Outbreak of VHS in Rainbow Trout
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Questions and Answers

What is the name of the disease caused by VHSV?

  • Inapparent Infections
  • Viral Hemorrhagic Septicemia (correct)
  • Epithelioma papulosum cyprini
  • North American Genotype

What fish species was studied in the Lake St. Clair, Michigan, USA study?

  • Brown Trout
  • Atlantic Salmon
  • Rainbow Trout
  • Muskellunge (correct)

Which of the following is NOT a potential threat associated with VHSV?

  • Introduction of new genotypes to new environments
  • Adaptability to different fish species
  • Effective treatment options available for all genotypes (correct)
  • High pathogenicity in various fish species

What is the significance of the discovery of VHSV Genotype IV in the Great Lakes?

<p>It poses a significant threat to the native fish populations (C)</p> Signup and view all the answers

What is the primary concern regarding the presence of VHSV in Norwegian rainbow trout aquaculture?

<p>It poses a high risk to the Atlantic salmon farming industry (C)</p> Signup and view all the answers

What is the most serious fish disease in continental European aquaculture?

<p>Viral Hemorrhagic Septicemia (D)</p> Signup and view all the answers

Which of the following cell lines was used to study the properties of VHSV?

<p>Epithelioma papulosum cyprini (C)</p> Signup and view all the answers

In what region of the world did an outbreak of VHSV occur in farmed Japanese flounder?

<p>Japan (D)</p> Signup and view all the answers

What is the name of the new contagious strain of VHSV that caused an outbreak in both farmed rainbow trout and experimentally infected Atlantic salmon fingerlings?

<p>Norwegian VHSV Genotype III, NO-2007-50-385 (D)</p> Signup and view all the answers

What is the scientific name for rainbow trout?

<p>Salmo gairdneri Richardson (A)</p> Signup and view all the answers

What is the primary source of infection for the Norwegian VHSV Genotype III, NO-2007-50-385?

<p>It is unknown, but likely originated from wild or farmed marine species. (B)</p> Signup and view all the answers

What is the role of monoclonal antibodies in the context of VHSV research?

<p>They are used to identify and characterize VHSV structural proteins. (A)</p> Signup and view all the answers

What is the significance of the research conducted by Lorenzen, Olesen, and Jørgensen (1993)?

<p>They studied the antibody response of rainbow trout to VHSV proteins. (B)</p> Signup and view all the answers

What is the role of cell lines in the context of VHSV research?

<p>Cell lines are used to grow and study VHSV in the laboratory. (A)</p> Signup and view all the answers

What is the primary research focus of the study by Lumsden et al. (2007)?

<p>The study focuses on the spread of VHSV in freshwater drum. (A)</p> Signup and view all the answers

What is the primary purpose of the study mentioned in the text, as evidenced by the content provided?

<p>To describe the characteristics and origin of a new contagious strain of VHSV (C)</p> Signup and view all the answers

Which genotype of VHSV has been associated with marine species in the North Sea?

<p>Genotype III (B)</p> Signup and view all the answers

What is a common characteristic of VHSV Genotype IV?

<p>Found in both seawater and freshwater species (B)</p> Signup and view all the answers

What method has shown to cause significant mortality in fish infected with marine isolates of VHSV?

<p>Intraperitoneal injection (D)</p> Signup and view all the answers

What was the composition of the pooled tissue samples collected from fish in the study?

<p>Kidney, spleen, heart (B)</p> Signup and view all the answers

In which country was the European Community Reference Laboratory for Fish Diseases located?

<p>Denmark (C)</p> Signup and view all the answers

What type of fish were collected for the analysis of behavioural changes?

<p>Live rainbow trout (D)</p> Signup and view all the answers

Which of the following samples was NOT included in the first sampling for virus evaluation?

<p>Brain (B)</p> Signup and view all the answers

What substance was used for fixing the tissue samples before histopathology?

<p>10% phosphate-buffered formalin (B)</p> Signup and view all the answers

What histopathological finding is characteristic of haemorrhagic lesions observed during necropsy?

