Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Infection and Immunity > Retroviruses > Flashcards

Retroviruses Flashcards

1
Q

what type of genome does the Rous sarcoma has?

A

RNA genome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is Crick’ “Central Dogma”?

A

“once information has got into a protein it can’t get out again”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is the Rous sarcoma virus replication dependent on?

A

DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what effects does Actinomycin D has on RNA synthesis?

A

Actinomycin D inhibits transcription and hence RNA synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what inhibits virus growth?

A

Actinomycin D

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what route did the effects of actinomycin D in sarcoma suggested?

A

RNA -> DNA -> RNA -> Protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is the provirus hypothesis?

A

the provirus of Rous sarcoma is a region of DNA homologous with viral RNA stably integrated into the molecule of cellular DNA in the nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is used to fight against HIV?

A

reverse transcriptase inhibitors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is the viral RNA dependent on?

A

DNA polymerase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what does the reverse transcriptase do?

A

turns RNA back to DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what are the subfamilies in the family retroviridae?

A

orthoretrovirinae and spumaretrovirinae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

how are retroviruses transmitted?

A

transmission typically via close contact (oronasal, sexual, blood-borne)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what protects the retrovirus?

A

a lipid envelope

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

why does the retrovirus have an envelope?

A

because it is susceptible to desiccation and detergents (that’s why the envelope has lipids)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what are the key features of retroviruses?

A
  • two copies of RNA genome in each viral particle
  • reverse transcribe RNA to DNA
  • DNA “provirus” integrates into cellular DNA
  • establish persistent infections
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what does the “gag” gene encode in the retrovirus genome?

A

core structural proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what does the “pol” gene encode in the retrovirus genome?

A
  • enzymes for replication
  • reverse transcriptase
  • integrase
  • protease
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what does the “env” gene encode in the retrovirus genome?

A

envelope glycoproteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

how do retroviruses infect cells?

A

by binding to a cell surface molecule called the receptor

- it binds to a nuclear pore and once it binds it starts replicating

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what is necessary for a productive viral life cycle?

A

integration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

where do simple retroviruses (e.g. FeLV) integrate?

A

in dividing cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

where can lentiviruses (e.g. HIV) integrate?

A

in non-dividing cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what is integration?

A

the retroviral genome integrates into the cellular DNA and becomes part of the host

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

how much of the human genome is derived from ancestral retrovirus infections?

A

8.3%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
what does integration do?
maximises the chance of viral transmission
26
which retroviruses integrate?
all
27
how does the retroviral assembly work?
- RNA makes a poliprotein (single long protein? - sticks under membrane - bends the membrane - becomes more circular - protein inserted in this new molecule - has to be cut off from membrane - forms an immature molecule - then matures
28
where do some of the retroviruses assemble?
at the pericentriolar region of the nucleus, the fully assembled particles then migrates to the cell surface
29
is there any vaccine against retroviruses that is effective?
only the feline leukaemia (FeLV) vaccine works
30
what does the FeLV cause?
immunosuppression, tumours, anaemia
31
which are the subgroups of FeLV?
three subgroups: A, B, C, classified according to the viral envelope glycoprotein
32
from where has the FeLV-A subgroups been isolated?
from all infected cats
33
where are the FeLV-B and C subgroups generated?
within the host
34
how viral is FeLV?
cats may clear the virus or become persistently infected
35
what do retroviruses establish?
persistent infections
36
what does the bovine leukaemia virus cause?
zoonotic bovine leukosis
37
what does the bovine leukaemia virus infect?
B lymphocytes
38
are there free virus in the blood in bovine leukosis?
no
39
what doe persistently infected cattle produce?
antibodies
40
what does viral tax protein trans activates?
cellular genes
41
how is bovine leukaemia virus transmitted?
via infected cells e.g. milk, blood
42
how can bovine leukaemia virus be transmitted?
vertically or horizontally
43
which are the oncogenic retroviruses?
- alpha avian leukosis viruses (ALV) - beta Jaagsiekte sheep retrovirus (JSRV) - gamma feline leukaemia virus (FeLV) - delta bovine leukaemia virus (BLV)
44
what are the mechanisms of retroviral oncogenesis?
- oncogene capture and transduction - insertional activation - insertion leading to truncation - insertion leading to gene inactivation - other mechanisms
45
how can retroviral proteins lead to tumour formation?
they can deregulate normal cellular metabolism and lead to tumour formation
46
what are the effects of an infection with oncogenic virus in the cell?
- lossof contact inhibition - increased saturation density - increased growth rate - anchorage-independent growth - tumorigenic in appropriate hosts
47
what causes OPA?
a retrovirus called JSRV
48
where does JSRV replicate?
only in type II pneumocytes and club cells
49
what are club cells?
bronchiolar exocrine cells
50
what does replication lead to?
to transformation of every cell
51
what does the viral Env switches on?
signals for cell division and activates cell signalling pathways
52
what is the incubation period of Maedi-Visna Virus (MVV)?
approx. 2 years
53
what does MVV cause?
ovine progressive pneumonia
54
how is equine infectious anaemia virus (swamp fever) transmitted?
by bitting insects (horseflies)
55
what is associated with the emergence of viral emergents?
episodic pyrexia/illness
56
what are the treatments for swamp fever?
there are no treatment options
57
what is swamp fever related to?
immune complex formation, complement activation
58
what are the immunodeficiency-causing lentiviruses?
- feline immunodeficiency virus - human immunodeficiency virus - simian immunodeficiency virus
59
how many people are currently infected by HIV?
35 million people
60
how many deaths in sub-Saharan Africa are caused by AIDS?
76%
61
where do the endogenous retroviruses (ERVs) genome persists?
in host DNA
62
what does the integration of the retrovirus into the germ cellular DNA cause?
vertical transmission of viral DNA to offspring
63
what are ERVs?
transposable (mobile) genetic elements
64
are ERVs defective?
most of them, but not all
65
what do ERV-derived genes may provide to the host?
useful or essential functions to the host e.g. syncytin in placental morphogenesis
66
what is the fusion of the trophoblast cell layer into the continuous multinucleate syncytiotrophoblast associated with?
implantation of the embryo
67
what mediates the trophoblast cell fusion?
the expression of the HERV-W Env (envelope)
68
for what have retroviral vectors been developed?
gene therapy
69
what may the integration of DNA provirus lead to?
development of cancer
70
what is the integration of DNA provirus used for?
exploited for gene therapy

Infection and Immunity (23 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions