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Virology > Retroviruses > Flashcards

Retroviruses Flashcards

1
Q

What important enzyme is found in all retroviruses?

A

reverse transcriptase, RNA-dependent DNA polymerase

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2
Q

genome of retroviruses

A

two copies of ssRNA (+)

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3
Q

Which enzyme is responsible for integrating the retrovirus genome into the host genome?

A

integrase

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4
Q

two subfamiles of retroviridae

A

orthoretrovirinae and spumaretrovirinae

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5
Q

T/F Type B retroviruses have a round centrally positioned inner core

A

F: eccentrically positioned

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6
Q

T/F retro virions are resistant to UV or X rays

A

T

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7
Q

What does the gag gene encode

A

capsid, nucleocapsid, matrix

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8
Q

What does pol encode?

A

RT and IN

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9
Q

What does env gene encode?

A

surface and transmembrane envelope proteins

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10
Q

What does the pro gene encode?

A

protease

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11
Q

What is the role of Nef protein?

A

essential for replication in target hosts; may downregulate CD4 or alter activation status of target cells

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12
Q

What type of morphology do alpharetroviruses have?

A

Type C: concentric core

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13
Q

What virus represents alpharetroviruses?

A

avian leucosis and sarcoma virus (ALSV)

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14
Q

T/F exogenous retroviruses are those viruses included in the genome of most animals

A

F: endogenous

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15
Q

T/F exogenous retroviruses are transmitted vertically

A

F : horizontally

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16
Q

What morphology are betaretroviruses?

A

type B (eccentric core) or D (cylindrical core)

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17
Q

What is an important betaretrovirus?

A

mouse mammary tumor virus (MMTV)

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18
Q

What type of morphology do gammaretroviruses have?

A

C type

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19
Q

Important gammaretrovirus?

A

FLV

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20
Q

Morphology of deltaretroviruses?

A

type C

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21
Q

example of a deltaretrovirus?

A

bovine leukemia virus

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22
Q

Which retro genus has rex and tax regulatory genes?

A

deltaretroviruses -> control synthesis and processing of viral RNA

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23
Q

Are there any known endogenous deltaretroviruses?

A

no

24
Q

What is an example of an epsilonretrovirus?

A

Walleye dermal sarcoma virus

25
Q

Important lentiviruses?

A

HIV, caprine arthritis-encephalitis virus, visna virus

26
Q

Important spumavirus?

A

human foamy virus

27
Q

receptors for retroviruses

A

alpha: membrane anchored glycoprotein
beta: transferrin receptor tfr-1
gamma: GLVR1 or FeLIX
delta: AP-3 complex
lenti: CD4

28
Q

Where does uncoating occur?

A

cytoplasm

29
Q

Where does integration occur?

A

nucleus

30
Q

Which end of virla dsDNA is processed by IN?

A

3’

31
Q

Is integration site specific?

A

no, but transcriptionally active preferred

32
Q

When is viral DNA called a provirus?

A

after integration into the host cell chromosome has completed

33
Q

What happens to produced viral RNA?

A

spliced and transported to cytoplasm

34
Q

What are the two pools of viral mRNA in cytoplasm of infected cell?

A

full length : packaged into virions as viral RAN

spliced: express structural proteins (gag, pol, env)

35
Q

How are virions released?

A

budding from the cell membrane

36
Q

Which genus causes cell death?

A

lentivirus -> formation of syncytium and apoptosis

37
Q

What is necessary for acute transformation?

A

v-onc

38
Q

How do retroviruses cause chronic transformation?

A

intertion/mutation through random integration into genome of host

39
Q

Two forms of endogenous gammaretroviruses

A

enFeLV nad RD114 virus

40
Q

T/F prevalence of FeLV in individually kept cats is high

A

false 1%

41
Q

Where is FeLV shed in infected cats?

A

saliva, nasal secretions, feces, milk

42
Q

How is FeLV transmitted?

A

bites and mutual grooming

43
Q

T/F aged cats become resistant to FeLV infection

A

T

44
Q

What is the main determinant of pathogenicity in FeLV?

A

SU protein

45
Q

What tissue does FeLV have tropism to?

A

lymphoid tissue

46
Q

What is the effect of FeLV on T cells?

A

reduced the number of CD4 cells

47
Q

T/F Cats with FeLV have normal IgM levels

A

F: reduced IgM levels but normal IgG levels

48
Q

symptoms of FeLV

A

immunosuppression, anemia, lymphoma and leukemia

49
Q

Diagnosis of FeLV?

A

virus isolation in cell culture if the ultimate criterion (also p27 ELISA)

50
Q

What causes FIV?

A

lentivirus

51
Q

Why are lentiviruses called slow viruses?

A

long incubation period (up to 6 years)

52
Q

In what cells does FIV replicate?

A

CD4 mostly, also B cells and macs

53
Q

How is FIV transmitted?

A

deep bite wounds and scratches

54
Q

Can FIV be transmitted from mother to kittens during passage through birth canal?

A

yes occasionally

55
Q

clinical signs of FIV

A

poor coat, persistent fever, gingivitis, lethargy, upper resp infections

56
Q

treatment for FIV?

A

treated symptomatically, can’t eliminate the virus

57
Q

T/F If a cat has antibodies for FIV, it has the virus.

A

False - the vaccine will cause cats to be FIV antibody positive

Virology (16 decks)

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