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Chapter 13 Flashcards

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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
What are the endogenous gammaretroviruses?
Endogenous feline leukemia virus
26
What are the four subgroups of FeLV?
A, B, C, and T
27
Which FeLV subgroup is contagious and transmitted horizontally from cat to cat?
A
28
Which FeLV subgroup is a genetic variant of subgroup A?
T
29
How did FeLV subgroups B and C evolve?
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
30
Pathogenicity of subgroups _ and _ are higher than subgroup B.
B and C
31
Which FeLV subgroup is mainly associated with malignancies?
B
32
Which FeLV subgroup is mainly associated with non-regenerative anemia?
C
33
Which FeLV subgroup is found in all naturally infected cats?
A
34
Which FeLV subtype is the only subtype to be transmitted from cat to cat?
A
35
Subgroup B is found in __ % of naturally infected cats.
50
36
Subgroup C is found in _% of naturally infected cats.
1
37
Which FeLV subgroup is highly cytopathic and contains two different cell receptors?
T
38
Which FeLV subgroup is responsible for causing immunosuppression?
T
39
What are the 3 most clinically important antigens found in the virion of FeLV?
gp70, p15E, and p27
40
What is gp70?
The major antigen expressed in the viral envelope of FeLV, mediates cell-attachment, carries neutralizing determinants
41
How many subtypes does gp70 have and which is the most common?
3 -A
42
What is p15E?
Non-glycosylated envelope transmembrane protein; its role in immunosuppression is controversial
43
What is p27?
core protein
44
Which FeLV protein does ELISA and IFA detect?
p27
45
True or False: FOCMA is encoded by FeLV.
False: It is not encoded by a virus, but is expressed on cells transformed by FeLV
46
How is FeLV transmitted predominantly?
saliva
47
What are the possible outcomes to infection with FeLV?
1. Immunity 2. Persistent infection 3. Sick - Neoplasia, degenerative disease, or immunosuppression 4. Latent infection
48
What are the FeLV-related disorders?
Neoplasia, anemia, immune complexes, reproductive problems, enteritis, neuropathy, osteochondromatosis, fading kitten syndrome
49
What are the 4 diagnostic approaches to FeLV infection?
ELISA, IFA, PCR, FOCMA
50
What is the interaction between FeLV and FeSV?
FeSV is a replication defective virus and requires FeLV to function as a helper virus
51
What virus causes enzootic bovine leukosis?
Bovine leukemia virus
52
What type of retrovirus is bovine leukemia virus?
an exogenous deltaretrovirus
53
What cell type does bovine leukemia virus infect?
B lymphocytes
54
How is bovine leukemia virus transmitted horizontally?
via rectal palpation, dehorning, and close contact with a herd
55
What percentage of calves are born with bovine leukemia virus?
<10%
56
What inactivates bovine leukemia virus?
pasteurization
57
What three lentiviruses replicate in both monocytes and lymphocytes?
Human immunodeficiency virus (HIV) Simian immunodeficiency virus Feline immunodeficiency virus
58
What four lentiviruses replicate in monocytes and macrophages?
Visna/Maedi/OPP group Caprine arthritis-encephalitis (CAE) Equine Infectious anemia (EIA) Bovine immunodeficiency virus (BIV)
59
What are the important features of Lentiviruses?
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
What cell types does FIV infect?
macrophages and lymphocytes
61
Where can FIV disseminate?
CNS system and lymphoid organs
62
What can result from FIV CNS dissemination?
alteration in neuronal metabolism, neuronal toxicity, and behavioral changes
63
What can result from FIV lymphoid dissemination?
Increased viremia | Infection may be contained by adequate immune response or there could be progressive immune dysfunction
64
What clinical syndromes are associated with FIV?
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
How is FIV transmitted horizontally?
mainly bite and fight wounds
66
How is FIV transmitted vertically?
In utero or via milk
67
What are the three forms of equine infectious anemia (EIA)?
Acute, chronic, or inapparent
68
How would you characterize acute EIA?
High levels of virus replication, may result in death in 1-4 weeks post infection
69
How would you characterize chronic EIA?
Recurrent cycles of fever, viremia, and thrombocytopenia | Anemia, edema, glomerulonephritis
70
How would you characterize inapparent EIA?
seropositive, no clinical signs
71
What is the major impediment to development of effective vaccines for EIA?
Genetic mutations arise in genes encoding structural proteins and antigenic variation provides a periodic escape of virus from neutralizing antibody and CTL
72
How is EIA transmitted?
Biting flies and blood contaminated fomites
73
What diseases does Caprine arthritis-enecephalitis virus cause (CAEV)?
Arthritis, encephalitis, mastits, interstitial pneumonia
74
True or False: CAEV persists for line in the infected goat
true
75
What is the major route of transmission of CAEV?
major route of transmission is from does kid in colostrum and milk
76
What are the clinical prestentations of Ovine Progressive Pneumonia Virus (OPPV)?
Encephalitis, arthritis, and mastitis
77
What is Visna?
neurological manifestion of OPPV infection
78
What do we need to know about bovine immunodeficiency virus
there is a worldwide seroprevalence but the clinical significance is not clear

Virology (13 decks)

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