (N), P (phosphoprotein), or M (matrix protein) genes, or the N and P genes, were exchanged between a trout-virulent European VHSV strain (DK-3592B) and a trout-avirulent North American VHSV strain (MI03). Testing of the chimeric recombinant VHSV (rVHSV) by intraperitoneal injection in juvenile rainbow trout showed that exchanges of the viral P or M genes had no effect on the trout virulence phenotype of either parental strain. However, reciprocal exchanges of the viral N gene resulted in a partial gain of function in the chimeric trout-avirulent strain (22% mortality) and complete loss of virulence for the chimeric trout-virulent strain (2% mortality). Reciprocal exchanges of both the N and P genes together resulted in complete gain of function in the chimeric avirulent strain (82% mortality), again with complete loss of virulence in the chimeric trout-virulent strain (0% mortality). Thus, the VHSV N gene contains an essential determinant of trout virulence that is strongly enhanced by the viral P gene. We hypothesize that the host-specific virulence mechanism may involve increased efficiency of the viral polymerase complex when the N and P proteins have adapted to more efficient interaction with a host component from rainbow trout.IMPORTANCE Rainbow trout farming is a major food source industry worldwide that has suffered great economic losses due to host jumps of fish rhabdovirus pathogens, followed by evolution of dramatic increases in trout-specific virulence. However, the genetic determinants of host jumps and increased virulence in rainbow trout are unknown for any fish rhabdovirus. Previous attempts to identify the viral genes containing trout virulence determinants of viral hemorrhagic septicemia virus (VHSV) have not been successful. We show here that, somewhat surprisingly, the viral nucleocapsid (N) and phosphoprotein (P) genes together contain the determinants responsible for trout virulence in VHSV. This suggests a novel host-specific virulence mechanism involving the viral polymerase and a host component. This differs from the known virulence mechanisms of mammalian rhabdoviruses based on the viral P or M (matrix) protein.
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Getchell RG, First EJ, Bogdanowicz SM, Andrés JA, Schulman AT, Kramer J, Eckerlin GE, Farrell JM, Marquis H. Investigation of round goby viral haemorrhagic septicaemia outbreak in New York. JOURNAL OF FISH DISEASES 2019; 42:1023-1033. [PMID: 31025373 DOI: 10.1111/jfd.13003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Revised: 03/19/2019] [Accepted: 03/20/2019] [Indexed: 06/09/2023]
Abstract
Eleven viral haemorrhagic septicaemia virus (VHSV) genotype IVb isolates were sequenced, and their genetic variation explored to determine the source of a VHS outbreak on the eastern shore of Cayuga Lake. An active fish kill of round gobies (Neogobius melanostomus, Pallas) was intensively sampled at King Ferry, NY and nearby Long Point State Park in May 2017. Gross lesions observed on 67 moribund round gobies and two rock bass (Ambloplites rupestris, Rafinesque) included moderately haemorrhagic internal organs and erythematous areas on the head, flank, and fins. RT-qPCR tests for VHSV were positive for all 69 fish. Viral isolation on epithelioma papulosum cyprinid cells showed cytopathic effect characteristic of VHSV for six round goby samples from King Ferry. The complete nucleotide sequence of the VHSV IVb genomes of five Cayuga Lake round goby isolates were derived on an Illumina platform along with 2017 VHSV IVb isolates from round gobies collected from the following: Lake Erie near Dunkirk, NY; the St. Lawrence River near Clayton and Cape Vincent, NY; and Lake St. Lawrence near Massena, NY. The phylogenetic tree created from these aligned sequences and four other complete VHSV IVb genomes shows Cayuga Lake isolates are closely related to the Lake Erie isolates.
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Affiliation(s)
- Rodman G Getchell
- Aquatic Animal Health Program, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York
| | - Erika J First
- Aquatic Animal Health Program, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York
| | - Steven M Bogdanowicz
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York
| | - Jose A Andrés
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York
| | - Adam T Schulman
- Aquatic Animal Health Program, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York
| | - Jordan Kramer
- Aquatic Animal Health Program, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York
| | - Geofrey E Eckerlin
- Rome Field Station, New York State Department of Environmental Conservation, Rome, New York
| | - John M Farrell
- Department of Environmental and Forest Biology, College of Environmental Science and Forestry, State University of New York, Syracuse, New York
| | - Hélène Marquis
- Aquatic Animal Health Program, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, New York
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Yusuff S, Kurath G, Kim MS, Tesfaye TM, Li J, McKenney DG, Vakharia VN. The glycoprotein, non-virion protein, and polymerase of viral hemorrhagic septicemia virus are not determinants of host-specific virulence in rainbow trout. Virol J 2019; 16:31. [PMID: 30845963 PMCID: PMC6407216 DOI: 10.1186/s12985-019-1139-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 02/27/2019] [Indexed: 01/06/2023] Open
Abstract
Background Viral hemorrhagic septicemia virus (VHSV), a fish rhabdovirus belonging to the Novirhabdovirus genus, causes severe disease and mortality in many marine and freshwater fish species worldwide. VHSV isolates are classified into four genotypes and each group is endemic to specific geographic regions in the north Atlantic and Pacific Oceans. Most viruses in the European VHSV genotype Ia are highly virulent for rainbow trout (Oncorhynchus mykiss), whereas, VHSV genotype IVb viruses from the Great Lakes region in the United States, which caused high mortality in wild freshwater fish species, are avirulent for trout. This study describes molecular characterization and construction of an infectious clone of the virulent VHSV-Ia strain DK-3592B from Denmark, and application of the clone in reverse genetics to investigate the role of selected VHSV protein(s) in host-specific virulence in rainbow trout (referred to as trout-virulence). Methods Overlapping cDNA fragments of the DK-3592B genome were cloned after RT-PCR amplification, and their DNA sequenced by the di-deoxy chain termination method. A full-length cDNA copy (pVHSVdk) of the DK-3592B strain genome was constructed by assembling six overlapping cDNA fragments by using natural or artificially created unique restriction sites in the overlapping regions of the clones. Using an existing clone of the trout-avirulent VHSV-IVb strain MI03 (pVHSVmi), eight chimeric VHSV clones were constructed in which the coding region(s) of the glycoprotein (G), non-virion protein (NV), G and NV, or G, NV and L (polymerase) genes together, were exchanged between the two clones. Ten recombinant VHSVs (rVHSVs) were generated, including two parental rVHSVs, by transfecting fish cells with ten individual full-length plasmid constructs along with supporting plasmids using the established protocol. Recovered rVHSVs were characterized for viability and growth in vitro and used to challenge groups of juvenile rainbow trout by intraperitoneal injection. Results Complete sequence of the VHSV DK-3592B genome was determined from the cloned cDNA and deposited in GenBank under the accession no. KC778774. The trout-virulent DK-3592B genome (genotype Ia) is 11,159 nt in length and differs from the trout-avirulent MI03 genome (pVHSVmi) by 13% at the nucleotide level. When the rVHSVs were assessed for the trout-virulence phenotype in vivo, the parental rVHSVdk and rVHSVmi were virulent and avirulent, respectively, as expected. Four chimeric rVHSVdk viruses with the substitutions of the G, NV, G and NV, or G, NV and L genes from the avirulent pVHSVmi constructs were still highly virulent (100% mortality), while the reciprocal four chimeric rVHSVmi viruses with genes from pVHSVdk remained avirulent (0–10% mortality). Conclusions When chimeric rVHSVs, containing all the G, NV, and L gene substitutions, were tested in vivo, they did not exhibit any change in trout-virulence relative to the background clones. These results demonstrate that the G, NV and L genes of VHSV are not, by themselves or in combination, major determinants of host-specific virulence in trout.
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Affiliation(s)
- Shamila Yusuff
- Institute of Marine & Environmental Technology, University of Maryland Baltimore County, 701 E. Pratt Street, Baltimore, MD, 21202, USA.,GeneDX 207 Perry Parkway, Gaithersburg, MD, 20877, USA
| | - Gael Kurath
- U.S. Geological Survey, Western Fisheries Research Center, 6505 NE 65th Street, Seattle, WA, 98115, USA
| | - Min Sun Kim
- U.S. Geological Survey, Western Fisheries Research Center, 6505 NE 65th Street, Seattle, WA, 98115, USA.,Department of Integrative Bio-Industrial Engineering, Sejong University, Seoul, Republic of South Korea
| | - Tarin M Tesfaye
- U.S. Geological Survey, Western Fisheries Research Center, 6505 NE 65th Street, Seattle, WA, 98115, USA
| | - Jie Li
- Institute of Marine & Environmental Technology, University of Maryland Baltimore County, 701 E. Pratt Street, Baltimore, MD, 21202, USA
| | - Douglas G McKenney
- U.S. Geological Survey, Western Fisheries Research Center, 6505 NE 65th Street, Seattle, WA, 98115, USA
| | - Vikram N Vakharia
- Institute of Marine & Environmental Technology, University of Maryland Baltimore County, 701 E. Pratt Street, Baltimore, MD, 21202, USA.
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12
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Phelps NBD, Bueno I, Poo-Muñoz DA, Knowles SJ, Massarani S, Rettkowski R, Shen L, Rantala H, Phelps PLF, Escobar LE. Retrospective and Predictive Investigation of Fish Kill Events. JOURNAL OF AQUATIC ANIMAL HEALTH 2019; 31:61-70. [PMID: 30735267 DOI: 10.1002/aah.10054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 10/21/2018] [Indexed: 06/09/2023]
Abstract
Fish kill investigations are critical to understanding threats to aquatic ecosystems and can serve as a measure of environmental disruption as well as an early indicator of emerging disease. The goal of this study was to analyze historical data related to such events among wild fish populations in Minnesota in order to assess the quality and completeness of the data and potential trends in fish kills. After excluding events with incomplete data (e.g., in which the location was not reported), we analyzed 225 unique fish kills from 2003 to 2013 that were recorded in two Minnesota Department of Natural Resources databases. The most reported fish kills occurred during 2007 (n = 41) and during the month of June (n = 81) across all years. Centrarchid species were present in the most fish kills (138), followed by cyprinid and ictalurid species, which were present in 53 and 40 events, respectively. Environmental factors were the most common cause of death reported. Models of environmental factors revealed that the maximum nighttime land surface temperature was the most critical factor in fish mortality, followed by changes in primary productivity and human disturbances. During the course of this study, data gaps were identified, including underreporting, inconsistent investigation, and the lack of definitive diagnoses, making interpretation of our results challenging. Even so, understanding these historical trends and data gaps can be useful in generating hypotheses and advancing data collection systems for investigating future fish kills. Our study is a primer investigation of fish kills providing information on the plausible areas, seasons, and fish groups at risk that can guide active environmental monitoring and epidemiological surveillance of fishes.
