Aquaculture VirusesWhat a Virus Isn’t • Not a bacterium... • Not independent... • Cannot survive in absence of a living cell within which to replicate... • Antibiotics generally don’t work on them... What Viruses Are... • Infectious agents composed mainly of nucleic acid with a protein coat (capsid) • Visible with electron microscope (10-200 nM) • Carry on normal cell-like function (unless free, then infectious) • In infectious form: no growth; no respiration??? • Can enter living plant, animal or human core and genetic material (DNA/RNA) • Capsid: outer shell of the virus which encloses genetic material (link: chemical structure of capsid helps determine immune response to virus) • capsid is made of many identical individual proteins • protein core under capsid protecting genetic material • sometimes an additional covering (lipid bilayer w/embedded proteins) on outside known as an envelope ( like a baseball) • various forms: rods. cubes.Virus Appearence? • Capsid. filaments. crystals . spheres. Capsid . capsomere: unit/molecule associated with capsid structure . Typical Virus Shapes SPHERES RODS CUBES . More Virus Shapes . . Composition of T-Even Bacteriophage • Capsid: brains of virus. anchor virus to its host . hollow core • Tail: at end of core is a spiked plate carrying 6 slender tail fibers. rod-like structure w/retractible sheath. tightly-wound protein protecting nucleic acids • Body: attached to capsid head. . protein and nucleic acid synthesizing ability to replicate themselves.How do viruses work? • Viruses make use of the host cell’s chemical energy. • each virus attacks a specific type of cell – cold viruses attack cells of the lung – the AIDS virus attacks T4 cells of the immune system – fish viruses are just as specific .. Bacteriophage Attack . or double. disease results! . the virus alters the intracellular environment enough to damage or kill the cell (oops!!) • If enough cells are destroyed.stranded DNA or RNA • Often.Virusal Mechanism • Viruses contain single. g.Role of RNA/DNA • Supplies the codes for building the protein coat (capsid) and for producing enzymes needed to replicate more viruses • Information given so newly-built viruses can lyse cells (e. bacteriophage) • Result: cell destroyed.. . .Bottom Line. .. • All viruses only exist to make more viruses • Most are harmful • Replication = host cell death. The Virus Invasion: Step by step • Phase 1: Attachment of virus to bacteria. releasing hundreds of small viral replicates • This is how it can replicate so quickly! . • Phase 2: injection of DNA or RNA • Phase 3: DNA (RNA) enters the host cell • Phase 4:DNA incorporated (10 minutes) hundreds of virions appear causing the cell to rupture. etc. The Virus Invasion . there may be a 100 or more different viruses which can affect that species alone • Specific: for example.What’s Infected by a Virus? • All living things have some susceptibility to a particular virus • Virus is specific for the organism • Within a species. a virus that only affects one organism (humans and smallpox) • Influenza can infect humans and two animals . singlestranded DNA. plant. singlestranded RNA.Different Types of Viruses • Major classifications: animal. retrovirus • Influenza: SS-RNA . double-stranded RNA. bacterial • Sub-classified by arrangement and type of nucleic acid • Animal virus group: double-stranded DNA. . because a given virus can generate many. the new virus particle might no longer be functional (infectious) • However. • If the mutation is harmful. a small number of non-functional viruses is not important • Mutation is not necessarily damaging to the virus -it can lead to a functional but new strain of virus .Do Viruses ever Change? • Mutations do occur. many copies. which also lines the gastrointestinal and respiratory passageways • skin is tough and stomach acidity acts as a disinfectant • Second Line: after the virus enters the blood and other tissues.Defense Against Viruses • First Line: skin and mucous membrane. white blood cells and related cells (phagocytes) consume them • accumulation of phagocytes in area of infection is known as “puss” . Defense Against Viruses Antibodies attacking chickenpox virus . Defense Against Viruses • • • • Antibodies are the best defense against viruses unfortunately, they are specific in their action chickenpox antibody will only attack a chickenpox virus a particular virus stimulates the production of a particular