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Virology > Chapter 13 > Flashcards

Chapter 13 Flashcards

1
Q

What are the key features of retrovirus replication?

A
  1. Entry via membrane fusion or receptor mediated endocytosis
  2. High error rate of reverse transcriptase
  3. Stable integration into host genome
  4. Release from cell via budding
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2
Q

What is a provirus?

A

A DNA copy of genomic RNA, which integrates into the hosts genome

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3
Q

What are the four main retroviral genes?

A

LTR, GAG, POL, and ENV

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4
Q

What does LTR do?

A

controls the expression of viral genes

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5
Q

What does GAG encode for?

A

Encodes core proteins

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6
Q

What does POL encode for?

A

Encodes polymerase and viral enzymes

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7
Q

What does ENV encode for?

A

Encodes envelope proteins

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8
Q

What are the 7 principle retroviral genera?

A
  1. Alpharetrovirus
  2. Betaretrovirus
  3. Gammaretrovirus
  4. Deltaretrovirus
  5. Episilonretrovirus
  6. Lentivirus
  7. Spumavirus
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9
Q

What are the three key features of retrovirus replication that contribute to transformation?

A
  1. Reverse transcription of (+) ssRNA into dsDNA
  2. Integration of dsDNA into host cell chromosome
  3. Transcriptional regulatory sequences in the viral long terminal repeat
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10
Q

What three genera of retroviruses can cause transduction of proto-oncogenes?

A

alpha, beta, and gamma

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11
Q

What is cis-activation in the context of retroviral oncogenesis?

A
  • The retrovirus genome integrates near a cellular oncogene
  • The transcriptional expression of proto-oncogene is under the control of the virus LTR and no longer the control of the cell
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12
Q

What is trans-activation in the context of retroviral oncogenesis?

A
  • The retrovirus encodes a protein that activates expression of cellular proto-oncogene
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13
Q

What retrovirus genuses use cis-activation?

A

alpha, beta, and gamma

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14
Q

What retrovirus genuses use trans-activation?

A

delta

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15
Q

What are the two classes of avian alpharetroviruses and which is pathogenic?

A

Endogenous - non-pathogenic

Exogenous - pathogenic

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16
Q

What are the two forms of exogenous alpharetroviruses?

A

Replication competent and replication defective

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17
Q

Explain the concept of the helper virus.

A

Replication defective viruses have required an oncogene from a cellular oncogene so they are not able to replicate. Helper viruses are replication competent viruses. They aid replication defective viruses by providing the function of the missing gene.

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18
Q

What five disease forms does Avian Leukosis Virus cause?

A
  1. Erythroblastosis
  2. Myeloblastosis
  3. Myelocytomatosis
  4. Hemangioma
  5. Connective tissue tumors
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19
Q

What five clinical syndromes does Avian Leukosis Virus cause?

A
  1. Lymphoid leukosis
  2. Osteopetrosis
  3. Erythroblastosis
  4. Myeloblastosis
  5. Others: connective tissue tumors, hemangiomas, myelocytomatosis
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20
Q

What genus does Jaagsiekte sheep retrovirus belong in?

A

betaretrovirus

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21
Q

What does Jaagsiekte sheep retrovirus cause?

A

Ovine pulmonary adenomatosis

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22
Q

What clinical syndrome/disease does Ovine pulmonary adenomatosis cause?

A

bronchioalveolar carcinoma of sheep

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23
Q

What are the two broad groups gammaretroviruses and what species are involved?

A

Exogenous and endogenous viruses

cats

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24
Q

What are the exogenous gammaretroviruses?

A

Feline leukemia viruses

Feline Sarcoma virus

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25
Q

What are the endogenous gammaretroviruses?

A

Endogenous feline leukemia virus

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26
Q

What are the four subgroups of FeLV?

A

A, B, C, and T

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27
Q

Which FeLV subgroup is contagious and transmitted horizontally from cat to cat?

A

A

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28
Q

Which FeLV subgroup is a genetic variant of subgroup A?

A

T

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29
Q

How did FeLV subgroups B and C evolve?

A

They evolved de novo in FeLV-A infected cats by mutation and recombination between FeLV-A and cellular or endogenous retroviral sequences contained in normal feline DNA

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30
Q

Pathogenicity of subgroups _ and _ are higher than subgroup B.

A

B and C

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31
Q

Which FeLV subgroup is mainly associated with malignancies?

A

B

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32
Q

Which FeLV subgroup is mainly associated with non-regenerative anemia?

A

C

33
Q

Which FeLV subgroup is found in all naturally infected cats?

A

A

34
Q

Which FeLV subtype is the only subtype to be transmitted from cat to cat?

A

A

35
Q

Subgroup B is found in __ % of naturally infected cats.

A

50

36
Q

Subgroup C is found in _% of naturally infected cats.

A

1

37
Q

Which FeLV subgroup is highly cytopathic and contains two different cell receptors?

A

T

38
Q

Which FeLV subgroup is responsible for causing immunosuppression?

