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Erythrovirus hosts
humans and NHP
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parvovirus (genera) hosts
- swine, cats, dogs, mink, mice, rats, hamsters, geese ducks
- NOT PRIMATES/HUMANS
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Parvovirus specs
- non-enveloped icosahedral tiny ssDNA (2 genes with overlapping proteins), great in environment
- Replicate in DIVIDING cells
- Immunity/vaccines are great (AMDV)
- maternal immunity protects young but prevents vaccination
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Canine parvovirus
- parvovirus (ssDNA, unenveloped, replicates in dividing cells)
- variant of same virus as mink enteric and feline panleukopenia
- most dz in young (b/c dividing)
- mostly enteritis, oronasal infection spreads to lymphoid tissues, cell loss. LYMPHOPENIA.
- Infects crypts of Lieberkuhn. Congestion and thickening of mucosa, blunted villi, dilated crypts, occasional intranuclear inclusions. LN enlarged, edemetous. Marrow pale and fluid.
- Myocarditis (from neonatal infection). Die suddenly or post-dyspnea. Focal myocardial necrosis, fiber loss.
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feline panleukopenia virus
- parvovirus (ssDNA, unenveloped, replicates in dividing cells)
- variant of same virus as mink enteric and canine parvo
- most dz in young (b/c dividing)
- mostly enteritis, oronasal infection spreads to lymphoid tissues, cell loss. PANLEUKOPENIA.
- Infects crypts of Lieberkuhn. Congestion and thickening of mucosa, blunted villi, dilated crypts, occasional intranuclear inclusions. LN enlarged, edemetous. Marrow pale and fluid.
- Feline cerebella disease - fetal or neonatal - lesions in external granular layer of cerebellum. Rapid cell division arrested, permanent ataxia.
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mink enteritis virus
- parvovirus (ssDNA, unenveloped, replicates in dividing cells)
- variant of same virus as canine parvo and feline panleukopenia
- most dz in young (b/c dividing)
- mostly enteritis, oronasal infection spreads to lymphoid tissues, cell loss.
- Infects crypts of Lieberkuhn. Congestion and thickening of mucosa, blunted villi, dilated crypts, occasional intranuclear inclusions. LN enlarged, edematous. Marrow pale and fluid.
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porcine parvovirus
- parvovirus (ssDNA, unenveloped, replicates in dividing cells)
- repro failure, SMEDI (stillbirth, mummification, embryonic death, infertility), rarely skin vesicular disease and neonatal systemic disease. Asymptomatic in all but fetuses, combined infections may be severe.
- Signs: sows returning to estrus (early fetal death), or death of proportion of fetuses, piglets born smaller and weak. at 55-70d, extensive infection and die pre-birth. After 70d, less severe, possible leukopenia.
- Boars shed in semen
- Even modified live vaccines safe in pregnant females.
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Aleutian mink disease virus
- parvovirus (ssDNA, unenveloped, replicates in dividing cells)
- disease in farmed mink (also mild in skunks, ferrets).
- Acute dz in neonates: infects type II pneumocytes (pneumonitis).
- Older: plasmocytosis, hypergammaglobulinemia, glomerulonephritis, arteritis, hepatitis, death.
- Immune complex disease, not controlled by immune responses. Recessive, causes pale (Aleutian) coat color. Lysosomal storage disease.
- Vaccines would make it worse (hypergammaglobulinemia diagnostic).
- Eradicated in some countries due to culling.
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Circoviridae
- ssDNA, SMALLEST, icosahedral, no envelope, good in environment, require dividing cells. Immunity is great, disease mostly only with co-infection.
- psittacine beak and feather disease, porcine circovirus, chicken anemia agent
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canine circovirus
- ssDNA, smallest, icosahedral
- new dog virus, shed in feces. Little known - diarrhea?
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Psittacine beak and feather disease
- circovirus, ssDNA, smallest, icosahedral
- cockatoos, parrots, budgerigars
- feather loss, abnormal feathers. Beak shiny, overgrown, broken. Dystrophic feathers replace healthy ones, downy first. May be featherless for years
- Acute hepatitis and immunosuppression (secondary common).
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chicken infectious anemia agent
- circovirus, ssDNA, smallest, icosahedral
- acute worldwide immunosuppressive disease in young chickens (anorexia, lethargy, depression, anemia, atrophy, hypoplasia of lymphoid organs). Attacks lymphoid tissues, then liver/thymus/skin
- Breeder hens may be asymptomatic but carry in repro tract. Chicks infected in egg or after, clinical signs at 2-3wks. Adults asymptomatic
- Viremia for up to 35 days. Anemia due to decreased erythrocytosis. Resistant by 2 weeks. Maternal prevents dz but not infection.