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Affiliation(s)
- Nicholas B D Phelps
- Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, 1365 Gortner Avenue, St. Paul, Minnesota, 55108, USA
- Department of Fisheries, Wildlife, and Conservation Biology, University of Minnesota, 2003 Upper Buford Circle, St. Paul, Minnesota, 55108, USA
| | - Irene Bueno
- Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, 1365 Gortner Avenue, St. Paul, Minnesota, 55108, USA
| | - Daniela A Poo-Muñoz
- Grupo de Ecología y Diversidad Biológica, Facultad de Recursos Naturales y Medicina Veterinaria, Universidad Santo Tomás, Sede Temuco, Manuel Rodríguez 060, Temuco, Chile
- Escuela de Medicina Veterinaria, Facultad de Ciencias, Universidad Mayor, Chile
| | - Sarah J Knowles
- Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, 1365 Gortner Avenue, St. Paul, Minnesota, 55108, USA
| | - Sarah Massarani
- Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, 1365 Gortner Avenue, St. Paul, Minnesota, 55108, USA
| | - Rebecca Rettkowski
- Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, 1365 Gortner Avenue, St. Paul, Minnesota, 55108, USA
| | - Ling Shen
- Minnesota Department of Natural Resources, 500 Lafayette Road, St. Paul, Minnesota, 55155, USA
| | - Heidi Rantala
- Minnesota Department of Natural Resources, 500 Lafayette Road, St. Paul, Minnesota, 55155, USA
| | - Paula L F Phelps
- Minnesota Department of Natural Resources, 500 Lafayette Road, St. Paul, Minnesota, 55155, USA
| | - Luis E Escobar
- Department of Fisheries, Wildlife, and Conservation Biology, University of Minnesota, 2003 Upper Buford Circle, St. Paul, Minnesota, 55108, USA
- Department of Fish and Wildlife Conservation, Virginia Tech, Blacksburg, Virginia, 24061, USA
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13
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Vennerström P, Välimäki E, Hautaniemi M, Lyytikäinen T, Kapiainen S, Vidgren G, Virtala AM. Wild fish are negligible transmitters of viral haemorrhagic septicaemia virus (VHSV) genotype Id in the VHS restriction zone in Finland. DISEASES OF AQUATIC ORGANISMS 2018; 131:187-197. [PMID: 30459291 DOI: 10.3354/dao03301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Wild fish were suspected to be the source of reinfection by viral haemorrhagic septicaemia virus (VHSV) in Finnish brackish water rainbow trout farms located in a restriction zone regarding viral haemorrhagic septicaemia (VHS) comprising the entire Province of Åland, Baltic Sea, in the 2000s. Altogether, 1636 wild fish of 17 different species living in the vicinity of infected fish farms were screened for VHSV during the years 2005-2008. Additionally, 2 uninfected wild fish species as well as farmed whitefish were introduced into a VHS-positive fish farm to test whether they became infected by VHSV from the clinically diseased rainbow trout. Wild fish did not test positive for VHSV on any occasion. In contrast, whitefish introduced to a VHS-positive farm were infected with VHSV genotype Id and started to replicate the virus for a short time during the trial. Whitefish are farmed together with, or in the vicinity of, farmed rainbow trout in the study area and, according to this study, are a possible source of the recurring infection in the restriction area. A sprivivirus was isolated from all fish species in the infection trial without causing mortality in the test groups.
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Affiliation(s)
- Pia Vennerström
- Production Animal and Wildlife Health Research Unit, Finnish Food Safety Authority, 00790 Helsinki, Finland
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14
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Pham PH, Sokeechand BSH, Garver KA, Jones G, Lumsden JS, Bols NC. Fish viruses stored in RNAlater can remain infectious and even be temporarily protected from inactivation by heat or by tissue homogenates. J Virol Methods 2017; 253:31-37. [PMID: 29288073 DOI: 10.1016/j.jviromet.2017.12.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 12/18/2017] [Accepted: 12/24/2017] [Indexed: 10/18/2022]
Abstract
RNAlater is a commonly used transport and storage solution for samples collected for fish health investigations, particularly those potentially involving viruses. However, the infectivity of fish viruses after storage in RNAlater have not been determined. Nevertheless, knowledge of pathogen infectivity of preserved samples is crucial for ensuring safe transport and storage protocols. Therefore, the infectivity of three fish RNA viruses in RNAlater was examined at four temperatures: -80 °C, 4 °C, room temperature (RT, approximately 22 °C) and 37 °C. The viruses were viral hemorrhagic septicemia virus (VHSV), infectious pancreatic necrosis virus (IPNV) and chum salmon reovirus (CSV). Overall, three consistent outcomes were observed. First, all three viruses remained infectious in RNAlater at RT or lower. High log titres of these viruses remained over 30 d of storage in either RNAlater or PBS. Second, RNAlater delayed the thermal inactivation of these viruses when compared to PBS at 37 °C. For VHSV, the titre remained high in RNAlater after one day of incubation at 37 °C, but was inactivated to below threshold in PBS over the same period. For IPNV, the titre remained high in RNAlater after 30 d of incubation at 37 °C, but was inactivated to below threshold in PBS over the same period. For CSV, the titre was slightly higher in RNAlater than PBS at 37 °C over 7 d, and by day 30, only samples stored in RNAlater proved infectious at titres above the detection threshold. Third, RNAlater delayed the inactivation of these viruses when they were stored together with head kidney homogenates. For VHSV, infectious virus was recovered from samples stored at 4 °C in RNAlater by day 7 of incubation, whereas it was inactivated to below threshold in PBS over the same period. For both IPNV and CSV, infectious virus was recovered from samples stored at 37 °C in RNAlater for 7 d, but not so in PBS. In summary, fish viruses can remain infectious and are even temporarily protected from inactivation while in RNAlater. This makes RNAlater a potentially useful solution for the transport of fish viruses. At the same time, precautionary measures must be taken when transporting potentially infectious samples in RNAlater.
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Affiliation(s)
- Phuc H Pham
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
| | | | - Kyle A Garver
- Pacific Biological Station, Department of Fisheries and Oceans, Nanaimo, British Columbia, Canada
| | - Ginny Jones
- Elanco Canada Limited, Aqua Business R&D, Victoria, PEI, Canada
| | - John S Lumsden
- Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada; St. George's University, True Blue, Grenada
| | - Niels C Bols
- Department of Biology, University of Waterloo, Waterloo, ON, Canada.
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15
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Getchell RG, Cornwell ER, Bogdanowicz S, Andrés J, Batts WN, Kurath G, Breyta R, Choi JG, Farrell JM, Bowser PR. Complete sequences of 4 viral hemorrhagic septicemia virus IVb isolates and their virulence in northern pike fry. DISEASES OF AQUATIC ORGANISMS 2017; 126:211-227. [PMID: 29160219 DOI: 10.3354/dao03171] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Four viral hemorrhagic septicemia virus (VHSV) genotype IVb isolates were sequenced, their genetic variation explored, and comparative virulence assayed with experimental infections of northern pike Esox lucius fry. In addition to the type strain MI03, the complete 11183 bp genome of the first round goby Neogobius melanostomus isolate from the St. Lawrence River, and the 2013 and 2014 isolates from gizzard shad Dorosoma cepedianum die-offs in Irondequoit Bay, Lake Ontario and Dunkirk Harbor, Lake Erie were all deep sequenced on an Illumina platform. Mutations documented in the 11 yr since the MI03 index case from Lake St. Clair muskellunge Esox masquinongy showed 87 polymorphisms among the 4 isolates. Twenty-six mutations were non-synonymous and located at 18 different positions within the matrix protein, glycoprotein, non-virion protein, and RNA polymerase genes. The same 4 isolates were used to infect northern pike fry by a single 1 h bath exposure. Cumulative percent mortality varied from 42.5 to 62.5%. VHSV was detected in 57% (41/72) of the survivors at the end of the 21-d trial, suggesting that the virus was not rapidly cleared. Lesions were observed in many of the moribund and dead northern pike, such as hemorrhaging in the skin and fins, as well as hydrocephalus. Mean viral load measured from the trunk and visceral tissues of MI03-infected pike was significantly higher than the quantities detected in fish infected with the most recent isolates of genotype IVb, but there were no differences in cumulative mortality observed.
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Affiliation(s)
- Rodman G Getchell
- Aquatic Animal Health Program, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
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16
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Vennerström P, Välimäki E, Lyytikäinen T, Hautaniemi M, Vidgren G, Koski P, Virtala AM. Viral haemorrhagic septicaemia virus (VHSV Id) infections are detected more consistently using syndromic vs. active surveillance. DISEASES OF AQUATIC ORGANISMS 2017; 126:111-123. [PMID: 29044041 DOI: 10.3354/dao03161] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The eradication of viral haemorrhagic septicaemia virus (VHSV Id) from Finnish brackish-water rainbow trout Oncorhynchus mykiss farms located in the restriction zone in the Province of Åland, Baltic Sea, failed several times in the 2000s. The official surveillance programme was often unable to find VHSV-positive populations, leading to the misbelief in the fish farming industry that virus eradication could be achieved. The ability of 3 other surveillance programmes to detect infected fish populations was compared with the official programme. One programme involved syndromic surveillance based on the observation of clinical disease signs by fish farmers, while 2 programmes comprised active surveillance similar to the official programme, but included increased sampling frequencies and 2 additional tests. The syndromic surveillance concentrated on sending in samples for analysis when any sign of a possible infectious disease at water temperatures below 15°C was noticed. This programme clearly outperformed active surveillance. A real-time reverse transcriptase-polymerase chain reaction method proved to be at least as sensitive as virus isolation in cell culture in detecting acute VHSV infections. An ELISA method was used to test fish serum for antibodies against VHSV. The ELISA method may be a useful tool in VHSV eradication for screening populations during the follow-up period, before declaring an area free of infection.
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Affiliation(s)
- Pia Vennerström
- Veterinary Bacteriology and Pathology Research Unit, Finnish Food Safety Authority, 00790 Helsinki, Finland
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17
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Role of Viral Hemorrhagic Septicemia Virus Matrix (M) Protein in Suppressing Host Transcription. J Virol 2017; 91:JVI.00279-17. [PMID: 28747493 DOI: 10.1128/jvi.00279-17] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 07/13/2017] [Indexed: 12/12/2022] Open
Abstract
Viral hemorrhagic septicemia virus (VHSV) is a pathogenic fish rhabdovirus found in discrete locales throughout the Northern Hemisphere. VHSV infection of fish cells leads to upregulation of the host's virus detection response, but the virus quickly suppresses interferon (IFN) production and antiviral gene expression. By systematically screening each of the six VHSV structural and nonstructural genes, we identified matrix protein (M) as the virus' most potent antihost protein. Only M of VHSV genotype IV sublineage b (VHSV-IVb) suppressed mitochondrial antiviral signaling protein (MAVS) and type I IFN-induced gene expression in a dose-dependent manner. M also suppressed the constitutively active simian virus 40 (SV40) promoter and globally decreased cellular RNA levels. Chromatin immunoprecipitation (ChIP) studies illustrated that M inhibited RNA polymerase II (RNAP II) recruitment to gene promoters and decreased RNAP II C-terminal domain (CTD) Ser2 phosphorylation during VHSV infection. However, transcription directed by RNAP I to III was suppressed by M. To identify regions of functional importance, M proteins from a variety of VHSV strains were tested in cell-based transcriptional inhibition assays. M of a particular VHSV-Ia strain, F1, was significantly less potent than IVb M at inhibiting SV40/luciferase (Luc) expression yet differed by just 4 amino acids. Mutation of D62 to alanine alone, or in combination with an E181-to-alanine mutation (D62A E181A), dramatically reduced the ability of IVb M to suppress host transcription. Introducing either M D62A or D62A E181A mutations into VHSV-IVb via reverse genetics resulted in viruses that replicated efficiently but exhibited less cytotoxicity and reduced antitranscriptional activities, implicating M as a primary regulator of cytopathicity and host transcriptional suppression.IMPORTANCE Viruses must suppress host antiviral responses to replicate and spread between hosts. In these studies, we identified the matrix protein of the deadly fish novirhabdovirus VHSV as a critical mediator of host suppression during infection. Our studies indicated that M alone could block cellular gene expression at very low expression levels. We identified several subtle mutations in M that were less potent at suppressing host transcription. When these mutations were engineered back into recombinant viruses, the resulting viruses replicated well but elicited less toxicity in infected cells and activated host innate immune responses more robustly. These data demonstrated that VHSV M plays an important role in mediating both virus-induced cell toxicity and viral replication. Our data suggest that its roles in these two processes can be separated to design effective attenuated viruses for vaccine candidates.
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18
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Throckmorton E, Brenden T, Peters AK, Newcomb TJ, Whelan GE, Faisal M. Potential Reservoirs and Risk Factors for VHSV IVb in an Enzootic System: Budd Lake, Michigan. JOURNAL OF AQUATIC ANIMAL HEALTH 2017; 29:31-42. [PMID: 28166454 DOI: 10.1080/08997659.2016.1254121] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Viral hemorrhagic septicemia virus genotype IVb (VHSV IVb) has caused major, sporadic fish die-offs in the Laurentian Great Lakes region of North America since 2005. Presently, factors affecting VHSV IVb persistence in enzootic systems are not well understood. Even with annual surveillance, the virus can go undetected for several years after an outbreak before again re-emerging, which suggests that the virus is maintained in the system either below detectable levels or in untested reservoirs. The aim of this study was to identify potential reservoirs of VHSV IVb in Budd Lake, Michigan; VHSV IVb was first detected in Budd Lake in 2007 but remained undetected until 2011. Additionally, we explored the susceptibility of naive fish introduced into a water body enzootic for VHSV IVb by stocking age-0 Largemouth Bass Micropterus salmoides at varying densities into enclosures in the lake. The virus was not detected among samples of the fishes Notropis spp. and Lepomis spp., cylindrical papershell mussels Anodontoides ferussacianus, leeches (subclass Hirudinea), sediment, or water. However, the virus was successfully isolated from amphipods (family Hyalellidae) and Largemouth Bass held in the enclosures. Our finding of VHSV IVb in Hyalellidae amphipods in combination with other research that has detected the virus in Diporeia spp., a large benthic amphipod important as a food resource to Great Lake fishes, suggests that benthic macroinvertebrates are a reservoir for VHSV IVb in infected systems. If there are environmental reservoirs for VHSV IVb in infected systems, they are likely unevenly distributed. Findings of this study add to our understanding of the seemingly complex ecology of this deadly and economically detrimental virus. Received February 22, 2016; accepted October 16, 2016.
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Affiliation(s)
- Elizabeth Throckmorton
- a Department of Fisheries and Wildlife , Michigan State University , 480 Wilson Road, East Lansing , Michigan 48824 , USA
| | - Travis Brenden
- b Quantitative Fisheries Center, Department of Fisheries and Wildlife , Michigan State University , 293 Farm Lane, East Lansing , Michigan 48824 , USA
| | - Amber K Peters
- a Department of Fisheries and Wildlife , Michigan State University , 480 Wilson Road, East Lansing , Michigan 48824 , USA
| | - Tammy J Newcomb
- c Michigan Department of Natural Resources , Post Office Box 30028, 525 West Allegan Street, Lansing , Michigan 48933 , USA
| | - Gary E Whelan
- d Michigan Department of Natural Resources, Fisheries Division , Post Office Box 30446, Lansing , Michigan 48909 , USA
| | - Mohamed Faisal
- a Department of Fisheries and Wildlife , Michigan State University , 480 Wilson Road, East Lansing , Michigan 48824 , USA
- e Department of Pathobiology and Diagnostic Investigation , Michigan State University , 1129 Farm Lane, East Lansing , Michigan 48824 , USA
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19
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Escobar LE, Kurath G, Escobar-Dodero J, Craft ME, Phelps NBD. Potential distribution of the viral haemorrhagic septicaemia virus in the Great Lakes region. JOURNAL OF FISH DISEASES 2017; 40:11-28. [PMID: 27173916 DOI: 10.1111/jfd.12490] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 03/19/2016] [Accepted: 03/21/2016] [Indexed: 06/05/2023]
Abstract
Viral haemorrhagic septicaemia virus (VHSV) genotype IVb has been responsible for large-scale fish mortality events in the Great Lakes of North America. Anticipating the areas of potential VHSV occurrence is key to designing epidemiological surveillance and disease prevention strategies in the Great Lakes basin. We explored the environmental features that could shape the distribution of VHSV, based on remote sensing and climate data via ecological niche modelling. Variables included temperature measured during the day and night, precipitation, vegetation, bathymetry, solar radiation and topographic wetness. VHSV occurrences were obtained from available reports of virus confirmation in laboratory facilities. We fit a Maxent model using VHSV-IVb reports and environmental variables under different parameterizations to identify the best model to determine potential VHSV occurrence based on environmental suitability. VHSV reports were generated from both passive and active surveillance. VHSV occurrences were most abundant near shore sites. We were, however, able to capture the environmental signature of VHSV based on the environmental variables employed in our model, allowing us to identify patterns of VHSV potential occurrence. Our findings suggest that VHSV is not at an ecological equilibrium and more areas could be affected, including areas not in close geographic proximity to past VHSV reports.
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Affiliation(s)
- L E Escobar
- Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, USA
- Minnesota Aquatic Invasive Species Research Center, University of Minnesota, St. Paul, MN, USA
| | - G Kurath
- U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA, USA
| | - J Escobar-Dodero
- Facultad de Ecología y Recursos Naturales, Universidad Andres Bello, Santiago, Chile
| | - M E Craft
- Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, USA
| | - N B D Phelps
- Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, USA
- Minnesota Aquatic Invasive Species Research Center, University of Minnesota, St. Paul, MN, USA
- Veterinary Diagnostic Laboratory, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, USA
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20
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Vázquez D, López-Vázquez C, Skall HF, Mikkelsen SS, Olesen NJ, Dopazo CP. A novel multiplex RT-qPCR method based on dual-labelled probes suitable for typing all known genotypes of viral haemorrhagic septicaemia virus. JOURNAL OF FISH DISEASES 2016; 39:467-482. [PMID: 25952496 DOI: 10.1111/jfd.12381] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 03/25/2015] [Accepted: 03/26/2015] [Indexed: 06/04/2023]
Abstract
Viral haemorrhagic septicaemia (VHS) is a notifiable fish disease, whose causative agent is a rhabdovirus isolated from a wide range of fish species, not only in fresh but also in marine and brackish waters. Phylogenetic studies have identified four major genotypes, with a strong geographical relationship. In this study, we have designed and validated a new procedure--named binary multiplex RT-qPCR (bmRT-qPCR)--for simultaneous detection and typing of all four genotypes of VHSV by real-time RT-PCR based on dual-labelled probes and composed by two multiplex systems designed for European and American/Asiatic isolates, respectively, using a combination of three different fluorophores. The specificity of the procedure was assessed by including a panel of 81 VHSV isolates covering all known genotypes and subtypes of the virus, and tissue material from experimentally infected rainbow trout, resulting in a correct detection and typing of all strains. The analytical sensitivity was evaluated in a comparative assay with titration in cell culture, observing that both methods provided similar limits of detection. The proposed method can be a powerful tool for epidemiological analysis of VHSV by genotyping unknown samples within a few hours.
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Affiliation(s)
- D Vázquez
- Aquaculture Institute, Santiago de Compostela University, 15782, Santiago de Compostela, Spain
| | - C López-Vázquez
- Aquaculture Institute, Santiago de Compostela University, 15782, Santiago de Compostela, Spain
| | - H F Skall
- National Veterinary Institute, Technical University of Denmark, Copenhagen, Denmark
| | - S S Mikkelsen
- National Veterinary Institute, Technical University of Denmark, Copenhagen, Denmark
| | - N J Olesen
- National Veterinary Institute, Technical University of Denmark, Copenhagen, Denmark
| | - C P Dopazo
- Aquaculture Institute, Santiago de Compostela University, 15782, Santiago de Compostela, Spain
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21
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Ito T, Kurita J, Mori KI, Olesen NJ. Virulence of viral haemorrhagic septicaemia virus (VHSV) genotype III in rainbow trout. Vet Res 2016; 47:4. [PMID: 26743807 PMCID: PMC4705761 DOI: 10.1186/s13567-015-0303-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 07/24/2015] [Indexed: 12/03/2022] Open
Abstract
In general, viral haemorrhagic septicaemia virus (VHSV) isolates from marine fish species in European waters (genotypes GIb, GII and GIII) are non- to low virulent in rainbow trout. However, a VHSV isolation was made in 2007 from a disease outbreak in sea farmed rainbow trout in Norway. The isolate, named NO-2007-50-385, was demonstrated to belong to GIII. This isolate has attracted attention to assess which of the viral genome/proteins might be associated with the virulence in rainbow trout. In this study, we describe the difference of virulence in rainbow trout between the NO-2007-50-385 and 4p168 isolates as representatives of virulent and non-virulent GIII isolates, respectively. Rainbow trout were bath challenged with VHSV NO-2007-50-385 for 1 and 6 h, resulting in cumulative mortalities of 5 and 35%, respectively. No mortality was observed in the rainbow trout groups immersed with the genotype III VHSV isolate 4p168 for 1 and 6 h. The viral titre in organs from fish challenged with NO-2007-50-385 for 6 h increased more rapidly than those exposed for 1 h. By in vitro studies it was demonstrated that the final titres of VHSV DK-3592B (GI), NO-2007-50-385 and 4p168 inoculated on EPC cells were very similar, whereas when inoculated on the rainbow trout cell line RTG-2 the titre of the non-virulent 4p168 isolate was 3–4 logs below the two other VHSV isolates. Based on a comparative analysis of the entire genome of the genotype III isolates, we suggest that substitutions of amino acids in positions 118–123 of the nucleo-protein are candidates for being related to virulence of VHSV GIII in rainbow trout.