antibody Defense Against Viral Infection • Animals are protected in several ways: • 1) intracellular: if a particular virus attacks cells, our bodies produce interferons • interferons (alpha, beta or gamma) are proteins which interact with adjacent cells and cause them to become more resistant to infection by the virus • if the resistance is not quite good enough, we become sick Defense Against Viral Infection • 2) immune system (extracellular): kills the virus outside the cell • also kills the infected cells • virus cannot spread • eventually the virus is completely removed and we get better • exception: HIV because it infects cells of the immune system, itself • chemicals/drugs: acyclovir, AZT, HIV protease inhibitor, several fish vaccines available. Major Fish Viruses . Major Viral Infections in Fish • Infectious pancreatic necrosis (IPN) • Viral hemorrhagic septicemia (VHS) • Infectious hematopoetic necrosis (IHN) • • • • • • Channel catfish virus disease (CCVD) Koi Herpes Virs Lymphocytis Cacar virus VNN (Viral Nervous Necrosis) Spring Viraemia of Carp (SVC) . wiped out brook trout in Oregon in 1971-73 • Size: Only 65 nM in diam. smallest of fish viruses .(1) Infectious Pancreatic Necrosis (IPN) • What?: viral infection of salmonids (trout and char) • Time: Acute • Result: high mortality (fry and fingerlings) • Rare in larger fish (good thing!) • History: Isolated in Pacific NW in 1960’s.. ).IPN: general notes • Single capsid shell. icosohedral symmetry. etc. ether. variable resistance to freezing • Remains infectious for 3 months in water (uh oh!) • Targets pancreas and hematopoietic tissues of kidney and spleen . no envelope • Contains two segments of DS-RNA • Fairly stable and resistant to chemicals (acid. carriers not reduced .IPN: epizootiology (disease process) • Who?: All salmonids. digestive tract • Environmental factors: mortality reduced at lower temps (why?). experimentally by feeding infected material. vertical from adults to progeny. once a carrier always a carrier. however. virus particles shed in feces/urine • Transmission (how?): horizontal. brook trout most susceptible. by waters via carriers or infected fry. marine fish (flounder?) • Reservoirs (where)?: carriers. IP injection • Pathogenesis: entry via gills. IPN: pathology (what do we see?) . .i. pyloric cecae. spleen.e. vaccine exists now! . destruction of infected stock.IPN: detection. check these!!! • Presumptive tests: epizootiological evidence and/or typical PCR in infected cells • Definitive tests: serology (fluorescent antibody test (FAT)) • Control: avoid virus in water. virus-free stock. sex fluids are all good sources. diagnosis and control • Isolation: whole fry. kidney. How Bad Can It Be?? . Fish severely affected by IPNV: • Atlantic salmon* (Salmo salar) brook trout* (Salvelinus fontinalis) brown trout* (Salmo trutta) danio zebrafish* (Brachydanio rerio) rainbow trout* (Oncorhynchus mykiss) yellowtail* (Seriola lalandi) . Other species known to be susceptible… • amago salmon (Oncorhynchus rhodurus) Arctic char (Salvelinus alpinus) Atlantic menhadden (Brevoortia tyrannus) carangids (Carangidae) chinook salmon (Oncorhynchus tshawytscha) chum salmon (Oncorhynchus keta) cichlids (Cichlidae) coho salmon (Oncorhynchus kisutch) common scallop (Pecten maximus) cutthroat trout (Salmo clarki) cyprinids (Cyprinidae) Danube salmon (Salmo hucho) drums/croakers (Sciaenidae) eels (Anguilla spp) grayling (Thymallus thymallus) . amberjack (Seriola quinqueradiata) lampreys (Petromyzontyidae) loach (Misgurnus anguillicaudatus) masou salmon (Oncorhynchus masou) perches (Percidae) silversides (Atherinidae) soles (Soleidae) striped snakehead (Channa striatus) summer flounder (Paralichthys dentatus) white seabass (Moronidae) carp (Cyprinus carpio) redfin perch (Perca fluviatilis) yellowfin bream (Acanthopagrus australis) herrings/sardines (Clupidae) lake trout (Salvelinus namaycush) left-eye flounders (Bothidae) loaches (Cobitidae) Pacific salmon (Oncorhynchus spp) pikes (Esocidae) sockeye salmon (Oncorhynchus nerka) Southwest European nase (C.More… • halibut (Hippoglossus stenolepis) Jap. lethostigma) . toxostoma) suckers (Cotostomidae) turbot (Psetta maxima) whitefish (Coregonidae) goldfish (Carassius auratus) southern flounder (P. • coalfish (Pollachius virens) common carp (Cyprinus carpio) discus fish (Symphysodon discus) goldfish (Carrasius auratus) heron (Ardea cinerea) loach (Cobitidae) minnow (Phoxinus phoxinus) noble crayfish (Astacus astacus) Infectious pancreatic necrosis in Atlantic salmon..what now??? .. pike (Esox lucius) Note swollen stomach and 'pop eye' river lamprey (Lampetra fluviatalis) Source: Australian Animal Health Laboratory shore crab (Carcinus maenas) Spanish barbel (Barbus graellsi) white suckers (Catostomas commersoni) ..Asymptomatic carriers.. (2) Viral Hemorrhagic Septicemia (VHS) . acid. bullet-shaped (one rounded end).