fish 424: fish health management virology lecture:isav svcv wsiv vhsv

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FISH 424: Fish Health Management Virology Lecture: ISAV SVCV WSIV

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FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV. Infectious Salmon Anemia Virus (ISAV). Hosts and Geographic Range Highly infectious for Atlantic salmon potential asymptomatic carriers of the virus Searun brown trout rainbow trout Atlantic herring. - PowerPoint PPT Presentation

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Page 1: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

FISH 424: Fish Health ManagementVirology Lecture: ISAV

SVCV

WSIV

VHSV

Page 2: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Infectious Salmon Anemia Virus (ISAV)

• Hosts and Geographic Range– Highly infectious for Atlantic

salmon

– potential asymptomatic carriers of the virus

• Searun brown trout

• rainbow trout

• Atlantic herring

Page 3: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Infectious Salmon Anemia (ISAV)

• Viral infection is found in Seawater (Net pens):– Norway (1984)– United Kingdom (1998)– East coast Canada (1998)– East coast United States

(2000)– Chile (1999)

Page 4: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

MAINE

CANADA

Page 5: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV
Page 6: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Infectious Salmon Anemia (ISAV)

• Etiological agent– 1st described as

Hemorrhagic Kidney Syndrome

– member of the orthomyxoviridae family.

– 8 negative strands of RNA enclosed in a lipid envelop

– Virions between 45-140 nm in diameter

Page 7: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Infectious Salmon Anemia (ISAV)

Transmission Electron Micrographs

Page 8: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Infectious Salmon Anemia (ISAV)

• Virulence and Pathology– lethargic, swim near the water

surface

– petechial hemorrhage on skin and fins

– anemia, exophthalmia, ascites

– Pale gills

– hepatomegally, splenomegally

– petechia in the visceral fat

Page 9: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Infectious Salmon Anemia (ISAV)

Page 10: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Infectious Salmon Anemia (ISAV)

• Transmission:– Almost exclusively occurrs

during saltwater stages

– Horizontal (fish to fish contact)

– Coprophagy (feeding on feces)

– Sea lice can transmit ISAv from infected to susceptible fish

– Transfer by contaminated equipment / People / boat traffic / location near fish processing plants

Page 11: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Infectious Salmon Anemia (ISAV)

Alexander G. Murray,*† Ronald J. Smith,* and Ronald M. Stagg**Fisheries Research Services Marine Laboratory, Aberdeen, United Kingdom; and †University of Aberdeen, Aberdeen, United Kingdom

Figure 3. Infection status of areas versus number of well-boat visits. Infection status is 0 for no infection, 1 for suspected infection, and 2 for confirmed infection

Page 12: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Infectious Salmon Anemia (ISAV)

• Diagnosis– Isolation through tissue culture

• SHK-1 and CHSE-214 cells

– IFAT (indirect fluorescent antibody test) on tissue imprints

– RT-PCR (reverse transcriptase poylmerase chain reaction)

                                                                                                                          

      

Page 13: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Infectious Salmon Anemia (ISAV)

• Management– Since the virus is readily transmitted in seawater

– Shown net pen operations within 5-6 km of an infected site can become contaminated

1. culture sites be spaced no less than 5-6 km apart

2. waste water from slaughter and processing facilities should be thoroughly disinfected

3. control of ship and personnel movements among sites

4. compulsory slaughter of infect stocks (eradication)

5. Attempts to require vaccination

Page 14: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Spring Viremia of Carp Virus (SVCV)

• Hosts and Geographic Range– Natural infections have been

recognized in common carp and koi carp (Cyprinus carpio)

– Historically only in Europe and Russia

– Recently, SVC has been reported in koi in the United States for the first time

                                                                                                                                                                                                                                                                                                          

Page 15: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

2. Spring viremia of carp (SVC) was confirmed in ornamental koi carp in Pike County, Missouri on July 13, 2004

Recent News Headlines1. Spring Viremia of Carp virus (SVCv) was recently

identified in a backyard koi and goldfish pond located in Snohomish County, Washington State

3. SVC has previously been reported in Europe, the Middle East and Asia. More recently, it has been reported in North and South America. In the US, SVC outbreaks occurred in North Carolina in 2002 and Washington in June 2004. The virus has also been reported in feral common carp populations in Wisconsin and Illinois. SCV is an OIE notifiable disease.

