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Microbio-virology > Retroviridae > Flashcards

Retroviridae Flashcards

1
Q

Retroviruses

A
  • Genetic info maintained in an RNA molecule
  • converts RNA to DNA
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2
Q

Subfamily: Orthoretrovirinae

Alpharetrovirus

A

Avian leukosis/sarcoma complex

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3
Q

Subfamily: Orthoretrovirinae

Betaretrovirus

A

ovine pulmonary adenomatosis (Jaagsiekte)

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4
Q

Subfamily: Orthoretrovirinae

Gammaretrovirus

A

Feline leukemia virus (FeLV)

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5
Q

Subfamily: Orthoretrovirinae

Deltaretrovirus

A

Bovine leukosis virus (BLV)

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6
Q

Subfamily: Orthoretrovirinae

Lentivirus

A

Caprine arthritis encephalitis

equine infectios anemia

bovine immunodeficiency

feline immunodeficiency

maedi-visna

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7
Q

Subfamily: Orthoretrovirinae

Epsilonretrovirus

A

Walleye dermal sarcoma

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8
Q

Subfamily: Spumaretrovirinae

A

Bovine-feline -‘foamy’

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9
Q

Retroviruses

A
  • Diploid genome: two copies of ss-positive-sense RNA
  • Reverse transcriptase produces DNA intermediates from genomic RNA
  • viral genome integrates into cell genome using integrase
    • can activate or inactivate host genes
  • RNA-dependent DNA polymerase replicates viral genome
  • Enveloped viruses released by budding from cells membranes
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10
Q

Feline Leukemia virus

A
  • naturally occurring exogenous gammaretrovirus enzootic in domestic and wild cats
  • Infection is life-long
    • malignant and proliferative
    • opportunistic infections and anemia common: gingivitis/ulcers
  • Infection prevalence usualy <2%
    • can be up to 30%
    • More common in catteries/multi-cat household
    • Also in outdoor cats
    • kittens more susceptible
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11
Q

Feline leukemia virus (FeLV)

Transmission

A
  • Horizontal-most important route
    • outddor cats
    • older cats
    • male cats (saliva infective)
    • kittens more susceptible (nursing and grooming)
  • Vertical
    • transplacentally
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12
Q

Feline leukemia virus

Pathogenesis

A
  • Initial replication in oral/pharyngeal lymphoid tissue
    • then systemic spread via lymphocytes, monocytes, macrophages
  • Progressive infection
    • heavy virus replication in lymphoid tissue, bone marrow, mucosal and glandular epithelial tissues
  • Exposed cats seldome escape infection
  • Genomic changes may result in higher replication/inc virulence
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13
Q

Feline leukemia virus

Diversity

A
  • Infection usually involved genetically distinct/antigenically related exogenous FeLVs
  • Virus diversity thru mutations/recombination
  • Virulent traits located in LTR and SU glycoprotein
    • minimal changes in SU glycoprotein can dramatically alter receptor use and disease
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14
Q

FeLV sub-groups based on SU glycoprotein

pathogenic determinants

A
  • FeLV-A
    • minimally pathogenic unless recombined or mutated
  • FeLV-B
    • recombinants of FeLV-A (SU) and related endogenous viruses
    • linked to thymus lymphosarcoma and lymphoid tumors
  • FeLV-C
    • recombinants of FeLV-A and related endogenous virsues
    • associated with severe aplastic anemia
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15
Q

Clinical signs associated with FeLV infection

A
  • uneven pupils (anisocoria)
  • uveitis
  • enlarged lymph nodes
  • chronic wounds and infections (cutaneous lesions/abcesses)
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16
Q
A

FeLV

17
Q

Pathologies associated with FeLV infection

A
  • Feline lymphosarcomas or lymphomas
  • Myeloproliferative dz and anemia
  • Immunopathologic dz => immune-complex mediated/immunodeficiency
  • Fibrosarcoma => induced by replication defective feline sarcoma virus
18
Q

FeLV-associated lymphosarcomas

A
  • Incidence of lymphosarcomas declined
  • Multicentric => tumors in lympoid and non-lymphoid tissues
  • Thymic => mostly kittens
  • Alimentary
    • usually older cats
    • GI/ Mesenteric lymtph nodes
  • Unclassified
    • non lymphoid tissue
    • Skin, eyes, CNS
19
Q