<p>Hepatitis with multifocal necrosis (D)</p> Signup and view all the answers

What type of necrosis was particularly evident in the kidney and spleen during the study?

<p>Hemorrhagic necrosis (D)</p> Signup and view all the answers

What was the similarity percentage found in the sequenced PCR product of Isolate NO/650/07 with the VHSV glycoprotein gene?

<p>98% (B)</p> Signup and view all the answers

What major finding was observed in fish that only exhibited nervous signs?

<p>Hemosiderosis in the spleen (A)</p> Signup and view all the answers

What type of cells showed variable degrees of staining for VHSV in the performed IHC?

<p>Endothelial cells and macrophages (C)</p> Signup and view all the answers

What significant cellular changes were found in dead fish during necropsy?

<p>Severe encephalitis with spongy change (B)</p> Signup and view all the answers

What was used to confirm the virological examinations from the second sampling?

<p>CRL in Århus (B)</p> Signup and view all the answers

Which analytical method was performed to determine the phylogenetic relationship of the NO-2007-50-385 isolate?

<p>Full length G-gene sequencing (C)</p> Signup and view all the answers

What organism is primarily affected by viral hemorrhagic septicemia virus?

<p>Rainbow trout (A)</p> Signup and view all the answers

What factor complicates the determination of how the virus outbreak spread to neighbouring farms?

<p>Limited time period of infection (D)</p> Signup and view all the answers

What is suggested about the relationship between virulence of VHSV isolates and their ability to infect cells?

<p>Higher virulence isolates have a greater ability to infect gill epithelial cells (D)</p> Signup and view all the answers

What uncertainty exists regarding the cause of the VHS outbreak?

<p>Whether transmission was direct from a marine source or an adaptation had occurred (A)</p> Signup and view all the answers

Based on the content, which virus is connected to the outbreaks in rainbow trout?

<p>Infectious hematopoietic necrosis virus (A)</p> Signup and view all the answers

Which of the following is a potential source of the VHS outbreak mentioned in the content?

<p>Marine sources (C)</p> Signup and view all the answers

What is the significance of the phylogenetic analyses mentioned in the context?

<p>They reveal genetic consistency among VHSV isolates (D)</p> Signup and view all the answers

Which isolate showed the closest relationship to the NO-2007-50-385 isolate?

<p>DK-4p168 (C)</p> Signup and view all the answers

How many nucleotide differences were found between NO-2007-50-385 and the DK-4p168 isolate?

<p>10 (A)</p> Signup and view all the answers

What was the cumulative mortality rate after the immersion trial of rainbow trout using the NO-2007-50-385 isolate?

<p>70% (D)</p> Signup and view all the answers

What clinical signs were exhibited by moribund infected fish?

<p>Exophthalmia and ascites (B)</p> Signup and view all the answers

Which isolate demonstrated the least similarity to the NO-2007-50-385 isolate?

<p>UK-860/94 (C)</p> Signup and view all the answers

What cumulative mortality was observed in the positive control group of rainbow trout during the i.p. injection trial?

<p>100% (D)</p> Signup and view all the answers

Which statement about the Atlantic salmon in the immersion trial is accurate?

<p>Mortality was not observed. (A)</p> Signup and view all the answers

What was the mortality rate observed in the negative control group of rainbow trout?

<p>3% (A)</p> Signup and view all the answers

Flashcards

Viral Hemorrhagic Septicemia Virus (VHSV)

A type of virus that affects fish, primarily rainbow trout, and is classified into different genotypes based on genetic differences.

VHSV Genotypes

The different genetic variations of VHSV, which can affect different fish species and geographical locations.

VHSV Genotype II

This genotype of VHSV is commonly found in the Baltic Sea affecting herring, sprat, and cod.

VHSV Genotype III

This genotype of VHSV is found in marine species including Norway pout, haddock, whiting, cod, and herring in the North Sea and Skagerrak.

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VHSV Genotype IV

This genotype of VHSV is mainly found in North America and Asia, affecting both saltwater and freshwater species.