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Affiliation(s)
- Takafumi Ito
- Tamaki Laboratory, Aquatic Animal Health Division, National Research Institute of Aquaculture, Fisheries Research Agency, 224-1 Hiruda, Tamaki, Mie, Japan.
| | - Jun Kurita
- Tamaki Laboratory, Aquatic Animal Health Division, National Research Institute of Aquaculture, Fisheries Research Agency, 224-1 Hiruda, Tamaki, Mie, Japan.
| | - Koh-ichiro Mori
- Aquatic Animal Health Division, National Research Institute of Aquaculture, Fisheries Research Agency, 422-1 Nakatsuhamaura, Minami-Ise, Mie, Japan.
| | - Niels J Olesen
- National Veterinary Institute, Technical University of Denmark, Bülowsvej 27, 1870, Frederiksberg C, Denmark.
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Grice J, Reid A, Peterson A, Blackburn K, Tubbs L, Lord S, Huber P, Horricks R, Dixon B, Bols NC, Lumsden JS. Walleye Sander vitreus (Mitchill) are relatively resistant to experimental infection with VHSV IVb and extant walleye strains vary in susceptibility. JOURNAL OF FISH DISEASES 2015; 38:859-872. [PMID: 25219756 DOI: 10.1111/jfd.12298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Revised: 07/03/2014] [Accepted: 05/07/2014] [Indexed: 06/03/2023]
Abstract
Compared to fathead minnow, walleye demonstrate low susceptibility to experimental infection with VHSV IVb, regardless of route of exposure or water temperature at time of infection. In triplicate and duplicate groups, walleye were intraperitoneally (i.p.) injected (102 -108 pfu/fish) or waterborne-exposed (w; 1.4 × 107 pfu mL-1 ) with VHSV IVb. High cumulative mortality (64-100%) and severe gross lesions associated with VHSV IVb infection were evident only in fish i.p. injected with 108 pfu at 12 °C. These fish had multifocal necrosis of several tissues including the gill and heart. There was no difference in mortality between walleye infected (w or i.p.) at 12 °C (spring stocking) compared with a declining temperature profile from 18 to 12 °C (fall stocking). There were significant differences (P < 0.05) in mortality between four extant walleye strains following i.p. infection, indicating that the choice of walleye strain for stocking might be an important consideration. Viral antigen was found in both i.p. and w-exposed walleye using immunohistochemistry, mostly within the gill and skin of w-exposed fish and most prominently in dermal fibrocytes. VHSV IVb was detected in multiple tissues from 6 to 21 days post-infection using reverse transcriptase quantitative polymerase chain reaction (RT-qPCR).
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Affiliation(s)
- J Grice
- Fish Pathology Laboratory, Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
| | - A Reid
- Fish Pathology Laboratory, Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
| | - A Peterson
- Fish Pathology Laboratory, Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
| | - K Blackburn
- Fish Pathology Laboratory, Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
| | - L Tubbs
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
| | - S Lord
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
| | - P Huber
- Fish Pathology Laboratory, Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
| | - R Horricks
- Fish Pathology Laboratory, Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
| | - B Dixon
- Novartis Animal Health Inc., Victoria, PEI, Canada
| | - N C Bols
- Novartis Animal Health Inc., Victoria, PEI, Canada
| | - J S Lumsden
- Fish Pathology Laboratory, Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
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Wilson-Rothering A, Marcquenski S, Koenigs R, Bruch R, Kamke K, Isermann D, Thurman A, Toohey-Kurth K, Goldberg T. Temporal Variation in Viral Hemorrhagic Septicemia Virus Antibodies in Freshwater Drum (Aplodinotus grunniens) Indicates Cyclic Transmission in Lake Winnebago, Wisconsin. J Clin Microbiol 2015; 53:2889-94. [PMID: 26135873 PMCID: PMC4540894 DOI: 10.1128/jcm.00010-15] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Accepted: 06/20/2015] [Indexed: 11/20/2022] Open
Abstract
Viral hemorrhagic septicemia virus (VHSV) is an emerging pathogen that causes mass mortality in multiple fish species. In 2007, the Great Lakes freshwater strain, type IVb, caused a large die-off of freshwater drum (Aplodinotus grunniens) in Lake Winnebago, Wisconsin, USA. To evaluate the persistence and transmission of VHSV, freshwater drum from Lake Winnebago were tested for antibodies to the virus using recently developed virus neutralization (VN) and enzyme-linked immunosorbent (ELISA) assays. Samples were also tested by real-time reverse transcription-PCR (rRT-PCR) to detect viral RNA. Of 548 serum samples tested, 44 (8.03%) were positive by VN (titers ranging from 1:16 to 1:1,024) and 45 (8.21%) were positive by ELISA, including 7 fish positive by both assays. Antibody prevalence increased with age and was higher in one northwestern area of Lake Winnebago than in other areas. Of 3,864 tissues sampled from 551 fish, 1 spleen and 1 kidney sample from a single adult female fish collected in the spring of 2012 tested positive for VHSV by rRT-PCR, and serum from the same fish tested positive by VN and ELISA. These results suggest that VHSV persists and viral transmission may be active in Lake Winnebago even in years following outbreaks and that wild fish may survive VHSV infection and maintain detectable antibody titers while harboring viral RNA. Influxes of immunologically naive juvenile fish through recruitment may reduce herd immunity, allow VHSV to persist, and drive superannual cycles of transmission that may sporadically manifest as fish kills.
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Affiliation(s)
- Anna Wilson-Rothering
- Wisconsin Veterinary Diagnostic Laboratory, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Susan Marcquenski
- Wisconsin Department of Natural Resources Bureau of Fisheries Management, Madison, Wisconsin, USA
| | - Ryan Koenigs
- Wisconsin Department of Natural Resources Bureau of Fisheries Management, Oshkosh, Wisconsin, USA
| | - Ronald Bruch
- Wisconsin Department of Natural Resources Bureau of Fisheries Management, Madison, Wisconsin, USA
| | - Kendall Kamke
- Wisconsin Department of Natural Resources Bureau of Fisheries Management, Oshkosh, Wisconsin, USA
| | - Daniel Isermann
- U.S. Geological Survey, Wisconsin Cooperative Fishery Research Unit, College of Natural Resources, University of Wisconsin-Stevens Point, Stevens Point, Wisconsin, USA
| | - Andrew Thurman
- Department of Statistics and Actuarial Science, University of Iowa, Iowa City, Iowa, USA
| | - Kathy Toohey-Kurth
- Wisconsin Veterinary Diagnostic Laboratory, University of Wisconsin-Madison, Madison, Wisconsin, USA Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Tony Goldberg
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, Wisconsin, USA
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Stepien CA, Pierce LR, Leaman DW, Niner MD, Shepherd BS. Gene Diversification of an Emerging Pathogen: A Decade of Mutation in a Novel Fish Viral Hemorrhagic Septicemia (VHS) Substrain since Its First Appearance in the Laurentian Great Lakes. PLoS One 2015; 10:e0135146. [PMID: 26313549 PMCID: PMC4552161 DOI: 10.1371/journal.pone.0135146] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 07/18/2015] [Indexed: 12/30/2022] Open
Abstract
Viral Hemorrhagic Septicemia virus (VHSv) is an RNA rhabdovirus, which causes one of the world's most serious fish diseases, infecting >80 freshwater and marine species across the Northern Hemisphere. A new, novel, and especially virulent substrain—VHSv-IVb—first appeared in the Laurentian Great Lakes about a decade ago, resulting in massive fish kills. It rapidly spread and has genetically diversified. This study analyzes temporal and spatial mutational patterns of VHSv-IVb across the Great Lakes for the novel non-virion (Nv) gene that is unique to this group of novirhabdoviruses, in relation to its glycoprotein (G), phosphoprotein (P), and matrix (M) genes. Results show that the Nv-gene has been evolving the fastest (k = 2.0x10-3 substitutions/site/year), with the G-gene at ~1/7 that rate (k = 2.8x10-4). Most (all but one) of the 12 unique Nv- haplotypes identified encode different amino acids, totaling 26 changes. Among the 12 corresponding G-gene haplotypes, seven vary in amino acids with eight total changes. The P- and M- genes are more evolutionarily conserved, evolving at just ~1/15 (k = 1.2x10-4) of the Nv-gene’s rate. The 12 isolates contained four P-gene haplotypes with two amino acid changes, and six M-gene haplotypes with three amino acid differences. Patterns of evolutionary changes coincided among the genes for some of the isolates, but appeared independent in others. New viral variants were discovered following the large 2006 outbreak; such differentiation may have been in response to fish populations developing resistance, meriting further investigation. Two 2012 variants were isolated by us from central Lake Erie fish that lacked classic VHSv symptoms, having genetically distinctive Nv-, G-, and M-gene sequences (with one of them also differing in its P-gene); they differ from each other by a G-gene amino acid change and also differ from all other isolates by a shared Nv-gene amino acid change. Such rapid evolutionary differentiation may allow new viral variants to evade fish host recognition and immune responses, facilitating long-time persistence along with expansion to new geographic areas.
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Affiliation(s)
- Carol A. Stepien
- Great Lakes Genetics/Genomics Laboratory, Lake Erie Center and Department of Environmental Sciences, The University of Toledo, Toledo, Ohio, 43616, United States of America
- * E-mail:
| | - Lindsey R. Pierce
- Great Lakes Genetics/Genomics Laboratory, Lake Erie Center and Department of Environmental Sciences, The University of Toledo, Toledo, Ohio, 43616, United States of America
| | - Douglas W. Leaman
- Department of Biological Sciences, The University of Toledo, Toledo, Ohio, 43606, United States of America
| | - Megan D. Niner
- Great Lakes Genetics/Genomics Laboratory, Lake Erie Center and Department of Environmental Sciences, The University of Toledo, Toledo, Ohio, 43616, United States of America
| | - Brian S. Shepherd
- ARS/USDA/University of Wisconsin at Milwaukee/School of Freshwater Sciences, Milwaukee, Wisconsin, 53204, United States of America
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25
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High throughput screening of scFv antibodies against viral hemorrhagic septicaemia virus by flow cytometry. J Virol Methods 2015; 219:18-22. [DOI: 10.1016/j.jviromet.2015.03.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Revised: 03/13/2015] [Accepted: 03/13/2015] [Indexed: 11/17/2022]
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Getchell RG, Erkinharju T, Johnson AO, Davis BW, Hatch EE, Cornwell ER, Bowser PR. Goldfish Carassius auratus susceptibility to viral hemorrhagic septicemia virus genotype IVb depends on exposure route. DISEASES OF AQUATIC ORGANISMS 2015; 115:25-36. [PMID: 26119297 PMCID: PMC10958202 DOI: 10.3354/dao02872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We assessed the susceptibility of goldfish Carassius auratus to infection by genotype IVb of the viral hemorrhagic septicemia virus. Goldfish were infected by intraperitoneal injections of 106 plaque-forming units (pfu) fish-1, single bath exposure of 105 pfu ml-1 for 24 h, or consumption of 0.4 g of commercial fish feed soaked in 107 pfu per 8 fish. The mortality rate of intraperitoneal-infected goldfish was 10 to 32%, although the virus was detected by quantitative RT-PCR in 77% (65/84) of the survivors at the end of the 42 d trial, suggesting a carrier state. Severe gross lesions were observed in many of the moribund and dead goldfish such as hemorrhaging in the skin, fin, liver, kidney, brain, intestine, and eye as well as abdominal distension, bilateral exophthalmia, and splenomegaly. There was minimal morbidity or mortality in the immersion, feeding, or control groups.