FeLV-associated myeloproliferative dz and anemia

A
  • Erythremic myelosis => erythroid progenitor cell
  • Granulocytic leukemia => granulocytic myeloid progenitor cell
  • Erythroleukemia => erythroid and granulocytic myeloid precursors
  • Myelofibrosis => proliferation of fibroblasts
20
Q

FeLV-associated immunopathologic dz

A
  • Immune-complex mediated
    • presistently high FeLV antigen-antibody complexes produce glomerulonephritis
    • lymphocyte depletion by antibody-mediated cytotoxicity against FOCMA on lymphocyte membrane
  • Immunodeficiency
    • chronic stomatitis
    • gingivitis
    • non-healing skin lesions
    • subcutaneous abscesses
    • CRD
    • FIP
    • infertility
    • fetal deaths
    • abortion
21
Q

Feline leukemia virus

Dx

A
  • Antigen detection
    • kits based on p27 (group specific antigen)
    • p27 found in progressively infected cats
    • some infected cats may not have detectible intigen in blood at time of test
    • Immunofluorescence takes an expert
  • RT-PCR
    • detects FeLV provirus as evidence of infection
    • vaccination doesn’t interfere with antigen tests (unless sampled immediately after vaccination)
22
Q
A
  • FeLV-associated lymphoma of mediastinal lymph node
  • normal architecture of Lymph node is gone
23
Q

Feline leukemia

Immunity, prevention, control

A
  • test and secregate infected cats
  • vaccine may protect against progressive infection and dz
  • does not prevent against infection
    • ​Don’t induce cell-mediated immunity
  • vaccines w/adjuvants may induce granulomas
  • recombinant canarypox doesn’t contain adjuvants
    • expresses env and gag FeLV antigens
    • vaccinate at 9 weeks, re-vaccinate 3 weeks later, then annually
24
Q

FeLV and lymphosarcomas

A
  • Development associated with at least 6 conserved cellular integration sites
    • dysregulation of cellular oncogenes controlling cell division
  • c-myc and v-myc in transformed lymphocytes
25
Q

Ovine pulmonary adenomatosis

Jaagsiekte sheep retrovirus-JSRV

A
  • adults sheep dz
    • wasting and resp distress
  • orig S. Africa => now worldwide
    • not in Australia/New Zealand
    • eradicated from Iceland
  • Reportable in some US states
  • may be resp for 25% annual sheep mortality in Peru
  • Caused by type D retrovirus: betaretrovirus
26
Q

Ovine pulmonary adenomatosis

Clinical features

A
  • Long incubation period
    • severe losses seen in sheep > / = 2 yrs old
  • Progressive dyspnea, anorexia, cacexia
  • Resp failure (death from blockage small airways/anoxia)
    • lots of fluid in lungs (drown sheep)
    • type II pneumocytes (epithelial cells)
      • disseminated in neoplastic nodules responsible for secreting the extra fluid
  • fluid from nostrils when head lowered
27
Q

Ovine pulmonary adenomatosis

Transmission/pathogenesis

A
  • aerosolized lung fluids/close contact
  • transforms differentiated lung epithelial (pneumocytes type II) in terminal airways
    • bronchioles and alveoli
  • Proviral DNA in pneumocytes II, lymph tissue, alveolar macrophages, PBLs
  • Active replication probably restricted to bronchoalveolar epithelial cells
  • Sheep don’t develop antibodies… (no test)
28
Q

Introduction of Jaagsiekte

A
  • Usually by introducing infected sheep to flock (Rams)
  • Facilitated by close contact houseing
29
Q

Ovine pulmonary adenomatosis

Patohlogy

A
  • Nodular lesions in lung at slaughter/necropsy
  • Microscopic pathology indicates epithelial proliferation in bronchioles and alveoli
  • Tumors correspond to adenoma or adenocarcinoma
  • Metastes
    • not common
    • can occur to regional/pulmonary lymph nodes
30
Q

Ovine pulmonary adenomatosis

Gross review lungs

A
  • Won’t deflate
  • mottled with coalescing to diffuse proliferative areas (pale pink) with red areas (atelectasis)
  • Large, firm, gray coalescing proliferative and fibrotic masses
31
Q

Ovine pulmonary adenomatosis

DIagnosis

(21:58)

A
  • Lack of antibody response
    • immunological tolerance triggered by closely related endogenous retroviruses
  • ​Clinical Signs
    • too late
  • Detection in colostrum/milk
  • Virus isolation….?

Microbio-virology (8 decks)

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