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PID > Oncogenic Viruses > Flashcards

Oncogenic Viruses Flashcards

1
Q

Which 4 gene types are damaged during oncogenesis?

A

Proto-oncogenes, tumour suppressor genes, regulating apoptosis, DNA repair

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2
Q

What are the oncogenic RNA viruses?

A

Oncoretroviruses

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3
Q

What are the oncogenic DNA viruses?

A

Papillomaviruses, herpesviruses

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4
Q

Which types of viruses cause leukaemias and lymphomas?

A

The alpha, beta, gamma, delta and epsilon viruses

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5
Q

What type of virus is HIV?

A

Lentivirus

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6
Q

Which species are affected by the alpha, beta, gamma, delta and epsilon viruses?

A

All veterinary

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7
Q

Why do retroviruses need close or blood contact?

A

Enveloped and unstable

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8
Q

What is the genome like in retroviruses?

A

ss +ve sense RNA with terminal repeat elements

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9
Q

Which type of virus has gag pol and env?

A

Retrovirus

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10
Q

What does gag do?

A

Structural

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11
Q

What does pol do?

A

Repliation enzymes

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12
Q

What does env do?

A

The envelopes

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13
Q

What happens to the DNA provirus in retroviruses?

A

Integrates into the host genome

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14
Q

What do the LTR of a retrovirus contain?

A

Enhancer elements

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15
Q

What can some acutely oncogenic viruses replace env with?

A

A host oncogene

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16
Q

What happens if you replace env with a host oncogene?

A

Replication defective

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17
Q

How can you become acutely oncogenic whilst remaining replication competent?

A

Just add and oncogene

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18
Q

What is the genome like in replication competent but weakly oncogenic viruses?

A

They have gag, pol and env with accessory ORFs which act as oncoproteins

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19
Q

Why can oncogenic retroviruses only affect replicating cells e.g. lymphoid, haematopoietic?

A

Can’t enter the nuclear membrane so the pre-integration complex must wait until cell division

20
Q

How are exogenous viruses transmitted?

A

Horizontal

21
Q

How are endogenous viruses transmitted?

A

Provirus in germline so vertical transmission

22
Q

How do some viruses encode v-onc?

A

Pick up a proto-oncogene and lose env/pol (take a highly active oncogene into the host cell)

23
Q

Which mutations can v-onc contain affecting proteins?

A

Alter normal protein function or regulation e.g. increase stability or cause constitutive activation

24
Q

What happens if v-onc fuses to gag?

A

Transports the oncoprotein to the cell membrane where it functions as a signal transporter.

25
Q

What is expression of v-onc like?

A

Not controlled as viral LTRs are strong and not affected by cellular regulation.

26
Q

What is replication like in viruses encoding v-onc?

A

Usually defective but can be competent.

27
Q

How do you get cis-activation of a cellular oncogene?

A

Provirus inserts close to c-onc and LTR acts as a promoter or enhancer

28
Q

What is replication and oncogenesis like in cis-activation of a cellular oncogene?

A

Weakly oncogenic and won’t transform in vitro, but competent for replication

29
Q

Why are tumours clonal in cis-activation of a cellular oncogene?

A

The cells all have one preferred integration site

30
Q

What is replication and oncogenesis like in trans-activation by an essential virus protein?

A

Weakly oncogenic, long incubation, replication competent

31
Q

Are the tumours clonal in in trans-activation by an essential virus protein?

A

Yes, but there is no preferred integration site

32
Q

What clinical signs are papillomaviridae assocaited with?

A

Warts

33
Q

Can you culture papillomavirus?

A

No

34
Q

Where are papillomavirus trophic for?

A

Squamous epithelium, as depend on terminal squamous epithelial cell differentiation to replicate.

35
Q

Are papillomavirus benign or malignant?

A

Benign usually

36
Q

What is the structure of papillomaviruses?

A

No envelope so stable

37
Q

What is genome of papillomaviruses like?

A

ds circular DNA, with early replication and late parts

38
Q

Which are the oncogenic gene products in papillomaviruses?

A

Early e.g. E5,6,7

39
Q

Which cell must be exposed for a papillomavirus to enter?

A

Basal stem cell

40
Q

What does early gene expression in papillomavirus push replication of?

A

Basal stem cells

41
Q

How does late gene expression begin in papillomaviruses?

A

Switch of cells into mature keratinocytes switches replication from plasmid to vegetational replication and late gene expression begins

42
Q

How does E6 interfere with cell cycle control?

A

Interacts with p53 and causes its degradation

43
Q

How does E7 interfere with cell cycle control?

A

Interacts with pRB and causes E2F-1 to always be released so the cell cycle continues

44
Q

What is the cofactor in CRPV skin carcinoma?

A

Methylcholanthrene

45
Q

Which type of herpesviruses are the oncogenic ones?

A

Gamma

46
Q

How do herpesviruses often become oncogenic?

A

Species jump

47
Q

What are two methods of activation of cellular oncogenes?

A

Cis or trans

PID (21 decks)

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