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Virology > Retroviridae (Final) > Flashcards

Retroviridae (Final) Flashcards

1
Q

What are Retroviruses causative agents of?

A

cancer
immunosuppression
immunodeficiency diseases

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2
Q

Describe the enzyme encoded by Retroviridae

A

Reverse Transcriptase

  • an RNA-dependent DNA polymerase
  • needed to replicate
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3
Q

General Features of Retroviridae

  • structure
  • genome
A
  • enveloped, spherical
  • studded with glycoproteins
  • matrix layer
  • diploid genome with 2 copies of single stranded pos sense RNA
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4
Q

What are the 4 important genes in Retroviridae?

What do they each encode?

A
  • gag gene: encodes virus core proteins
  • pol gene: encodes reverse transcriptase and integrase
  • env gene: encodes envelope proteins, surface, and transmembrane
  • pro gene: encodes protease
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5
Q

What diseases are caused by Alpharetroviruses?

A

Viruses of Chickens

  • avian luecosis virus
  • avian sarcoma virus
  • avian myeloblastosis virus
  • rous sarcoma virus
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6
Q

What diseases are caused by Betaretroviruses?

A
  • Mouse mammary tumor virus
  • Mason-Pfizer monkey virus
  • Jaagsiekte of sheep
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7
Q

What diseases are caused by Gammaretroviruses?

A

Viruses of Reptiles and Mammals

  • feline leukemia virus
  • feline sarcomavirus
  • avian reticuloendotheliosis virus
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8
Q

Alpharetroviruses

  • simple or complex?
  • genes contained
  • type of virion morphology
  • endo, exo, or both?
A
  • simple retrovirus
  • gag, pol, pro, and env genes
  • type C virion morphology
  • endogenous and exogenous viruses
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9
Q

Betaretroviruses

  • genes contained
  • endo, exo, or both?
A
  • gag, pro, pol, env
  • MMTV also contains sag gene which encodes the superantigen
  • endogenous and exogenous viruses
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10
Q

Gammaretrovirus

  • simple or complex?
  • genes contained
  • type of virion morphology
  • endo, exo, or both?
A
  • simple retrovirus
  • gag, pro, pol, env
  • type C virion morphology
  • endogenous and exogenous viruses
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11
Q

Deltaretroviruses

  • simple or complex?
  • type of virion morphology
  • genes contained
  • endo, exo, or both?
A
  • complex retrovirus
  • type C virion morphology
  • gag, pro, pol, env, and regulatory genes rex and tax
  • rex and tax control synthesis and processing of viral RNA
  • only exogenous
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12
Q

What diseases are caused by Deltaretroviruses?

A
  • Human T-lymphotrophic virus

- Bovine leukemia virus

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13
Q

Epsilonretroviruses

  • single or complex?
  • type of virion morphology
  • genes contained
  • endo, exo, or both?
A
  • complex retrovirus
  • type C virion morphology
  • gag, pro, pol, env, ORF A, B and C
  • only endogenous
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14
Q

What diseases are caused by Epsilonretroviruses?

A

Viruses of Fish and Reptiles

- Walleye dermal sarcoma virus

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15
Q

Lentiviruses

  • simple or complex?
  • morphology
  • genes contained
  • endo, exo, or both
A
  • complex viruses
  • cylindrical or conical shaped core
  • gag, pol, pro, env, and accessory genes
  • exogenous in many mammals
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16
Q

Functions of the 4 accessory genes found in Lentiviruses

A
  • tat gene: encodes a transactivator that enhances RNA polymerase
  • rev gene: encodes protein that facilitates transport of non-spliced viral RNA from nucleus to cytoplasm
  • nef gene: encodes nef protein that is needed for replication, and down regulates CD4 molecule
  • vif gene: encodes vif protein that enhances replication in lymphocytes
17
Q

What diseases are caused by Lentiviruses?