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Affiliation(s)
- Rodman G. Getchell
- Aquatic Animal Health Program, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, 930 Campus Road, Ithaca, NY 14853, USA
| | - Toni Erkinharju
- Aquatic Animal Health Program, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, 930 Campus Road, Ithaca, NY 14853, USA
- Present address: Faculty of Biosciences, Fisheries and Economics, Norwegian College of Fishery Science, University of Tromsø, Pb 6050 Langnes, 9037 Tromsø, Norway
| | - Anna O. Johnson
- Aquatic Animal Health Program, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, 930 Campus Road, Ithaca, NY 14853, USA
- Present address: Department of Biology, College of Charleston, 66 George Street, Charleston, SC 29424, USA
| | - Benjamin W. Davis
- Aquatic Animal Health Program, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, 930 Campus Road, Ithaca, NY 14853, USA
| | - Emily E. Hatch
- Aquatic Animal Health Program, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, 930 Campus Road, Ithaca, NY 14853, USA
- Present address: Department of Education/Childhood Education, Corning Community College, 1 Academic Drive, Corning, NY 14830, USA
| | - Emily R. Cornwell
- Aquatic Animal Health Program, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, 930 Campus Road, Ithaca, NY 14853, USA
| | - Paul R. Bowser
- Aquatic Animal Health Program, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, 930 Campus Road, Ithaca, NY 14853, USA
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27
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Imanse SM, Cornwell ER, Getchell RG, Kurath G, Bowser PR. In vivo and in vitro phenotypic differences between Great Lakes VHSV genotype IVb isolates with sequence types vcG001 and vcG002. JOURNAL OF GREAT LAKES RESEARCH 2014; 40:879-885. [PMID: 25722533 PMCID: PMC4337033 DOI: 10.1016/j.jglr.2014.08.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Viral hemorrhagic septicemia virus (VHSV) is an aquatic rhabdovirus first recognized in farmed rainbow trout in Denmark. In the past decade, a new genotype of this virus, IVb was discovered in the Laurentian Great Lakes basin and has caused several massive die-offs in some of the 28 species of susceptible North American freshwater fishes. Since its colonization of the Great Lakes, several closely related sequence types within genotype IVb have been reported, the two most common of which are vcG001 and vcG002. These sequence types have different spatial distributions in the Great Lakes. The aim of this study was to determine whether the genotypic differences between representative vcG001 (isolate MI03) and vcG002 (isolate 2010-030 #91) isolates correspond to phenotypic differences in terms of virulence using both an in vitro and in vivo approach. In vitro infection of epithelioma papulosum cyprini (EPC), bluegill fry (BF-2), and Chinook salmon embryo (CHSE) cells demonstrated some differences in onset and rate of growth in EPC and BF-2 cells, without any difference in the quantity of RNA produced. In vivo infection of round gobies (Neogobius melanostomus) via immersion exposure to different concentrations of vcG001 or vcG002 caused a significantly greater mortality in round gobies exposed to 102 plaque forming units ml-1 of vcG001. These experiments suggest that there are phenotypic differences between Great Lakes isolates of VHSV genotype IVb.
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Affiliation(s)
- Sierra M. Imanse
- Aquatic Animal Health Program, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY
| | - Emily R. Cornwell
- Aquatic Animal Health Program, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY
| | - Rodman G. Getchell
- Aquatic Animal Health Program, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY
| | - Gael Kurath
- Western Fisheries Research Center, U.S. Geological Survey, 6505 NE 65 Street, Seattle, WA
| | - Paul R. Bowser
- Aquatic Animal Health Program, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY
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Warg JV, Clement T, Cornwell ER, Cruz A, Getchell RG, Giray C, Goodwin AE, Groocock GH, Faisal M, Kim R, Merry GE, Phelps NBD, Reising MM, Standish I, Zhang Y, Toohey-Kurth K. Detection and surveillance of viral hemorrhagic septicemia virus using real-time RT-PCR. I. Initial comparison of four protocols. DISEASES OF AQUATIC ORGANISMS 2014; 111:1-13. [PMID: 25144112 DOI: 10.3354/dao02753] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Eight laboratories worked collectively to evaluate 4 real-time RT-PCR (rRT-PCR) protocols targeting viral hemorrhagic septicemia virus (VHSV) being considered for deployment to a USA laboratory testing network. The protocols utilized previously published primers and probe sets developed for detection and surveillance of VHSV. All participating laboratories received and followed a standard operating protocol for extraction and for each of the rRT-PCR assays. Performance measures specifically evaluated included limit of detection (defined as the smallest amount of analyte in which 95% of the samples are classified as positive), analytical specificity, assay efficiency across genotype representatives, within- and between-plate variation within a laboratory, and variation between laboratories using the same platform, between platforms, and between software versions. This evaluation clearly demonstrated that the TaqMan®-based assay developed by Jonstrup et al. (2013; J Fish Dis 36:9-23) produced the most consistent analytical performance characteristics for detecting all genotypes of VHSV across the 8 participating laboratories.
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Affiliation(s)
- Janet V Warg
- Diagnostic Virology Laboratory, National Veterinary Services Laboratories, VS, APHIS, USDA, Ames, Iowa 50010, USA
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Gustafson L, Remmenga M, Gardner I, Hartman K, Creekmore L, Goodwin A, Whaley J, Warg J, Gardner S, Scott A. Viral hemorrhagic septicemia IVb status in the United States: Inferences from surveillance activities and regional context. Prev Vet Med 2014; 114:174-87. [DOI: 10.1016/j.prevetmed.2014.02.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 02/20/2014] [Accepted: 02/26/2014] [Indexed: 11/27/2022]
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Millard EV, Brenden TO, LaPatra SE, Marcquenski S, Faisal M. Detection of viral hemorrhagic septicemia virus-IVb antibodies in sera of muskellunge Esox masquinongy using competitive ELISA. DISEASES OF AQUATIC ORGANISMS 2014; 108:187-199. [PMID: 24695232 DOI: 10.3354/dao02712] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A competitive enzyme-linked immunosorbent assay (cELISA) was developed for the detection of antibodies to viral hemorrhagic septicemia virus genotype IVb (VHSV-IVb) in fish sera. Assay conditions were standardized using known negative and positive muskellunge Esox masquinongy. A positive-negative threshold of 14.6% inhibition was established based on analysis of sera of 60 muskellunge with no previous exposure to VHSV-IVb. The cELISA was then used to investigate immune responses of wild muskellunge sampled from 5 water bodies in Michigan and Wisconsin, USA, between 2005 and 2012. Antibodies were detected in fish from Lake St. Clair, Michigan, and Lower Fox River/Green Bay, Wisconsin. Both water systems were considered enzootic for VHSV-IVb. Additionally, antibodies were detected in muskellunge from Thornapple Lake, a Michigan inland lake previously considered negative for VHSV-IVb based on virus isolation methods. Muskellunge populations from Lake Hudson, Michigan, and Butternut Lake, Wisconsin, lacked evidence of an immune response to VHSV-IVb. When results of the cELISA were compared to the 50% plaque neutralization test for several groups of fish, there was 78.4% agreement between the tests for antibody presence. The cELISA is a rapid and efficient test for the detection of binding antibodies to VHSV-IVb and will be a useful non-lethal tool for monitoring the spread of this serious pathogen.
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Affiliation(s)
- Elena V Millard
- Department of Pathobiology and Diagnostic Investigation, Michigan State University, East Lansing, Michigan 48824, USA
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31
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Development and evaluation of a blocking enzyme-linked immunosorbent assay and virus neutralization assay to detect antibodies to viral hemorrhagic septicemia virus. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2014; 21:435-42. [PMID: 24429071 DOI: 10.1128/cvi.00675-13] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Viral hemorrhagic septicemia virus (VHSV) is a target of surveillance by many state and federal agencies in the United States. Currently, the detection of VHSV relies on virus isolation, which is lethal to fish and indicates only the current infection status. A serological method is required to ascertain prior exposure. Here, we report two serologic tests for VHSV that are nonlethal, rapid, and species independent, a virus neutralization (VN) assay and a blocking enzyme-linked immunosorbent assay (ELISA). The results show that the VN assay had a specificity of 100% and sensitivity of 42.9%; the anti-nucleocapsid-blocking ELISA detected nonneutralizing VHSV antibodies at a specificity of 88.2% and a sensitivity of 96.4%. The VN assay and ELISA are valuable tools for assessing exposure to VHSV.
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32
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Emmenegger EJ, Moon CH, Hershberger PK, Kurath G. Virulence of viral hemorrhagic septicemia virus (VHSV) genotypes Ia, IVa, IVb, and IVc in five fish species. DISEASES OF AQUATIC ORGANISMS 2013; 107:99-111. [PMID: 24334352 DOI: 10.3354/dao02671] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The susceptibility of yellow perch Perca flavescens, rainbow trout Oncorhynchus mykiss, Chinook salmon O. tshawytscha, koi Cyprinus carpio koi, and Pacific herring Clupea pallasii to 4 strains of viral hemorrhagic septicemia virus (VHSV) was assessed. Fish were challenged via intraperitoneal injection with high (1 × 106 plaque-forming units, PFU) and low (1 × 103 PFU) doses of a European strain (genotype Ia), and North American strains from the West coast (genotype IVa), Great Lakes (genotype IVb), and the East coast (genotype IVc). Pacific herring were exposed to the same VHSV strains, but at a single dose of 5 × 103 PFU ml-1 by immersion in static seawater. Overall, yellow perch were the most susceptible, with cumulative percent mortality (CPM) ranging from 84 to 100%, and 30 to 93% in fish injected with high or low doses of virus, respectively. Rainbow trout and Chinook salmon experienced higher mortalities (47 to 98% CPM) after exposure to strain Ia than to the other virus genotypes. Pacific herring were most susceptible to strain IVa with an average CPM of 80% and moderately susceptible (42 to 52% CPM) to the other genotypes. Koi had very low susceptibility (≤5.0% CPM) to all 4 VHSV strains. Fish tested at 7 d post challenge were positive for all virus strains, with yellow perch having the highest prevalence and concentrations of virus, and koi the lowest. While genotype Ia had higher virulence in salmonid species, there was little difference in virulence or host-specificity between isolates from subtypes IVa, IVb, and IVc.