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Pathogenicity of VHSV

The ability of VHSV to cause disease and death in fish, which can vary depending on the genotype and the species affected.

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Histopathology

The process of studying the microscopic structure of tissues to understand diseases and how they affect the body.

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Immunohistochemistry

A technique used in histopathology to identify specific proteins or other molecules in tissues using antibodies that bind to these molecules.

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Viral Hemorrhagic Septicemia (VHS)

A type of viral hemorrhagic septicemia (VHS) affecting fish, typically characterized by neurological signs and internal hemorrhages.

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Meningoencephalitis

Inflammation of the meninges, the membranes surrounding the brain and spinal cord.

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Hemosiderosis

The accumulation of blood pigment, hemosiderin, in the spleen.

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Necrosis

Death of cells in a tissue or organ.

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Immunohistochemistry (IHC)

A technique used to identify specific antigens (like viral proteins) in tissues using antibodies.

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Spongy change in the brain

A type of change in the brain tissue where there are small cavities or spaces.

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Neuronal degeneration

Degeneration or breakdown of nerve cells.

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Gliosis

The increase in the number of glial cells, which are support cells in the nervous system.

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Genotype III VHSV

A type of viral hemorrhagic septicemia virus (VHSV) that is highly pathogenic to rainbow trout, capable of causing significant mortality.

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NO-2007-50-385 isolate

A specific isolate of Genotype III VHSV that was identified in Norway in 2007, causing an outbreak in farmed rainbow trout.

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Comparing G-gene sequences

A method for studying virus spread and potential sources by analyzing how similar different virus isolates are to each other. Similar isolates likely came from a common source.

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G-gene

A specific viral gene, often used for comparison to see how closely related different virus strains are.

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Nucleotide differences

A measure of how similar or different two virus strains are based on their genetic sequences. A higher number indicates greater difference, meaning they are likely less related.

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Susceptibility to VHSV

The ability of the fish to resist or overcome the infection by VHSV.

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Infection trial

A study where fish are intentionally exposed to a pathogen to see how they react to it. It helps us understand how dangerous the pathogen is.

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Clinical signs

A sign of disease, like swelling or bleeding, that can be seen in the body of a fish.

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Storfjorden VHS Outbreak

An outbreak of Viral Hemorrhagic Septicemia (VHS) occurred in rainbow trout farms in Storfjorden, Norway. The outbreaks occurred within a short timeframe across several farms owned by the same individual.

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VHS Transmission Source

The study aimed to determine if the VHS virus was introduced to the farms individually or if it spread from a primary infected site to others.

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VHS Marine Adaptation

The researchers investigated if marine VHSV isolates caused the outbreak directly in rainbow trout or if an adaptation to rainbow trout occurred first, leading to disease.

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Marine VHSV and Rainbow Trout

Marine VHSV isolates typically don't cause disease in rainbow trout.

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VHS (Viral Hemorrhagic Septicemia)

Viral Hemorrhagic Septicemia (VHS) is a serious fish disease caused by a virus.

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VHS Transmission Pathways

VHS can be transmitted by a single entry point to a farm and then spread to others, or it can be introduced to multiple farms independently.

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VHS Investigation

The study was conducted to understand the origins and spread of VHS in rainbow trout farms.

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Storfjorden Outbreak Significance

The outbreak in Storfjorden provides valuable insights into the spread and potential adaptation of VHS in rainbow trout.

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What is VHSV?

VHSV (Viral Hemorrhagic Septicemia Virus) is a type of virus that affects fish, causing hemorrhagic septicemia. It has different genotypes based on genetic variations, with Genotype IV being particularly worrisome in the Great Lakes due to its potential for high pathogenicity.

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What is Genotype IV of VHSV?

VHSV Genotype IV is found in North America and Asia, affecting both saltwater and freshwater fish. Its spread to the Great Lakes is a concerning event due to its potential for devastating fish populations.

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What is Pathogenicity?

The ability of a pathogen, like VHSV, to cause disease in a host organism. This is influenced by factors like the genotype of the virus and the susceptibility of the host species.