A

T

39
Q

What are the 3 most clinically important antigens found in the virion of FeLV?

A

gp70, p15E, and p27

40
Q

What is gp70?

A

The major antigen expressed in the viral envelope of FeLV, mediates cell-attachment, carries neutralizing determinants

41
Q

How many subtypes does gp70 have and which is the most common?

A

3 -A

42
Q

What is p15E?

A

Non-glycosylated envelope transmembrane protein; its role in immunosuppression is controversial

43
Q

What is p27?

A

core protein

44
Q

Which FeLV protein does ELISA and IFA detect?

A

p27

45
Q

True or False: FOCMA is encoded by FeLV.

A

False: It is not encoded by a virus, but is expressed on cells transformed by FeLV

46
Q

How is FeLV transmitted predominantly?

A

saliva

47
Q

What are the possible outcomes to infection with FeLV?

A
  1. Immunity
  2. Persistent infection
  3. Sick - Neoplasia, degenerative disease, or immunosuppression
  4. Latent infection
48
Q

What are the FeLV-related disorders?

A

Neoplasia, anemia, immune complexes, reproductive problems, enteritis, neuropathy, osteochondromatosis, fading kitten syndrome

49
Q

What are the 4 diagnostic approaches to FeLV infection?

A

ELISA, IFA, PCR, FOCMA

50
Q

What is the interaction between FeLV and FeSV?

A

FeSV is a replication defective virus and requires FeLV to function as a helper virus

51
Q

What virus causes enzootic bovine leukosis?

A

Bovine leukemia virus

52
Q

What type of retrovirus is bovine leukemia virus?

A

an exogenous deltaretrovirus

53
Q

What cell type does bovine leukemia virus infect?

A

B lymphocytes

54
Q

How is bovine leukemia virus transmitted horizontally?

A

via rectal palpation, dehorning, and close contact with a herd

55
Q

What percentage of calves are born with bovine leukemia virus?

A

<10%

56
Q

What inactivates bovine leukemia virus?

A

pasteurization

57
Q

What three lentiviruses replicate in both monocytes and lymphocytes?

A

Human immunodeficiency virus (HIV)
Simian immunodeficiency virus
Feline immunodeficiency virus

58
Q

What four lentiviruses replicate in monocytes and macrophages?

A

Visna/Maedi/OPP group
Caprine arthritis-encephalitis (CAE)
Equine Infectious anemia (EIA)
Bovine immunodeficiency virus (BIV)

59
Q

What are the important features of Lentiviruses?

A

Lentivirus genomes contain a number of genes that mediate complex virus-host interactions and contribute to persistence and pathogenesis
Lentiviruses have a high rate of genetic variation

60
Q

What cell types does FIV infect?

A

macrophages and lymphocytes

61
Q

Where can FIV disseminate?

A

CNS system and lymphoid organs

62
Q

What can result from FIV CNS dissemination?

A

alteration in neuronal metabolism, neuronal toxicity, and behavioral changes

63
Q

What can result from FIV lymphoid dissemination?

A

Increased viremia

Infection may be contained by adequate immune response or there could be progressive immune dysfunction

64
Q

What clinical syndromes are associated with FIV?

A

Chronic stomatitis, severe gingivitis, chronic upper respiratory tract disease, lymphadenopathy, mild pyrexia, depression, and leukopenia, wasting, anemia, chronic skin disease, chronic, diarrhea, neurological signs

65
Q

How is FIV transmitted horizontally?

A

mainly bite and fight wounds

66
Q

How is FIV transmitted vertically?

A

In utero or via milk

67
Q

What are the three forms of equine infectious anemia (EIA)?

A

Acute, chronic, or inapparent

68
Q

How would you characterize acute EIA?

A

High levels of virus replication, may result in death in 1-4 weeks post infection

69
Q

How would you characterize chronic EIA?

A

Recurrent cycles of fever, viremia, and thrombocytopenia

Anemia, edema, glomerulonephritis

70
Q

How would you characterize inapparent EIA?

A

seropositive, no clinical signs

71
Q

What is the major impediment to development of effective vaccines for EIA?

A

Genetic mutations arise in genes encoding structural proteins and antigenic variation provides a periodic escape of virus from neutralizing antibody and CTL

72
Q

How is EIA transmitted?

A

Biting flies and blood contaminated fomites

73
Q

What diseases does Caprine arthritis-enecephalitis virus cause (CAEV)?

A

Arthritis, encephalitis, mastits, interstitial pneumonia

74
Q

True or False: CAEV persists for line in the infected goat

A

true

75
Q

What is the major route of transmission of CAEV?

A

major route of transmission is from does kid in colostrum and milk

76
Q

What are the clinical prestentations of Ovine Progressive Pneumonia Virus (OPPV)?

A

Encephalitis, arthritis, and mastitis

77
Q

What is Visna?

A

neurological manifestion of OPPV infection

78
Q

What do we need to know about bovine immunodeficiency virus

A

there is a worldwide seroprevalence but the clinical significance is not clear

Virology (13 decks)

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