(2) Viral Hemorrhagic Septicemia (VHS) • What?: Viral disease of European salmonids • When?: Recognized in Denmark in 1949. heat. resistant to freeze-drying . 185 x 65 nM. isolated from Pacific Coast in 1989 • Size: rhabdovirus. lipoprotein envelope • non-segmented SS-RNA • Constitution: sensitive to ether and chloroform. usually rainbow trout. liver necrosis. spleen. birds. brown in Europe • Transmission: horizontal through water. coho (most cases in WA state) • Reservoirs: again. IP injection.. kidney • Epizootiology: cultured rainbow trout.Viral Hemorrhagic Septicemia • Produces a general viremia. hatchery equip . also brown trout. virus can occur on eggs spawned by carriers. chinook..survivors are life-long carriers. tissue and organ damage. steelhead. 200-300g fish most affected • Environmental factors: low temp (< 8oC. exopthalmia. pale gills w/focal hemorrhages .Viral Hemorrhagic Septicemia (VHS) • Pathogenesis: infection results in viremia. dark discoloration. disrupts many organ systems. 46oF) • External pathology: lethargy. swimming in circles. hemorrhages in roof of mouth. hanging downward in water (dropsy). or FAT. red and thin (acute) • Histopathology: necrosis of liver. epizootiological evidence.Viral Hemorrhagic Septicemia (VHS) • Internal pathology: gut devoid of food. hemorrhages in connective tissue. . spleen. definitive test is serum neutralization. kidney nephrons. liver pale. melanin in kidneys and spleen (OUCH!) • Isolation/tests: isolated from kidney/spleen. kidney gray and swollen (chronic). pancreas. Viral Hemorrhagic Septicemia (VHS) External hemorrhages Liver red in acute stage . Note swollen stomach and “pop eye” .Viral haemorrhagic septicaemia in rainbow trout. pinpoint haemorrhages in fatty tissue. and pale gills Source: T Håstein Viral haemorrhagic septicaemia in rainbow trout. Note pale color of stomach region. farmed and wild turbot in the Black Sea[11] II Marine fish of the Baltic Sea III Marine fish of the British Isles and northern France. and Korea[1][14] IV-b Freshwater fish in North American Great Lakes region[14] . Finland. and Greenland halibut (Reinhardtius hippoglossoides) in Greenland[12] IV-a Marine fish of the Northwest Pacific (North America).Type Prevalent host type and location I-a Farmed rainbow trout and a few other freshwater fish in continental Europe[10] I-b Marine fish of the Baltic Sea.[13] Japan. Kattegat. North Sea. North American north Atlantic coast. Japan[1] I-c Farmed rainbow trout Denmark I-d Farmed rainbow trout in Norway. farmed turbot in the UK and Ireland. Skagerrak. Gulf of Bothnia I-e Rainbow trout in Georgia. sensitive to heat and pH. non. 100 million mortalities between 1970-1980. if infected. glycoprotein is spiked on surface of virus .segmented SS-RNA. in young fish (fry: 90-95% mort. esp. cohos resistant • When?: 1950’s in Oregon hatcheries. 70% mortality likely.(3 ) Infectious Hematopoietic Necrosis (IHN) • Who: sockeye. rainbows. chinook. possible) • What?: bullet shaped rhabdovirus. . avoid infected broodstock.Viral Hemorrhagic Septicemia • Prevention: clean broodstock. Bleach kills the VHS virus. water = fish. test and slaughter • Can spread very quickly from farm to farm: avoid close proximity to other farms • Vaccines are under development. • One EPA-approved disinfectant: Virkon® AQUATIC (made by Dupont). incubation period depends on temp. adults shed virus at spawning • Transmission: horizontal.Infectious Hematopoietic Necrosis (IHN) • Reservoirs: survivors life-long carriers. death usually due to kidney failure . extensive hemorrhaging. route. feeding and inoculation have worked experimentally • Pathogenesis: gills suspected. Also. necrosis of many tissues. age. urine. however. and external mucus possible. feces. dose. primary mode is vertical via ovarian fluid (virus hitches ride on sperm into egg). Infectious Hematopoietic Necrosis (IHN) • Environmental factors: temp. very important. scoliosis • Internal pathology: liver. dropsy. spleen