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How can VHSV affect Salmon Farming?

VHSV, being an RNA virus, is known to adapt quickly to different fish species. This adaptability makes it a potential threat to salmon farming.

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Where was Genotype III found?

VHSV Genotype III has been found in Lake St. Clair, Michigan, USA. This has significant implications because Genotype III is known to affect farmed rainbow trout.

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What happened to rainbow trout during the study?

The study found that VHSV Genotype III caused harm to cultured rainbow trout, highlighting the potential for this virus to impact fish farms.

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What are the implications of VHSV in European aquaculture?

VHSV is a significant threat to European aquaculture, causing a range of problems for fish farms, especially with rainbow trout.

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How can VHSV evolve?

VHSV, being an RNA virus, can evolve quickly and become more pathogenic over time, making it a constant threat to fish populations.

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VHSV Genotype III NO-2007-50-385

A contagious strain of VHSV (Viral Hemorrhagic Septicemia Virus) that causes VHS outbreaks in both farmed and wild rainbow trout, and experimentally infected Atlantic salmon fingerlings.

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Study Notes

Outbreak of Viral Hemorrhagic Septicemia (VHS) in Norwegian Seawater-Farmed Rainbow Trout

  • Viral hemorrhagic septicemia (VHS) is a serious viral disease affecting farmed rainbow trout in Europe.
  • VHS is characterized by hemorrhagic septicemia, and an anaemic and nervous form.
  • The causative agent is VHS virus (VHSV), a member of the Novirhabdovirus genus.
  • VHS is associated with both fresh and saltwater environments.
  • VHS is often chronic, with covert carriers potentially acting as reservoirs.
  • A new strain of VHSV Genotype III was found in Norwegian seawater-farmed rainbow trout.
  • The disease in Norway began in November 2007.
  • The clinical signs included neurological issues and septicemia.
  • The pathogenicity of the virus strain to rainbow trout and Atlantic salmon was examined.
  • The Norwegian isolate caused 52% mortality rate in Atlantic salmon through intraperitoneal injection.
  • The Norwegian VHSV strain is pathogenic to rainbow trout.

Virus Isolation and Identification

  • Tissue samples were collected and submitted to labs for diagnosis.
  • Diagnosis was confirmed through immunohistochemistry and RT-PCR.
  • Virus was isolated and characterized using cell cultures.
  • Immunofluorescence assays were used to confirm VHSV presence in samples.
  • Pooled tissue samples were homogenized to isolate virus.
  • Cell cultures of bluegill and EPC cells were used for viral propagation.
  • The G-gene sequence was analyzed confirming the new VHSV strain is Genotype III.

Pathogenicity Analysis Through Infection Trials

  • Infection trials were conducted on rainbow trout and Atlantic salmon using immersion and intraperitoneal (i.p.) injections.
  • Trials involved testing pathogenicity through both immersion and i.p. injections, using triplicate groups for each.
  • Cumulative mortality of approximately 70% in rainbow trout and 100% in trout through i.p. injection was observed.
  • No mortality was observed in Atlantic salmon subjected to immersion, while i.p. injection resulted in approximately 52% mortality rate.

Epidemiological Analysis of Outbreak

  • The outbreak occurred in Storfjorden, Norway.
  • The outbreak expanded to three surrounding areas.
  • Fish were kept in 20 net pens.
  • Approx. 1.8 million fish were present during the outbreak, weighing 90-440g.
  • The infected fish showed ataxic behavior.
  • Similar pathology and ataxic symptoms were observed in sites located within 5–7 km radius.
  • Fish were from one company .

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PDF Outbreak of Viral Hemorrhagic Septicemia (VHS) in Seawater-Farmed Rainbow Trout in Norway

Description

This quiz explores the outbreak of Viral Hemorrhagic Septicemia (VHS) in Norwegian seawater-farmed rainbow trout. Learn about the characteristics of the VHS virus, its effects on fish populations, and the implications of a new strain discovered in Norway. Test your knowledge on the clinical signs and mortality rates associated with this serious viral disease.

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