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porcine circovirus 2
- circovirus, ssDNA, smallest, icosahedral
- Porcine Circovirus Associated Diseases (PCVD)
- ADR, tachypnea, dyspnea, pallor/jaundice, bronchopneumonia, lymphadenopathy. Lymphocyte depletion, lympho-histiocytic cellular infiltrations, multinucleated giant cells
- requires co-infection (Porcine Parvo, Porcine Reproductive Respiratory Syndrome Virus, mycoplasma, etc)
- 2nd virus activates immune, circo kills more immune cells.
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two kinds of retroviruses
- (+RNA = retroviruses, dsDNA = hepadnaviruses, both enveloped)
- Oncogenic retroviruses (cancer - avian leukosis, ovine pulmonary adenomatosis, feline leukemia virus, bovine leukemia virus)
- Lentiviruses
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retrovirus replication
- enveloped
- attach to special receptor on cell
- RME
- reverse-transcription of RNA to DNA in cytoplasm
- passive mechanism to transport into nucleus (oncoviruses).
- Silent while separate (plasmid-like). "Provirus" until transcription and translation starts.
- Budding/exocytosis (viruses that cause cancer CAN'T BE LYTIC)
- Very efficient, though lots of mistakes.
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Retroviruses
- +RNA enveloped, reverse-transcriptase
- Simple (only gag, pol, and env genes) (FeLeuk) vs complex (additional genes to regulate replication) (bovine leuk)
- SLOWLY produce disease (few exceptions). Transmission inefficient.
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how do simple retroviruses become oncogenic
- DNA migrates passively into nucleus, integrates into host genome. If it integrates upstream of a host cell proto-oncogene, retroviral promoter will increase expression of proximal host genes
- Highly oncogenic viruses are often replication-defective. Virus has to be rescued by a replication-competent "helper" virus. Tumors arise VERY quickly
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Avian leukosis
- Retrovirus (+RNA, reverse transcriptase, enveloped)
- Endogenous (integrated into genome) in pretty much all chickens. Most flocks are free of exogenous (so epidemics are rare).
- after 5-6d post-birth, produce neutralizing antibody and clear infection. If infected earlier, immunologically tolerant, viremia for life (appear normal but are reservoir), eventual tumors.
- See lymphoid leukosis or lymphomatosis in spleen, liver, bursa of Fabricious. B cell origin, secrete IgM. Inappetance, emaciation, weakness, abdominal distension.
- osteopetrosis - diaphyseal or metaphyseal thickening with chrondrosarcoma or osteoma
- erythroblastosis, myeloblastosis or myelocytomatosis, in circulation or aplastic anemia (bone marrow = tumor)
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Ovine Pulmonary Adenomatosis (Jaagsiekta)
- retrovirus (+RNA, reverse transcriptase, envelope)
- spread by aerosol. Months to years, transforms type II pneumocytes to produce more mucus with tumor nodules, compromise lung function. Bacterial infections secondary.
- Emaciation, coughing/dyspnea, lagging behind, positive wheelbarrow test.
- LONG incubation, CULL
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Feline Leukemia Virus
- Retrovirus (+RNA, reverse transcriptase, envelope)
- #1 infectious COD of cats
- releated to immunosuppression like FIV.
- replicates in tonsillar CD4 and CD8 T and B. Thymic atrophy, depletion of cells in paracortex of LN, failure of interferon production.
- vaccinated = not shedding, healthy, occasionally re-activates in old cats. Not vaccinated = 2/3 self-cure and 1/3 are viremic for life. Prognosis poor, shed virus in saliva.
- Dz depends on age
- gingivitis, chronic stomatitis, stunting, failure to thrive, recurrent infections (susceptibility to FIP). Possibly poor fertility, fetal death, and abortion. Immune complexes cause glomerulonephritis. Lymphoma. Antibodies aren't very helpful, so neither is vax.
- Subtypes: A = immunosuppression, B = neoplasia (A and B go together), C = aplastic anemia
- often coinfects as "helper" with Feline Sarcoma Virus (makes envelope protein to "rescue" Sarc)
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Feline Sarcoma Virus (FeSV)
- retrovirus (+RNA, enveloped, reverse transcriptase)
- Defective virus derived from FeLV with oncogene instead of pol gene. Feline Leukemia makes an envelope for Sarcoma virus (viral particles with an envelope protein encoded by different viruses are pseudotypes)
- Delivers an oncogene to every cell it infects, so lots of oncogenesis
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Bovine Leukemia Virus
- Retrovirus (+RNA enveloped, reverse transcriptase).
- inefficient transmission so likely iatrogenic (only if sheep nurse from cows)
- transforms B lymphocytes causing lymphocytosis for years (often only sign). Tumors in LN, spleen, abomasum, heart, uterus, kidneys, meninges, brain meninges. Signs depend on tumors.
- Complex - has TAX protein (transcriptional trans-activator, makes LOTS of viral RNA).
- Transmission is inefficient so it's pretty easy to cull positive and get a seronegative herd.
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Lentiviruses
- family retroviridae (+RNA, reverse transcriptase, enveloped), meaning slow. Causes chronic disease, inefficient transmission. Complex replication with extra genes to expedite each step. More controlled and efficient replication than retro. More lytic, less cancer.
