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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
– – –
• 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
– – –
• 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
– – – – –
• Diagnosis– – –
IPNV
• Inactivated by chlorine and iodine
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DI - DEFECTIVE INTERFERING PARTICLES
• GENOME DEFFECTIVE– – – –