3.8 (1) Retroviruses Flashcards

1
Q

retroviruses:
- genome
- enveloped/nonenveloped

A

2 copies of ssRNA
enveloped

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2
Q

what type of cells do retroviruses infect

A

CD4+ lymphocytes

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3
Q

what is unique about replication machinery of retroviruses

A

they have reverse transcriptase (RNA -> DNA)

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4
Q

what is the role of reverse transcriptase

A

after infection, RT converts the RNA genome into dsDNA, which then integrates into the host genome

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5
Q

how are retrovirus genes transcribed and translated

A

from the genome integrated viral DNA

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6
Q

what does the following encode:
- gag
- pro
- env
- pol

A

gag: structural proteins
pro: proteases
env: envelope
pol: polymerase

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7
Q

what are the 3 functions of the polymerase of retroviruses

A

1) RNA-dependent DNA polymerase (reverse transcriptase)
2) DNA dependent DNA polymerase
3) RNAse

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8
Q

what are the 5 genera of retroviruses

A

alpharetrovirus, betaretrovirus, deltaretrovirus, gammaretrovirus, lentivirus

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9
Q

name an important alpharetrovirus

A

avian leukosis virus (ALV)

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10
Q

name an important deltaretrovirus

A

bovine leukemia virus (BLV)

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11
Q

name an important gammaretrovirus

A

feline leukemia virus (FeLV)

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12
Q

name an important lentivirus

A

feline immunodeficiency virus (FIV)

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13
Q

T/F lymphoma and lymphosarcoma are synonymous

A

T

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14
Q

leukosis is the basis of

A

leukemia

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15
Q

________ is the basis of leukemia

A

leukosis

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16
Q

what is leukosis

A

neoplastic proliferation of leukocyte-forming tissue

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17
Q

avian alpharetroviruses can be classified as (3)

A

exogenous replication competent, exogenous replication incompetent, endogenous avian leukosis viruses

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18
Q

describe exogenous replication competent viruses

A
  • transmitted horizontally or congenitally
  • usually slow tumor development because they do not have their own oncogenes
  • tumors arise from insertion mutations
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19
Q

describe exogenous replication incompetent viruses

A
  • have an oncogene but lose viral proteins
  • require a helper virus for replication
  • rarely transmitted
  • rapidly transform because of the oncogene
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20
Q

describe endogenous avian leukosis viruses

A
  • proviruses in somatic and germline genome
  • transmitted genetically only
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21
Q

where is avian leukosis virus commonly seen and where is it rarely seen (what type of flocks)

A

commonly seen in backyard chickens, low occurence in commercial flocks

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22
Q

does avian leukosis virus have a fast or slow rate of tumor development

A

slow

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23
Q

what are the two syndromes seen in a chicken with avian leukosis virus

A
  • enlarged long bones (wings, legs)
  • tumors in liver, kidney, spleen
24
Q

what is an important differential for a chicken that may have avian leukosis virus

A

mareks disease

25
Q

avian leukosis virus:
- detection of viral antigen is via:
- detection of antibody in serum is via:
- detection of nucleic acid is via:

A
  • ELISA
  • ELISA
  • PCR
26
Q

it is important to distinguish if a chicken has Mareks or Avian Leukosis virus because

A

Marek’s has a vaccine but Avian Leukosis does not

27
Q

what is the name of the disease caused by BLV

A

enzootic bovine leukosis

28
Q

cow herds require to be free of what retrovirus for export

A

BLV

29
Q

how many dairy cattle in the USA are infected with BLV; of these how many tend to develop clinical disease

A

25%; few

30
Q

T/F BLV is highly transmissible

A

F

31
Q

how is BLV transmitted

A

mainly by blood or tissue containing infected lymphocytes; rarely by insects as mechanical vectors

32
Q

BLV infects primarily _________, which is mediated by the viral oncoprotein _______

A

B lymphocytes; Tax

33
Q

what happens to animals infected with BLV

A

lymphosarcoma of B cell origin in a variety of tissues (lymph node, abomasum, heart, spleen, kidneys, uterus, meninges, brain)

34
Q

what signs are seen in an animal with BLV…. what is seen on postmortem?

A

enlarged pre-femoral and retropharyngeal lymph nodes; tumors in uterus and on thoracic vertebrae

35
Q

how is BLV diagnosed (2)

A
  • ELISA
  • PCR
36
Q

what is the treatment for BLV

A

no treatment… animals are sent to slaughter

37
Q

T/F there is a vaccine for BLV

A

F

38
Q

what type of virus is FeLV

A

exogenous gammaretrovirus

39
Q

what determines the pathogenicity of FeLV and what 4 antigenic types does it give rise to

A

pathogenicity is determined by envelope proteins
subtypes:
- A
- B
- C
- T

40
Q

Describe the following:
- FeLV-B:
- FeLV-C:
- FeLV-T:

A

B: neoplasia
C: anemia
T: immunosuppression (destruction of T cells)

41
Q

what 4 disorders does FeLV cause

A

1) neoplasia
2) neurologic disorders
3) immunosuppression
4) reproductive failure

42
Q

how is FeLV transmitted

A

saliva and tears (friendly cat disease)

43
Q

is FeLV usually an acute or chronic disease

A

chronic

44
Q

there are multiple disease trajectories of FeLV, which are influenced by (5)

A
  • age
  • genetics (cat)
  • environment
  • virus
  • concurrent infection
45
Q

what are the 3 types of infection that can develop in a cat with FeLV

A

1) abortive
2) regressive
3) progressive

46
Q

describe the following:
1) abortive FeLV
2) regressive FeLV
3) progressive FeLV

A

1) no viremia
2) viremia that is cleared
3) persistent viremia

47
Q

how is FeLV diagnosed:
- antigen detection by_______
- nucleic acid detection by _______

A

ELISA; PCR

48
Q

interpret the following FeLV test results:
1) ELISA - and PCR -
2) ELISA - and PCR +
3) ELISA + and PCR -
4) ELISA + and PCR +

A

1) abortive
2) and 3) regressive
4) progressive

49
Q

interpret the following FeLV test results:
1) high levels of provirus DNA and antigen
2) low levels of provirus DNA and antigen

A

1) progressive infection
2) regressive infection

50
Q

T/F antiretroviral compounds have high success at treating FeLV

A

F

51
Q

what type of virus is FIV and what does this mean about the course of infection

A

lentivirus; slow infection for life

52
Q

T/F FIV is endemic

A

T

53
Q

how is FIV shed

A

saliva

54
Q

what cats are the greatest risk of FIV

A

free-roaming, male, older cats

55
Q

what is a common dual infection in cats

A

FIV and FeLV

56
Q

what are the 3 stages of FIV

A

1) acute
2) subclinical
3) terminal

57
Q

terminal FIV infection is characterized by

A

immunodeficiency due to a loss of CD4+ lymphocytes -> opportunistic bacterial and fungal infections