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Affiliation(s)
- Eveline J Emmenegger
- US Geological Survey, Western Fisheries Research Center, 6505 NE 65th St. Seattle, Washington 98115, USA
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33
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Getchell RG, Cornwell ER, Groocock GH, Wong PT, Coffee LL, Wooster GA, Bowser PR. Experimental transmission of VHSV genotype IVb by predation. JOURNAL OF AQUATIC ANIMAL HEALTH 2013; 25:221-229. [PMID: 23998650 DOI: 10.1080/08997659.2013.811126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Preliminary surveillance of wild baitfish during the 2006 viral hemorrhagic septicemia virus genotype IVb (VHSV IVb) outbreaks indicated Emerald Shiners Notropis atherinoides and Bluntnose Minnow Pimephales notatus were infected with high levels of VHSV without showing clinical signs of disease. The movement and use of baitfish was recognized as the most probable vector for the introduction of VHSV to inland waters, such as Conesus Lake and Skaneateles Lake in New York, Budd Lake in Michigan, and Little Lake Butte des Morts and Lake Winnebago in Wisconsin. While numerous government agencies implemented restrictions to stop the movement of potentially infected baitfish into new waters and prevent the spread of VHSV IVb, until now, studies to investigate whether these initial introductions were by an oral route of infection have not occurred. Our studies identified infected Fathead Minnow Pimephales promelas as suitable vectors for transmitting VHSV IVb when fed to Tiger Muskellunge ( ♂ Northern Pike Esox lucius × ♀ Muskellunge Esox masquinongy) during laboratory trials. Six of 16 Tiger Muskellunge were infected with VHSV IVb after consumption of infected Fathead Minnows when assayed with quantitative reverse transcriptase polymerase chain reaction and viral isolation in cell culture. Weekly sampling of water and feces from these Tiger Muskellunge individually reared showed intermittent shedding of VHSV IVb. Those exposed to similarly VHSV IVb-inoculated fathead minnows by cohabitation only became infected in 1 case out of 16. A similar trial of 12 Tiger Muskellunge fed Round Goby Neogobius melanostomus that survived a VHSV IVb immersion challenge did not result in infection. Overall, our findings imply that consumption of infected wild baitfish may be a risk factor for introduction of VHSV.
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Affiliation(s)
- Rodman G Getchell
- a Aquatic Animal Health Program, Department of Microbiology and Immunology, College of Veterinary Medicine , Cornell University, Upper Tower Road , Ithaca , New York , 14853 , USA
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Ito T, Olesen NJ. Susceptibility of various Japanese freshwater fish species to an isolate of viral haemorrhagic septicaemia virus (VHSV) genotype IVb. DISEASES OF AQUATIC ORGANISMS 2013; 107:1-8. [PMID: 24270018 DOI: 10.3354/dao02667] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Genotype IVb of viral haemorrhagic septicaemia virus (VHSV) was isolated for the first time in the Great Lakes basin in 2003, where it spread and caused mass mortalities in several wild fish species throughout the basin. In order to prevent further spreading of the disease and to assess risks of new genotypes invading new watersheds, basic microbiological information such as pathogenicity studies are essential. In this study, experimental infections were conducted on 7 indigenous freshwater fish species from Japan by immersion with a VHSV genotype IVb isolate. In Expt 1, cumulative mortalities in bluegill Lepomis macrochirus used as positive controls, Japanese fluvial sculpin Cottus pollux, and iwana Salvelinus leucomaenis pluvius were 50, 80 and 0%, respectively. In Expt 2, cumulative mortalities of 100, 100 and 10% were observed in Japanese fluvial sculpin C. pollux, Japanese rice fish Oryzias latipes and yoshinobori Rhinogobius sp., respectively. No mortality was observed in honmoroko Gnathopogon caerulescens, akaza Liobagrus reini or Japanese striped loach Cobitis biwae. VHSV was detected by RT-PCR from samples of kidney, spleen, and brain from all dead fish, and virus re-isolation by cell culture was successful from all dead fish. We detected the virus in the brain from a few surviving bluegill 50 d post exposure by both cell culture and RT-PCR. These results revealed that VHSV IVb could become a serious threat to wild freshwater fish species in Japan, and that some surviving fish might become healthy carriers of the virus.
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Affiliation(s)
- Takafumi Ito
- Tamaki Laboratory, Aquatic Animal Health Division, National Research Institute of Aquaculture, Fisheries Research Agency, 224-1 Hiruta, Tamaki, Mie 519-0423, Japan
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Olson W, Emmenegger E, Glenn J, Winton J, Goetz F. Comparative susceptibility among three stocks of yellow perch, Perca flavescens (Mitchill), to viral haemorrhagic septicaemia virus strain IVb from the Great Lakes. JOURNAL OF FISH DISEASES 2013; 36:711-719. [PMID: 23305522 DOI: 10.1111/jfd.12068] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Revised: 11/08/2012] [Accepted: 11/11/2012] [Indexed: 06/01/2023]
Abstract
The Great Lakes strain of viral haemorrhagic septicaemia virus IVb (VHSV-IVb) is capable of infecting a wide number of naive species and has been associated with large fish kills in the Midwestern United States since its discovery in 2005. The yellow perch, Perca flavescens (Mitchill), a freshwater species commonly found throughout inland waters of the United States and prized for its high value in sport and commercial fisheries, is a species documented in several fish kills affiliated with VHS. In the present study, differences in survival after infection with VHSV IVb were observed among juvenile fish from three yellow perch broodstocks that were originally derived from distinct wild populations, suggesting innate differences in susceptibility due to genetic variance. While all three stocks were susceptible upon waterborne exposure to VHS virus infection, fish derived from the Midwest (Lake Winnebago, WI) showed significantly lower cumulative % survival compared with two perch stocks derived from the East Coast (Perquimans River, NC and Choptank River, MD) of the United States. However, despite differences in apparent susceptibility, clinical signs did not vary between stocks and included moderate-to-severe haemorrhages at the pelvic and pectoral fin bases and exophthalmia. After the 28-day challenge was complete, VHS virus was analysed in subsets of whole fish that had either survived or succumbed to the infection using both plaque assay and quantitative PCR methodologies. A direct correlation was identified between the two methods, suggesting the potential for both methods to be used to detect virus in a research setting.
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Affiliation(s)
- W Olson
- School of Freshwater Sciences, University of Wisconsin, Milwaukee, WI, USA
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36
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Garver KA, Traxler GS, Hawley LM, Richard J, Ross JP, Lovy J. Molecular epidemiology of viral haemorrhagic septicaemia virus (VHSV) in British Columbia, Canada, reveals transmission from wild to farmed fish. DISEASES OF AQUATIC ORGANISMS 2013; 104:93-104. [PMID: 23709462 DOI: 10.3354/dao02588] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Viral haemorrhagic septicaemia virus (VHSV) is a fish pathogen found throughout the Northern Hemisphere and is capable of infecting and causing mortality in numerous marine and freshwater hosts. In the coastal waters of British Columbia, Canada, the virus has been detected for 20 yr with many occurrences of mass mortalities among populations of Pacific herring Clupea pallasii (Valenciennes) and sardine Sardinops sagax as well as detections among cultured Atlantic Salmo salar and Chinook Oncorhynchus tshawytscha salmon. We compared nucleotide sequence of the full glycoprotein (G) gene coding region (1524 nt) of 63 VHSV isolates sampled during its recorded presence from 1993 to 2011 from 6 species and a total of 29 sites. Phylogenetic analysis showed that all isolates fell into sub-lineage IVa within the major VHSV genetic group IV. Of the 63 virus isolates, there were 42 unique sequences, each of which was ephemeral, being repeatedly detected at most only 1 yr after its initial detection. Multiple sequence types were revealed during single viral outbreak events, and genetic heterogeneity was observed within isolates from individual fish. Moreover, phylogenetic analysis revealed a close genetic linkage between VHSV isolates obtained from pelagic finfish species and farmed salmonids, providing evidence for virus transmission from wild to farmed fish.
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Affiliation(s)
- Kyle A Garver
- Fisheries and Oceans Canada, Pacific Biological Station, 3190 Hammond Bay Road, Nanaimo, British Columbia V9T 6N7, Canada.
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Cornwell ER, Labuda SL, Groocock GH, Getchell RG, Bowser PR. Experimental Infection of Koi Carp with viral hemorrhagic septicemia virus type IVb. JOURNAL OF AQUATIC ANIMAL HEALTH 2013; 25:36-41. [PMID: 23289973 DOI: 10.1080/08997659.2012.732653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Viral hemorrhagic septicemia virus (VHSV) type IVb has a wide host range that includes at least three cyprinid species: Fathead Minnow Pimephales promelas, Emerald Shiner Notropis atherinoides, and Bluntnose Minnow P. notatus. To date, VHSV IVb has only been found in wild fish. However, the possibility of infection in culture facilities remains. Koi Carp Cyprinus carpio are a major ornamental aquaculture species in the United States; however, their potential to become infected with VHSV IVb has not yet been examined. In this study, we exposed Koi to 3 × 10(6) PFU VHSV Great Lakes isolate MI03 by intraperitoneal injection. While we observed low mortality (0-5%), VHSV was isolated in cell culture from the majority of fish up to 28 d postexposure (DPE) and was detected by a quantitative reverse transcription polymerase chain reaction (qRT-PCR) assay up to 90 DPE, when the trial was terminated. The results of this study strongly suggest that Koi are at risk for VHSV infection, although their susceptibility by intraperitoneal injection appears to be low. This study also provides more evidence of the sensitivity of qRT-PCR for detection of VHSV IVb.
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Affiliation(s)
- Emily R Cornwell
- Department of Microbiology and Immunology, Cornell University, UppIthaca, NY, USA.
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Cornwell ER, Bellmund CA, Groocock GH, Wong PT, Hambury KL, Getchell RG, Bowser PR. Fin and gill biopsies are effective nonlethal samples for detection of Viral hemorrhagic septicemia virus genotype IVb. J Vet Diagn Invest 2013; 25:203-9. [DOI: 10.1177/1040638713476865] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Nonlethal sampling is becoming a common method to diagnose fish diseases, especially with the availability of molecular testing. Viral hemorrhagic septicemia virus (VHSV) is a viral pathogen of finfish distributed worldwide. Although VHSV has been known to occur in some parts of the world for decades, a new genotype, IVb, recently emerged in the Laurentian Great Lakes of northeastern North America. Golden shiners ( Notemigonus crysoleucas; Mitchill, 1814) and fathead minnows ( Pimephales promelas; Rafinesque, 1820) were exposed to VHSV-IVb doses between 102 and 106 plaque forming units per fish by intraperitoneal injection at 10°C. Both species experienced significant mortality after exposure, ranging from 38% to 52% in golden shiners and from 35% to 95% in fathead minnows. In golden shiners, a fin or gill sample was somewhat less sensitive at detecting VHSV-IVb by quantitative reverse transcription polymerase chain reaction (qRT-PCR) than a pooled organ sample (consisting of liver, anterior and posterior kidney, spleen, and heart), however the relative sensitivity increased when a fin and gill sample were tested in parallel. In fathead minnows, a fin or gill sample tested alone or in parallel was relatively more sensitive than a pooled organ sample by qRT-PCR. Specificity was 100% for all sample types in both species. The results suggest that fin and gill biopsies are useful tools to test for VHSV in live fish.