pale. slows below 10◦C. holding in tanks/handling increase severity • External pathology: lethargy. anemia. hemorrhaging of musculature/fins. stomach/intestines filled with milky fluid. exopthalmia. petechial hemorrhaging • Histopathology: extensive necrosis of hematopoetic tissue of kidney/spleen . kidney. whirling. ELISA • Prevention: avoidance. clean water with UV. disinfect. virus-free stock. . elevated water temp • No vaccines as of June 2007. vaccines under development. slaughter. test.Infectious Hematopoietic Necrosis (IHN) • Definitive diagnosis: serum neutralization. FAT. quarantine. ozone. disinfect eggs. icosohedral nucleocapsid with 162 capsomeres • Physio/chemical properties: easy to kill. Honduras • Acute hemorrhagia. high mortality. sensitive to freeze-thaw. . first discovered in 1968 • Agent: enveloped capsid. acid.(4) Channel Catfish Virus Disease (CCVD) • Contagious herpes virus affecting only channel catfish less than four months old • Occurs in SE United States. ether. California. etc. vertical suspected • external pathology: spiral swimming. hemorrhagic fins. ascites. pale or hemorrhagic gills. cooler water = big difference • epizootiology: horizontal. float with head at surface. abdomen. exophthalmia • Ipact 95 % ortality ( On Larva and fingerling) • Adlt as a carrier .Channel Catfish Virus Disease (CCVD) • Environmental factors: optimal temperature 28-30◦C. common during warmer months. other organs. kidney. macrophages in sinusoids of liver. degeneration of brain • Presumptive diagnosis: clinical signs. etc. congestion of mesenteries and adipose • Histopathology: necrosis of kidney.Channel Catfish Virus Disease (CCVD) • Internal pathology: hemorrhages of liver. epizootiological evidence . musculature. spleen.. gut. cleaning the stf with chlorine attenuated vaccine shows some promise • Therapy: none available. anage water qality and sanitation. . keep temperature below 27oC (will still produce carriers)..Channel Catfish Virus Disease (CCVD) • Prevention: avoid potential carriers (survivors) or infected fry.. Channel Catfish Virs Disease . Ephitelioma Populasum (cacar virus) Disebabkan oleh kualitas air yang buruk. . padat tebar yang tinggi target : ikan jenis carp Gejala : mncl bintik ptih susu berisi nanah yang menyebar sangat cepat mntp selurh permukaan tubuh dgn ketebalan 1-2 mm. Lakukan 3 kali penyuntukan selanjutnya dengan 5 % arsin dalam senyawa arycil . Penyuntikan pada perut ikan.Pengobatan Larutan arsenik 1 % dalam senyawa arycil. Lymphocystis Disebabkanoleh iridovirus/ DNA Dapat menyerang ikan air twar maupun laut Gejala: Terdapat penebalan pada sel jaringan ikat sehingga mncl tonjolan atau nodul pada ikan bisa berkelopok ata sendiri. hanya pencegahan melalui menjaga kualitas air dan peningkatan imunitas ikan. Sasaran uttama kulit atua insang. Tidak ada pengobatan yg efektiv. . Penularan melalui makanan atapun suntikan dan air. . insang membsk. kllit melepuh. ikan megap megap.terdapat keruskan insang ( bintik putih dan merah pada insang) menyerang insang dan ginjal ikan sehingga terbentuk inflamasi pada ginjal.Koi Herpes Virus (KHV) Disebakan virus DNA dari strain herpes viridae menyerang ikan mas (Cyprinus)dan koi muncul : temperatur turun dan kualitas air buruk Gejala : nafsu makan turun. kematian 1-5 hari. Sering diikuti infeksi sekunder oleh bakteri dan jamur ketika luka ada di permukaan tubuh . desinfeksi pada semua perslatan dan kolam.Pengobatan Segera dipindahkan ikan yang sakit (isolasi) ke suhu air yang lbh tinggi ( 30 C) selama beberapa hari kemudian suhu diturunkan sampai 27 C keumdian dikeluarkan. mnitoring dan evaluasi ikan dan lingkngan . pemberian pakan yg baik dan sehat. penggunaan benih yang berkalitas dan bebas KHV. Jika sdah mewabah sebaiknya dimusnahkan Pencegahan : padat tebar dikurangi. mnjaga kualitas air. Dilanjtkan pengobatan seknder. . berenang yang tidak teratur. warna tubuh menjadi gelap. Kerusakan pada retina mata. Menyebkan kematian 50 % Penyebaran dengan horisontal maupun vertikal Vaksinasi diperlukan untuk mencegah VNN Pencegahan : manage Kualitas air. posisi terapung dengan perut diatas karena pembengkakan. pakan dan lingkungan serta sarana budidaya.Viral Nervous Necrosis (VNN) Penyebab : Betanodaviruses family Nodoviridae Menyerang larva ikan sampai dewasa (ikan laut) Target serangan : sistem syaraf dan retina Gejala : Nafsu makan turun. benih. . . you can always take precautions! .However.