fish viral diseases

FISH VIRAL DISEASES

• VIRUS MUST HAVE HOST TO SURVIVE AND REPLICATE

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VIRION

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• SOME HAVE ADDITIONAL LIPID GLYCOPROTEIN COAT–

Size of particles

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VIRUS TYPES

• DNA –

• HERPESVIRUS, IRIDOVIRUSES

• RNA –

• RABDOVORUSES, RETROVORUSES

Effects of Virus Infection

• Histological changes– –

• CPE -

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Host Response/Outcome

• No clinical disease – –

• Clinical disease– – –

MANAGEMENT OPTIONS FOR VIRUSES

• AVOID– –

• VACCINATE

• REDUCE RISKS– –

DNA viruses -Herpes group

• Channel catfish virus (CCV)

• Oncorhynchus masou virus (OMV)

• Walleye herpesvirus (WHV)

DNA - Iridovirus

• Lymphocystis Disease - LDV

• Atlantic Cod Iridovirus

• Viral Erythrocytic Necrosis -VEN

• White Sturgeon Iridovirus

• Viral Erythrocyte Inclusion BodySyndrome - EIBS

Channel catfish virus

• Acute disease • • Clinical signs

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• Diagnosis–

Erythrocytic Inclusions

• VEN– –

• No Red Blood Cells–

• Diagnosis–

EIBS

• First detected spring Chinook salmon LWS hatchery 1982. Hematocrits 2 - 50%

RNA viruses Rhabdoviruses

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• IHNV – Infectious hematopoietic necrosis virus

• VHSV – Viral Hemorrhage septicemia virus

IHNV• Originated as three strains in Western North American

salmonids –

• • Signs

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• Diagnosis– – –

Strains and Virulence

• Single stranded RNA genome that encodes five structural proteins.

• Other factors affecting Virulence– – –

Attenuated Virus

• Nan Scott Lake and Hagerman strains (multiple passages)

• Vaccines– –

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IHNV Control Methods

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VHSV- Viral Haemorrhagic Septicemia Virus

• Described in RBT in Denmark 1949

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VHSV• Signs

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• Diagnosis–

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Marine Reservoir for Pacific Northwest Isolates

• Herring Stocks affected severely – – – –

Birnaviridae - IPNV

• Infectious Pancreatic Necrosis– – –

IPN• Signs

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• Diagnosis– – –

IPNV

• Inactivated by chlorine and iodine

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DI - DEFECTIVE INTERFERING PARTICLES

• GENOME DEFFECTIVE– – – –