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Affiliation(s)
- Emily R. Cornwell
- Aquatic Animal Health Program, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY
| | - Chelsea A. Bellmund
- Aquatic Animal Health Program, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY
| | - Geoffrey H. Groocock
- Aquatic Animal Health Program, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY
| | - Po Ting Wong
- Aquatic Animal Health Program, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY
| | - Katherine L. Hambury
- Aquatic Animal Health Program, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY
| | - Rodman G. Getchell
- Aquatic Animal Health Program, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY
| | - Paul R. Bowser
- Aquatic Animal Health Program, Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY
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Bland F, Snow M, Garver KA, Matejusova I. Genotype-specific Taqman® assays for the detection and rapid characterisation of European strains of viral haemorrhagic septicaemia virus. J Virol Methods 2013; 187:209-14. [DOI: 10.1016/j.jviromet.2012.10.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Revised: 09/25/2012] [Accepted: 10/12/2012] [Indexed: 11/29/2022]
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Reichert M, Matras M, Skall HF, Olesen NJ, Kahns S. Trade practices are main factors involved in the transmission of viral haemorrhagic septicaemia. JOURNAL OF FISH DISEASES 2013; 36:103-114. [PMID: 23020691 DOI: 10.1111/jfd.12004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Revised: 07/12/2012] [Accepted: 07/13/2012] [Indexed: 06/01/2023]
Abstract
Viral haemorrhagic septicaemia (VHS), caused by the novirhabdovirus viral haemorrhagic septicaemia virus (VHSV), causes significant economic problems to European rainbow trout, Oncorhynchus mykiss (Walbaum), production. The virus isolates can be divided into four distinct genotypes with additional subgroups. The main source of outbreaks in European rainbow trout farming is sublineage Ia isolates. Recently, this group of isolates has been further subdivided in to two subclades of which the Ia-2 consists of isolates occurring mainly in Continental Europe outside of Denmark. In this study, we sequenced the full-length G-gene sequences of 24 VHSV isolates that caused VHS outbreaks in Polish trout farms between 2005 and 2009. All these isolates were identified as genotype Ia-2; they divided however into two genetically distinct subgroups, that we name Pol I and Pol II. The Pol I isolates mainly caused outbreaks in the southern part of Poland, while Pol II isolates predominantly were sampled in the north of Poland, although it seems that they have been transmitted to other parts of the country. Molecular epidemiology was used for characterization of transmission pathways. This study shows that a main cause of virus transmission appears to be movement of fish. At least in Polish circumstances trading practices appear to have significant impact on spreading of VHSV infection.
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Affiliation(s)
- M Reichert
- Department of Pathology, National Veterinary Research Institute, Pulawy, Poland.
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41
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Pham PH, Lumsden JS, Tafalla C, Dixon B, Bols NC. Differential effects of viral hemorrhagic septicaemia virus (VHSV) genotypes IVa and IVb on gill epithelial and spleen macrophage cell lines from rainbow trout (Oncorhynchus mykiss). FISH & SHELLFISH IMMUNOLOGY 2013; 34:632-640. [PMID: 23257204 DOI: 10.1016/j.fsi.2012.12.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Revised: 12/05/2012] [Accepted: 12/07/2012] [Indexed: 06/01/2023]
Abstract
The two most prominent genotypes of viral hemorrhagic septicemia virus (VHSV) are -I in the Northeastern Atlantic region and -IV in North America, but much more is known about the cellular pathogenesis of genotype -I than -IV. VHSV genotype -IV is divided into -IVa from the Northeast Pacific Ocean and -IVb from the Great Lakes and both of which are less virulent to rainbow trout than genotype -I. In this work, infections of VHSV-IVa and -IVb have been studied in two rainbow trout cell lines, RTgill-W1 from the gill epithelium, and RTS11 from spleen macrophages. RTgill-W1 produced infectious progeny of both VHSV-IVa and -IVb. However, VHSV-IVa was more infectious than -IVb toward RTgill-W1: -IVa caused cytopathic effect (CPE) at a lower viral titre, elicited CPE earlier, and yielded higher titres. By contrast, no CPE and no increase in viral titre were observed in RTS11 cultures infected with either genotype. Yet in RTS11 all six VHSV genes were expressed and antiviral genes, Mx2 and Mx3, were up regulated by VHSV-IVb and -IVa. However, replication appeared to terminate at the translational stage as viral N protein, presumably the most abundant of the VSHV proteins, was not detected in either infected RTS11 cultures. In RTgill-W1, Mx2 and Mx3 were up regulated to similar levels by both viral genotypes, while VHSV-IVa induced higher levels of IFN1, IFN2 and LGP2A than VHSV-IVb.
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Affiliation(s)
- P H Pham
- Department of Biology, University of Waterloo, Waterloo, Ontario, Canada
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42
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Jonstrup SP, Kahns S, Skall HF, Boutrup TS, Olesen NJ. Development and validation of a novel Taqman-based real-time RT-PCR assay suitable for demonstrating freedom from viral haemorrhagic septicaemia virus. JOURNAL OF FISH DISEASES 2013; 36:9-23. [PMID: 23016520 DOI: 10.1111/j.1365-2761.2012.01416.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Revised: 02/07/2012] [Accepted: 03/08/2012] [Indexed: 06/01/2023]
Abstract
Viral haemorrhagic septicaemia (VHS) is a serious disease in several fish species. VHS is caused by the rhabdovirus viral haemorrhagic septicaemia virus (VHSV). To prevent spreading of the pathogen, it is important to use a fast, robust, sensitive and specific diagnostic tool to identify the infected fish. Traditional diagnosis based on isolation in cell culture followed by identification using, for example, ELISA is sensitive and specific but slow. By switching to RT-PCR for surveillance and diagnosis of VHS the time needed before a correct diagnosis can be given will be considerably shortened and the need for maintaining expensive cell culture facilities reduced. Here we present the validation, according to OIE guidelines, of a sensitive and specific Taqman-based real-time RT-PCR. The assay detects all isolates in a panel of 79 VHSV isolates covering all known genotypes and subtypes, with amplification efficiencies of approximately 100%. The analytical and diagnostic specificity of the real-time RT-PCR is close to 1, and the analytical and diagnostic sensitivity is comparable with traditional cell-based methods. In conclusion, the presented real-time RT-PCR assay has the necessary qualities to be used as a VHSV surveillance tool on par with cell culture assays.
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Affiliation(s)
- S P Jonstrup
- Section for Fish Diseases, Division of Poultry, Fish and Fur Animals, National Veterinary Institute, Technical University of Denmark, Århus N, Denmark
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43
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Ito T, Kurita J, Sano M, Skall HF, Lorenzen N, Einer-Jensen K, Olesen NJ. Typing of viral hemorrhagic septicemia virus by monoclonal antibodies. J Gen Virol 2012; 93:2546-2557. [PMID: 22971820 DOI: 10.1099/vir.0.043091-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Seven mAbs with specific reaction patterns against each of the four genotypes and eight subtypes of viral hemorrhagic septicemia virus (VHSV) were produced, aiming to establish an immunoassay for typing VHSV isolates according to their genotype. Among the mAbs, VHS-1.24 reacted with all genotypes except genotype Ie, whilst mAb VHS-9.23 reacted with all genotypes except genotype III. mAb VHS-3.80 reacted with genotypes Ib, Ic, Id and II. mAb VHS-7.57 reacted with genotypes II and IVa, and mAb VHS-5.18 with genotype Ib only. Interestingly, mAb VHS-3.75 reacted with all of the genotype III isolates except a rainbow trout-pathogenic isolate from the west coast of Norway, and reacted in addition with the IVb isolate, CA-NB00-01, from the east coast of the USA. Finally, mAb VHS-1.88 reacted with all genotype IVb isolates from the Great Lakes, but not with CA-NB00-01. In conclusion, we can distinguish between all four genotypes and between five of eight subtypes of VHSV by testing isolates in immunoassay using a panel of nine mAbs. By Western blotting and transfection of cell cultures, it was shown that mAb VHS-1.24 recognized an epitope on the viral phosphoprotein (P), whilst all others recognized antigenic determinants on the nucleoprotein (N). From amino acid alignments of the various genotypes and subtypes of VHSV isolates, it was possible to determine the epitope specificity of mAb VHS-1.24 to be aa 32-34 in the P-protein; the specificities of mAbs VHS-3.80, VHS-7.57 and VHS-3.75 were found to be aa 43 and 45-48, aa 117 and 121, and aa 103, 118 and 121 of the N-protein, respectively.
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Affiliation(s)
- Takafumi Ito
- Tamaki Station, Aquatic Animal Health Division, National Research Institute of Aquaculture, Fisheries Research Agency, 224-1 Hiruta, Tamaki, Mie 519-0423, Japan
| | - Jun Kurita
- Tamaki Station, Aquatic Animal Health Division, National Research Institute of Aquaculture, Fisheries Research Agency, 224-1 Hiruta, Tamaki, Mie 519-0423, Japan
| | - Motohiko Sano
- Aquatic Animal Health Division, National Research Institute of Aquaculture, Fisheries Research Agency, Minami-Ise, Mie 516-0193, Japan
| | - Helle Frank Skall
- National Veterinary Institute, Technical University of Denmark, Hangøvej 2, DK-8200 Århus N, Denmark
| | - Niels Lorenzen
- National Veterinary Institute, Technical University of Denmark, Hangøvej 2, DK-8200 Århus N, Denmark
| | - Katja Einer-Jensen
- National Veterinary Institute, Technical University of Denmark, Hangøvej 2, DK-8200 Århus N, Denmark
| | - Niels Jørgen Olesen
- National Veterinary Institute, Technical University of Denmark, Hangøvej 2, DK-8200 Århus N, Denmark
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44
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Kibenge FS, Godoy MG, Fast M, Workenhe S, Kibenge MJ. Countermeasures against viral diseases of farmed fish. Antiviral Res 2012; 95:257-81. [DOI: 10.1016/j.antiviral.2012.06.003] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Revised: 06/01/2012] [Accepted: 06/09/2012] [Indexed: 12/24/2022]
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Faisal M, Shavalier M, Kim RK, Millard EV, Gunn MR, Winters AD, Schulz CA, Eissa A, Thomas MV, Wolgamood M, Whelan GE, Winton J. Spread of the emerging viral hemorrhagic septicemia virus strain, genotype IVb, in Michigan, USA. Viruses 2012; 4:734-60. [PMID: 22754647 PMCID: PMC3386630 DOI: 10.3390/v4050734] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2012] [Revised: 04/11/2012] [Accepted: 04/13/2012] [Indexed: 11/16/2022] Open
Abstract
In 2003, viral hemorrhagic septicemia virus (VHSV) emerged in the Laurentian Great Lakes causing serious losses in a number of ecologically and recreationally important fish species. Within six years, despite concerted managerial preventive measures, the virus spread into the five Great Lakes and to a number of inland waterbodies. In response to this emerging threat, cooperative efforts between the Michigan Department of Natural Resources (MI DNR), the Michigan State University Aquatic Animal Health Laboratory (MSU-AAHL), and the United States Department of Agriculture-Animal and Plant Health Inspection Services (USDA-APHIS) were focused on performing a series of general and VHSV-targeted surveillances to determine the extent of virus trafficking in the State of Michigan. Herein we describe six years (2005-2010) of testing, covering hundreds of sites throughout Michigan's Upper and Lower Peninsulas. A total of 96,228 fish representing 73 species were checked for lesions suggestive of VHSV and their internal organs tested for the presence of VHSV using susceptible cell lines. Of the 1,823 cases tested, 30 cases from 19 fish species tested positive for VHSV by tissue culture and were confirmed by reverse transcriptase polymerase chain reaction (RT-PCR). Gene sequence analyses of all VHSV isolates retrieved in Michigan demonstrated that they belong to the emerging sublineage "b" of the North American VHSV genotype IV. These findings underscore the complexity of VHSV ecology in the Great Lakes basin and the critical need for rigorous legislation and regulatory guidelines in order to reduce the virus spread within and outside of the Laurentian Great Lakes watershed.