Page 16: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV
Page 17: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Spring Viremia of Carp Virus

• Etiological agent– Family

Rhabdoviridae

– Bullet shaped morphology

– single-stranded RNA containing 5 genes

Page 18: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Spring Viremia of Carp Virus

• Virulence and Pathology– Darkening of the skin– Distended abdomen– Exopthalmia– Petechial hemorrhage of

the skin, gills, and eyes– Pale gills– Hemorrhage in the swim

bladder– Catarrhal enteritis

Page 19: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Example of exopthalmia and abdominal distention

Clinical signs of disease:•Darkening coloration•Abdominal distension•Exopthalmia

Page 20: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Spring Viremia of Carp Virus

• Virulence and Pathology– virus affects carp at all ages but victims are

mostly young fish.

– Outbreaks depend on the temperature

– High mortality occurs at water temperatures of 10 to 17°C, typically in spring.

– At >20 °C, elevated immune response protects carp from infection and re-infection

Page 21: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Spring Viremia of Carp Virus

• Transmission:– Occurs by horizontal transmission– Excretion of SVCV via feces and urine

from infected fish– Parasitic transfer of SVCV from

diseased to healthy fish– virus could stay infective in the water

for more than 4 wks and 6 wks in the mud

– source of infection may be contaminated equipment

– vertical transmission of SVCV is not an important source of infection

Page 22: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Spring Viremia of Carp Virus

• Diagnosis (Standard Screening Method )– Isolation of SVCV in cell culture

• FHM or EPC tissue culture cells

– Indirect fluorescent antibody test on infected culture cells

or– Enzyme-linked immunosorbent assay (ELISA)or – Neutralization Antibody testor– PCR 

Page 23: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Spring Viremia of Carp Virus

• Management– In rearing facilities with a controlled environment, elevation

of temperature above 20° C can prevent or stop SVC outbreaks

– avoidance of SVCV by using spring or well water

– Eradication of diseased fish

– Control movement of fish• Anglers should not transfer fish or fish parts from one body of water to

another

– Vaccination provides good protection

Page 24: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

White sturgeon iridovirus (WSIV)

• Host and Geographic Range– White Sturgeon– North America

Page 25: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

WSIV History

• Recognized as the most prevalent viral pathogen in White Sturgeon.

• Significant mortality in commercial and conservation aquaculture.

• Northern California commercial sturgeon farms

• Lower Columbia River in Oregon and Washington

• Snake River in Southern Idaho

• Kootenai River in northern Idaho

• British ColumbiaLaPatra et. al. 1994

Page 26: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

WSIV: Manifestation of Disease• Clinical disease can be induced

– Overcrowding, transport, handling, etc.

• Slow chronic wasting syndrome

• Fry and fingerlings (1st year)

• Mortality assumed to be due:

– Anorexia

– Respiratory function

– Osmoregulatory function

– Secondary infection

Page 27: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

WSIV: Clinical Signs of Disease

Darkening Pigmentation Emaciated body

Page 28: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Manifestation of disease

Virus has an affinity for epithelial tissue:

• Skin

• Gill

• Oropharynx

• Olfactory (barbels)Histology shows:•Hypertrophied cells with swollen cytoplasm

Page 29: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

TEM of WSIV infected cells

5000X

Page 30: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

WSIV Morphology

• Icosahedral morphology

• Size (250-300nm)

• Double capsid

• Dense nucleiod center

TEM of WSIV From Kootenai River white sturgeon skin (2004)

Page 31: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

White sturgeon iridovirus (WSIV)

• Transmission– Shown to be transmitted from infected fish to

healthy individuals

– may be endemic in most wild Northwest white sturgeon populations.

– Virus may be vertically transmitted from adult to offspring during spawning.

Page 32: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

White sturgeon iridovirus (WSIV)

• Diagnosis of infection– Difficult to propagate

reliably in tissue culture

– Histology for the detection of large hypertrophied cells within the epithelial tissue of the skin, gills, and barbels.

Page 33: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

White sturgeon iridovirus (WSIV)

• Management– Ideally, avoidance of WSIV by using spring or

well water to rear juvenile sturgeon

– Minimize stress of sturgeon during early life stage

– Control movement of fish

Page 34: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Viral Hemorrhagic Septicemia is 1 of the 7 most important diseases of finfish worldwide and is

listed by the OIE as notifiable

O.I.E. World Organization for Animal Health

Aquatic Animal Health Code 2006

USDA Animal and Plant Health ServiceDesignated at the US Regulatory Authority on

Animal Health

Page 35: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

USDA APHIS Criteria for Diseases/Pathogens of Regulatory Significance

• Causes significant impact on production, wild resources, or human health

• Infectious disease and can be spread by commerce

• Involves host species in interstate or international commerce and be of concern to US trading partners that are free of the disease