A
  • human immunodeficiency virus (HIV)
  • caprine arthritis encephalitis virus
  • meadi-visna virus
18
Q

Spumaviruses

  • simple or complex?
  • morphology
  • genes contained
  • endo, exo, or both
  • main disease caused
A
  • complex virus
  • spikes on surface, uncondensed core
  • gag, pro, pol, env, tas/bel-1, bet
  • exogenous viruses in mammals
  • Human foamy virus
19
Q

How retroviruses cause acute vs chronic transformation

A
  • acute: viruses contain viral oncogenes

- chronic: insertion/mutation through random integration into host genome

20
Q

Feline Leukemia

  • genus
  • genes contained
  • subtypes
A
  • gammaretrovirus
  • env, pol, gag
  • A: in every infection
  • B: recombination of FeLV A with enFeLV
  • C: mutations in the env gene
  • T: tropism for T lymphocytes
21
Q

Feline Leukemia transmission

A
  • virus shed from saliva, nasal secretions, feces, and milk
  • transmitted via bites and grooming
  • risk: young, high population, poor hygiene
  • embyronic death, stillbirth, or viremic kittens
22
Q

Pathogenesis of Feline Leukemia

A
  • SU protein determines pathogenicity
  • infection through oral or pharyngeal tissue
  • spreads through monocytes and lymphocytes
  • viremia develops
  • tropism to lymphoid tissue
  • defects in T cells
  • wasting syndrome and thymus atrophy
  • low or no cellular immunity
23
Q

Clinical signs of Feline Leukemia

A
  • immunosuppression
  • non-regenerative anemia caused by chronic inflammatory mechanisms
  • myelodestruction, myelosuppression, myeloproliferative diseases
  • lymphoma or leukemia
24
Q

Diagnosis of Feline Leukemia

A
  • p27 ELISA
  • immunofluorescence assay
  • virus isolation in cell culture (best)
  • RT-PCR
  • reverse transcriptase PCR
  • serology
25
Q

Feline Immunodeficiency Virus (FIV)

  • genus
  • general mechanism of disease
  • at risk animals
A
  • Lentivirus
  • attacks immune system, so weakens immune response to infections and cancers
  • outdoor, free roaming cats, aggressive males
26
Q

Pathogenesis of FIV

A
  • replicates in lymphocytes
  • binds to activates CD4 cells, reducing this cell type
  • reduction of IL-2 production
  • lymphopenia
  • activates Treg
  • increases IL-10 production
  • immunosuppression
27
Q

Transmission of FIV

A
  • primarily through deep bite wounds and scratches
  • infected mother to kittens during passage through birth canal
  • in utero or through milk is rare
28
Q

Clinical signs of FIV

A
  • poor coat condition, persistent fever
  • loss of appetite, lethargy
  • gingivitis, stomatitis
  • urinary bladder and upper resp infections
  • slow weight loss, severe wasting
  • cancer and blood diseases may develop
  • abortion
29
Q

Diagnosis of FIV

A
  • ELISA
  • immunoblotting
  • PCR
30
Q

Which genus’s infect chickens?

A
  • Alpharetrovirus, Gammaretrovirus
31
Q

Thick Leg Syndrome

  • type of condition
  • cause by what?
  • effects/pathogenesis
A
  • osteoporosis
  • caused by replication defective avian retrovirus
  • affects long bones of the legs
  • results in uniform or irregular diaphyseal and metaphyseal thickening of affected bones
32
Q

Erythroblastosis

  • caused by what?
  • target
  • signs
A
  • cellular transformation of oncogenic virus
  • targets progenitor erythroblasts
  • liver and kidneys may be swollen
  • anemia
  • erythroblasts in blood
33
Q

Equine Infectious Anemia Virus

  • also called what?
  • genus
A
  • Swamp fever

- lentivirus

34
Q

Equine Infectious Anemia Virus transmission

A
  • blood
  • virus in all secretions
  • venereal, in-utero, milk, colostrum
  • transmitted by insects (if uninterupted, then no transmission)
35
Q

Equine Infectious Anemia Virus pathogenesis

A
  • initially infects monocytes, but no replication
  • monocytes enter tissue and become macrophages, replication begins
  • virus spreads to lymphocytes
  • virus in blood is absorbed onto RBCs
  • antibodies mediate lysis of RBCs, resulting in anemia and thrombocytopenia
36
Q

Equine Infectious Anemia Virus clinical signs

A
  • anemia, lethargy, weight loss, fever
  • enlarged spleen, swollen belly and legs
  • depression, decreased athletic performance

Virology (15 decks)

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