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Affiliation(s)
- Mohamed Faisal
- Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA; (M.S.); (R.K.K.); (E.V.M.); (M.R.G.)
- Department of Fisheries and Wildlife, College of Agriculture and Natural Resources, Michigan State University, East Lansing, MI 48824, USA; (A.D.W.); (C.A.S.)
- Author to whom correspondence should be addressed; ; Tel.: +1-517-884-2019; Fax: +1-517-432-2310
| | - Megan Shavalier
- Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA; (M.S.); (R.K.K.); (E.V.M.); (M.R.G.)
| | - Robert K. Kim
- Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA; (M.S.); (R.K.K.); (E.V.M.); (M.R.G.)
| | - Elena V. Millard
- Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA; (M.S.); (R.K.K.); (E.V.M.); (M.R.G.)
| | - Michelle R. Gunn
- Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA; (M.S.); (R.K.K.); (E.V.M.); (M.R.G.)
| | - Andrew D. Winters
- Department of Fisheries and Wildlife, College of Agriculture and Natural Resources, Michigan State University, East Lansing, MI 48824, USA; (A.D.W.); (C.A.S.)
| | - Carolyn A. Schulz
- Department of Fisheries and Wildlife, College of Agriculture and Natural Resources, Michigan State University, East Lansing, MI 48824, USA; (A.D.W.); (C.A.S.)
| | - Alaa Eissa
- Department of Fish Diseases and Management, Cairo University, Cairo, Egypt;
| | - Michael V. Thomas
- Michigan Department of Natural Resources, State of Michigan Government, Lansing, MI 48909, USA; (M.V.T.); (M.W.); (G.E.W.)
| | - Martha Wolgamood
- Michigan Department of Natural Resources, State of Michigan Government, Lansing, MI 48909, USA; (M.V.T.); (M.W.); (G.E.W.)
| | - Gary E. Whelan
- Michigan Department of Natural Resources, State of Michigan Government, Lansing, MI 48909, USA; (M.V.T.); (M.W.); (G.E.W.)
| | - James Winton
- United States Geological Survey-Western Fisheries Research Center, Seattle, WA 98115, USA;
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46
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Hansen JD, Woodson JC, Hershberger PK, Grady C, Gregg JL, Purcell MK. Induction of anti-viral genes during acute infection with Viral hemorrhagic septicemia virus (VHSV) genogroup IVa in Pacific herring (Clupea pallasii). FISH & SHELLFISH IMMUNOLOGY 2012; 32:259-267. [PMID: 22155011 DOI: 10.1016/j.fsi.2011.11.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2011] [Revised: 11/10/2011] [Accepted: 11/11/2011] [Indexed: 05/31/2023]
Abstract
Infection with the aquatic rhabdovirus Viral hemorrhagic septicemia virus (VHSV) genogroup IVa results in high mortality in Pacific herring (Clupea pallasii) and is hypothesized to be a potential limiting factor for herring recovery. To investigate anti-viral immunity in the Pacific herring, four immune response genes were identified: the myxovirus resistance (Clpa-Mx), a major histocompatibility complex IB (named Clpa-UAA.001), the inducible immunoproteosome subunit 9 (Clpa-PSMB9) and the neutrophil chemotactic factor (Clpa-LECT2). Reverse transcriptase quantitative PCR (RT-qPCR) assays were developed based on these gene sequences to investigate the host immune response to acute VHSV infection following both injection and immersion challenge. Virus levels were measured by both plaque assay and RT-qPCR and peaked at day 6 during the 10-day exposure period for both groups of fish. The interferon stimulated genes (Clpa-Mx, -UAA.001, and -PSMB9) were significantly up-regulated in response to VHSV infection at both 6 and 10 days post-infection in both spleen and fin. Results from this study indicate that Pacific herring mount a robust, early antiviral response in both fin and spleen tissues. The immunological tools developed in this study will be useful for future studies to investigate antiviral immunity in Pacific herring.
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Affiliation(s)
- John D Hansen
- US Geological Survey-Western Fisheries Research Center, 6505 NE 65th Street, Seattle, WA 98115, USA
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47
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Cornwell ER, Eckerlin GE, Getchell RG, Groocock GH, Thompson TM, Batts WN, Casey RN, Kurath G, Winton JR, Bowser PR, Bain MB, Casey JW. Detection of viral hemorrhagic septicemia virus by quantitative reverse transcription polymerase chain reaction from two fish species at two sites in Lake Superior. JOURNAL OF AQUATIC ANIMAL HEALTH 2011; 23:207-217. [PMID: 22372249 DOI: 10.1080/08997659.2011.644411] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Viral hemorrhagic septicemia virus (VHSV) was first detected in the Laurentian Great Lakes in 2005 during a mortality event in the Bay of Quinte, Lake Ontario. Subsequent analysis of archived samples determined that the first known isolation of VHSV in the Laurentian Great Lakes was from a muskellunge Esox masquinongy collected in Lake St. Clair in 2003. By the end of 2008, mortality events and viral isolations had occurred in all of the Laurentian Great Lakes except Lake Superior. In 2009, a focused disease surveillance program was designed to determine whether VHSV was also present in Lake Superior. In this survey, 874 fish from 7 sites along the U.S. shoreline of Lake Superior were collected during June 2009. Collections were focused on nearshore species known to be susceptible to VHSV. All fish were dissected individually by using aseptic techniques and were tested for the presence of VHSV genetic material by use of a quantitative reverse transcription (qRT) polymerase chain reaction (PCR) targeting the viral nucleoprotein gene. Seventeen fish from two host species at two different sites tested positive at low levels for VHSV. All attempts to isolate virus in cell culture were unsuccessful. However, the presence of viral RNA was confirmed independently in five fish by using a nested PCR that targeted the glycoprotein (G) gene. Partial G gene sequences obtained from three fish were identical to the corresponding sequence from the original 2003 VHSV isolate (MI03) from muskellunge. These detections represent the earliest evidence for the presence of VHSV in Lake Superior and illustrate the utility of the highly sensitive qRT-PCR assay for disease surveillance in aquatic animals.
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Affiliation(s)
- Emily R Cornwell
- Aquatic Animal Health Program, Department of Microbiology and Immunology, College of Veterinary Medicine, Upper Tower Road, Cornell University, Ithaca, New York 14853, USA.
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48
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Weeks C, Kim R, Wolgamod M, Whelan G, Faisal M. Experimental infection studies demonstrate the high susceptibility of the salmonid, lake herring, Coregonus artedi (Le Sueur), to the Great Lakes strain of viral haemorrhagic septicaemia virus (genotype IVb). JOURNAL OF FISH DISEASES 2011; 34:887-891. [PMID: 21988361 DOI: 10.1111/j.1365-2761.2011.01301.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Affiliation(s)
- C Weeks
- Department of Fisheries and Wildlife, College of Agriculture and Natural Resources, Michigan State University, East Lansing, MI 48827, USA
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49
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Bain MB, Cangelosi A, Eder TA. Monitoring microbes in the Great Lakes. ENVIRONMENTAL MONITORING AND ASSESSMENT 2011; 182:431-442. [PMID: 21336487 DOI: 10.1007/s10661-011-1887-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Accepted: 01/25/2011] [Indexed: 05/30/2023]
Abstract
Great Lakes environmental agencies want to build the capacity to understand microbe threats and develop responses and mitigation plans in advance of crises such as large fish kills. We developed a collaborative plan for monitoring microbes across the Great Lakes of North America to meet practical needs with the latest science and testing technology. The goal was to build understanding of harmful microbes and be rapid, relevant, and robust in addressing threats. The program was oriented for adaptability to changing threats and will target areas of human activity, especially shipping ports and invasion hotspots. Sampling will be aimed at fish and water with application of molecular testing procedures that will allow rapid, efficient, and very sensitive detection of microbes. Compared to other programs with similar aims, our agenda is broader in scope, focuses on building knowledge, uses a representative sampling design, and will provide findings for proactive management and response planning. The reliance on molecular testing procedures, sample archiving, and rapid and broadly distributed results distinguishes our approach from the other similar programs. Fitting microbe monitoring into the Great Lakes environmental management agenda is expected to add an important new dimension to ecosystem monitoring and yield new knowledge of importance for management.
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Affiliation(s)
- Mark B Bain
- Department of Natural Resources, Fernow Hall, Cornell University, Ithaca, NY 14853, USA.
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Thompson TM, Batts WN, Faisal M, Bowser P, Casey JW, Phillips K, Garver KA, Winton J, Kurath G. Emergence of Viral hemorrhagic septicemia virus in the North American Great Lakes region is associated with low viral genetic diversity. DISEASES OF AQUATIC ORGANISMS 2011; 96:29-43. [PMID: 21991663 DOI: 10.3354/dao02362] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Viral hemorrhagic septicemia virus (VHSV) is a fish rhabdovirus that causes disease in a broad range of marine and freshwater hosts. The known geographic range includes the Northern Atlantic and Pacific Oceans, and recently it has invaded the Great Lakes region of North America. The goal of this work was to characterize genetic diversity of Great Lakes VHSV isolates at the early stage of this viral emergence by comparing a partial glycoprotein (G) gene sequence (669 nt) of 108 isolates collected from 2003 to 2009 from 31 species and at 37 sites. Phylogenetic analysis showed that all isolates fell into sub-lineage IVb within the major VHSV genetic group IV. Among these 108 isolates, genetic diversity was low, with a maximum of 1.05% within the 669 nt region. There were 11 unique sequences, designated vcG001 to vcG011. Two dominant sequence types, vcG001 and vcG002, accounted for 90% (97 of 108) of the isolates. The vcG001 isolates were most widespread. We saw no apparent association of sequence type with host or year of isolation, but we did note a spatial pattern, in which vcG002 isolates were more prevalent in the easternmost sub-regions, including inland New York state and the St. Lawrence Seaway. Different sequence types were found among isolates from single disease outbreaks, and mixtures of types were evident within 2 isolates from individual fish. Overall, the genetic diversity of VHSV in the Great Lakes region was found to be extremely low, consistent with an introduction of a new virus into a geographic region with previously naive host populations.
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Affiliation(s)
- Tarin M Thompson
- Western Fisheries Research Center, U.S. Geological Survey, 6505 NE 65th Street, Seattle, Washington 98115, USA
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