• Reliable diagnostic methods available

Page 36: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

USDA APHIS Criteria for Diseases/Pathogens of Regulatory Significance

• Causes significant impact on production, wild resources, or human health• Infectious disease and can be spread by commerce • Involves host species in interstate or international commerce and be of

concern to US trading partners that are free of the disease• Reliable diagnostic methods available

• No human health risk with VHSV• No treatment for VHSV• VHSV has been found ONLY in wild fish in

the Great Lakes Basin

Page 37: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Time Line of VHSV

• 1938- described in RBT in Europe (FW)

• 1963- virus isolated and described (FW)

• 1988- saltwater (SW) VHSV hosts in USA

• 1990 to present- VHSV is found endemic in SW hosts on US East and West Coasts

• 2003-present- Great Lakes VHSV causes mass mortality in a variety of FW hosts, including sport fish important to Idaho

Page 38: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

How bad can it get?

• 2006 Freshwater drum mortality in Lake Erie

• New virus in naïve hosts becomes epizootic

• Millions of pounds of FW drum

• “Windrows of fish” along the beach piled up 10’ wide and 4’ high

Page 39: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Herring mortality B.C. Canada

Page 40: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Herring Rainbow trout Walleye

Page 41: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Disease Signs of VHSV

Hemorrhagic: Causes leaking of blood from vessels especially under the skin and internal organs

Septicemia: Virus in blood and spreads throughout the body in circulation

Pop eye: Caused by pressure of hemorrhage pushing beneath the eye

Page 42: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Host Range of VHSV

• 37 host species FW and SW worldwide

• 28 FW species

• 19 FW species are important to Idaho including rainbow trout, salmon, bass, bluegill, crappie, and perch

• Host range is unheard of for other fish viruses!

Page 43: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Current VHS Outbreaks:2007

Lake Huron

Lake St. Clair

Lake Ontario

St. Lawrence R.

Conesus Lake*

Lake Erie

Budd Lake*

Lake Winnebago*

* Not connected by water – baitfish suspected

Lake Michigan

Page 44: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Current VHS Outbreaks:2007

Lake Huron

Lake St. Clair

Lake Ontario

St. Lawrence R.

Conesus Lake*

Lake Erie

Budd Lake*

Lake Winnebago*

Summer, 2007 NYDEC Surveillance

Lake Michigan

Page 45: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

3.7%-5%

2.1%

Genetic Differences of VHSV Shows an East Coast Origin

Page 46: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

How did VHSV get into the Great Lakes?

Commercial ballast waterNatural movement of infected fishHuman recreational activities

• Sport fishing activities (bait minnows, contaminated fishing equipment, illegal fish stocking)

• Boating

Animal activities (mammals, birds)Basically, vectors are unknown!

Page 47: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Overview

Two genetic types of VHSV correlate West coast and East Coast

VHSV in the Great Lakes likely came from an East Coast host

Conventional cell culture methods detects Great Lakes VHSV strains

VHSV is more stable in freshwater than in sea water.

VHSV lasts up to one month when held at 50ºF

Page 48: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

APHIS Federal Order

• VHSV Federal Order was issued 10/24/2006

• Emergency Action taken to prevent the spread of VHSV

• Must be followed-up by formal rulemaking

Page 49: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Current Provisions Under the Federal Order

• VHS susceptible species are prohibited from moving out of the 8 States and 2 Canadian Provinces bordering the Great Lakes except under certain conditions– Movement to slaughter with adequate disinfection– Movement to a research or diagnostic lab with adequate

disinfection– Movement of live fish testing negative for VHSV by

laboratory assays – Movement of salmonids from Canada that meet

USFWS inspection requirements• Catch-and-Release fishing activities

Page 50: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Implications of VHSV for Idaho

• 20 years surveillance has been negative

in cultured and wild fish

• Sport fishing valued at $ 360 million

• $ 110 million trout culture industry at risk

• ESA-listed anadromous salmon and steelhead cultured in Idaho

• Must prevent VHSV introduction into Idaho

Page 51: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

What has IDFG done to reduce risk?

• Live fish for bait prohibited

• Banned importation of all fish from Great Lakes Basin (GLB)

• Supported APHIS Federal Order

• Banned frozen baitfish from GLB

• Partnering with Idaho Department of Agriculture and trout industry on emergency rule to prevent introduction

Page 52: FISH 424: Fish Health Management Virology Lecture:ISAV SVCV WSIV VHSV

Future needs:

• Risk assessment of potential vectors leading to Biosecurity Plan for Idaho Importations of live fish & eggsPrivate pondsAquatic nuisance speciesAquatic baits other than fish

• Education of anglers to reduce risks• Support research on VHSV susceptibility of Idaho

fish stocks• Idaho Fish Health and Sterility Management

Policy