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10 Cards in this Set
- Front
- Back
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What are the properties of Parvoviridae?
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♦PROPERTIES
-small non-enveloped viruses that contain a single strand of DNA -viruses contain minimal information for replication and rely on proteins (ie. DNA polymerase II) encoded by host cells for many steps in replication -only capable of replicating in the nuclei of rapidly dividing cells (during the S phase of division) ie. bone marrow & GI tract -affected animals have profuse, watery diarrhea, and suppression of bone marrow production, which leads to dramatic decreases in all white cell classes in the blood (panleukopenia) -destroys rapidly dividing cells in any organs developing in a fetus (it can cross the placenta) -cardiac muscle damage in dogs & cerebellar hypoplasia in cats are observed following fetal infection -virus is shed in feces -extremely resistant in the environment and disinfection after contamination is a challenge -recovery from infection is accompanied by humoral immunity -provoke high antibody response -vaccines provide solid immunity -produces nice inclusion bodies |
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How does age affect host manifestations?
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♦Generalized neonatal disease - C & D → 2-12 days
♦Leukopaenia - C & D → 2-4 months ♦Enteritis - C & D → 4-12 months ♦Cerebellar hypoplasia - C → 2-4 weeks, due to infection in utero when cerebellum was developing, often have to be put down ♦Myocarditis - D → 3-8 weeks, puppies that died suddenly |
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Feline Panleukopenia
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-infection is via the oropharynx and initial infection is followed by viraemia
-virus is shed in the diarrhea and this is the source of infection -virus then replicates in actively dividing cells ie. bone marrow and crypts -clinical signs are related to damage to the integrity of the intestinal epithelium which results in diarhea, and to the drop in WBCs (panleukopaenia) -infection in fetus = cerebellar hypoplasia -control is with strict hygiene and quarantine of incoming animals -vaccination is effective (however high titers of antibody may pass into the colostrum after natural infection and this could interfere with vaccination if it binds with the injected antigen) |
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Canine Parvovirus
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-Rottweiler's more susceptible
-pathogenesis is similar to feline leukopenia ie. shed in feces -however in fetal infection it is the myocardial cells that are damaged rather than those of the cerebellum -3 syndromes were recognised: generalized neonatal disease, myocarditis following fetal infection, and leukopania/enteritis syndrome (most common) -vaccine available |
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Porcine Parvovirus
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-MOST IMPORTANT CAUSE OF REPRODUCTIVE LOSS IN PIGS THROUGHOUT THE WORLD
-clinical signs depend on stage of gestation at which infection occurs -infection in the 1st weeks after breeding leads to fetal death and resorption -infection in later gestation results in birth of a litter of pigs that manifest a variety of signs depending on when the virus invaded each fetus and the dose of virus reaching each fetus -thus a liter may be composed of normal appearing piglets, weak runts, and mummified fetuses -vaccination is used in some piggeries but in many there is reliance on natural infection occurring before breeding from virus present in the environment. This means that piggeries with a high standard of hygiene are most susceptible unless they vaccinate regularly. |
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How do we diagnose parvoviral diseases?
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-clinical signs and haematology are useful in initial diagnosis of parvoviral infections of dogs, cats and the typical appearance of aborted piglets is very suggestive in pigs
-confirmation of infection is best achieved by detection of virus or viral antigen in diarrhoeic feces (dogs & cats) or viral antigen in tissues of aborted pigs -serological testing of the bitch, queen, or sow provides limited information -detection of antibody indicates past infection |
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What are the properties of Circoviridae?
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-attacks rapidly dividing cells (replicates in nucleus) but infects other cells too
-smallest known viruses of mammals -non-enveloped and spherical |
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Chicken anaemia virus
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-chickens get this from silently infected hens (infected as adults)
-infection can be transmitted horizontally but of considerable importance is the fact that vertical transmission through egg occurs regularly -in chicks it is generalized and causes lymphodepletion and suppression of erythropoiesis -10-50% of chicks die -survivors are susceptible to other infections that would usually be inapparent -encodes a proteins that induces apoptosis of T lymphocytes -serological tests are available to detect infected flocks -initial diagnosis requires virus isolation, although history, clinical, and postmortem signs are suggestive -a vaccine is used in some countries |
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Psittacine Beak & Feather Disease
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-affects cells of beak & claw causing deformities
-disease of Australian parrots -most often seen in young birds after first feather formation -diagnosis is based on clinical appearance, identification of basophilic intracytoplasmic inclusion bodies in follicular epithelium and electron microscopy to identify masses of virus particles in feather follicles -does not resolve but some live for a while without feathers -no vaccines |
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Porcine circovirus 1 & 2
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♦PCV 1
-PCV 1 is widespread in pig populations -single stranded DNA in a single loop -found in pig kidneys -no role in any disease of pigs ♦PCV 2 -distinct virus -has been associated with post-weaning multisystemic wasting disease -possibly some other factors is involved as well -present in Australian pigs but the disease PMWS is not -diarrhea, abnormal scaly skin, great enlargement of lymph nodes -pigs don't grow well -10-15% mortality |