- Make quasi-species within each animal (new genetic variants inside host, escape immune).
- NO GOOD VAX
- Visna/Maedi/ Ovine Progressive Pneumonia, Caprine Arthritis/Encephalomyelitis, Equine Infectious Anemia
- Feline Immunodeficiency Virus
- Bovine Immunodeficiency Virus
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Visna/Maedi or Ovine Progressive Pneumonia
- Lentivirus (retrovirus, +RNA env) of Icelandic Sheep (Maedi=dyspnea, Visna = dementia) (Eradicated in Iceland)
- Aerosol, milk, fomites and arthropods
- Cell-associated viremia in monocytes, trojan horse until macrophages.
- Incubation for 2-8 YEARS.
- "Immune Escape" - changes regularly, avoids immune recognition. Inflammation leads to organ failure.
- Mononuclear cells fill alveoli and udder
- Monocytes fill meninges and subependymal spaces = demyelinating leukoencephalomyelitis.
- Increasingly exercise intolerant, dyspnea eventually, cachexia, death. Death is faster if pregnant or coinfected, or stressed. Encephalitis rare, udder heavy and firm, arthritis/lameness
- No vax, cull
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Caprine Arthritis/Encephalomyelitis
- Lentivirus (retrovirus +RNA env)
- common, esp in dairy goats, transmitted through milk.
- Infects monocytes in gut, starts lytic replication once macrophages. Macrophages lodge in synovia of joints, synovial hyperplasia with monocyte inflammatory infiltrate (lymphocytes, plasma, macrophages), demyelination and malacia.
- Lameness, swollen joints (esp carpi), ascending paresis, paralysis, paddling, death (Esp kids)
- No good vax
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Equine Infectious Anemia
- Lentivirus (Retrovirus, +RNA, env)
- Transmission iatrogenic or biting arthropods (MECHANICAL). NOT spread in milk. Intrauterine possible.
- Lifelong cell-associated viremia in mononuclear, infected macrophages in spleen, LN, liver, kidney, lung, adrenal. Waves of disease when new strains/genetic variants (= immune escape)
- Anemia from bone marrow suppression, autoimmune attack of RBC or increased clearance of RBCs. Vasculitis and glomerulonephritis from immune complexes lodging in glomeruli. Hemorrhage from thrombocytopenia.
- Marked fever, weakness, severe anemia, jaundice, blood-stained feces, tachypnea, petechial hemorrhage of mucosae. Recurrent, normal or chronic (mild vs cachexia/edema/anemia).
- Coggins Test (agar gel immunodiffusion measuring EIA antibody), very accurate but not with vax, maternal, etc. Negative required for transport
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Feline Immunodeficiency Virus
- Lentivirus (retrovirus, +RNA, env)
- Infected via bites, NOT by queen grooming kittens. Queens (acute infection) can shed virus in colostrum and milk, infect kittens.
- Infects CD4 in regional LN, Tcell associated viremia, generalized lymphadenopathy. WEEKS TO MONTHS later = neutropenia. Persists for years, eventual immunodeficiency.
- Signs overlap FeLV (immunosuppressive); gingevitis, slow weight loss, poor coat, anemia, chronic infections, CNS disease including mental deterioration and sz, fluctuating anemia and leukopenia.
- SNAP (but false +, so western blot after)
- vax not great, confuses testing.
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Equine Arteritis Virus
- Arterivirus - +RNA enveloped (nested sub-genomic transcripts)
- mostly asymptomatic, can see abortion with no clinical in mare. In (rare) severe, depression, urticaria (head/neck/trunk), periocular edema, abdomen and hind limb stiff gait. Most recover, VERY rare interstitial pneumonia and intestinal necrosis.
- alveolar macrophages, systemic to most tissues, esp macrophages, endothelium, mesothelium = vascular damage (edema, hemorrhage, congestion). Can be in semen.
- Transmission via resp, sexual, transplacental.
- Vax, but maybe not worth it (rare)
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Porcine Reproductive and Respiratory Syndrome Virus (PRRSV)
- Arterivirus, +RNA enveloped icosahedral, nested subgenomic
- Pigs.
- ADR, cyanosis of ears and snout, abortion/premature/stillbirth/mummification. Depends on age, worse in youngest
- Co-infects with Porcine Circovirus-2
- tropism for mucosal and resp macrophages then LN, systemic viremia infecting monocytes and macrophages
- Recovered are protected, but persistent shedding (can be caused by vax)
- transmission via contact, sexual, airborne, needles/tattooing equipment, semen
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Simian hemorrhagic fever virus
- Arterivirus, +RNA, Enveloped, icosahedral, subgenomic nested transcripts
- Macaques (New World)
- fever, facial edema, dehydration, skin petechia, diarrhea, hemorrhages (dermis, nasal mucosa, lungs, intestines), shock, death.
- Virus from asymptomatic African primates.
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