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4 CAN > 6 Oncogenic Viruses > Flashcards

6 Oncogenic Viruses Flashcards

1
Q

Name 3 viruses with known carcinogenic effects

A

Adenoviruses
Herpes viruses
Papilloma viruses

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2
Q

Which body decides which biological agents are classified as carcinogenic to humans?

A

IARC

International Agency for Research on Cancer (WHO)

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3
Q

How many types of HPV are deemed high risk because of their association with cancer development?

A

13

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4
Q

What is a viral direct carcinogen?

A

viral oncogenes directly contribute to cancer cell transformation

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5
Q

What is a viral indirect carcinogen?

A

viruses that cause cancer through chronic infection, inflmmation, and immunosuppression

lead ot carcinogenic mutations int eh host

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6
Q

What viruses are associated with indirect carcinogenesis?

A

HIV-1

Beta-HPV

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7
Q

How is Beta-HPV an inderect carcinogen?

A

blocks apoptosis
only cause carcinomas in UV exposed skin
blocking of apoptosis stops the repair and removal of cells damaged by UV light

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8
Q

How is HIV-1 an indirect carcinogen?

A

immunosuppression (opportunistic infections)
persistent immune activation causes chronic tissue damage
cell cycle deregulation
altered microenvironment

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9
Q

How does HIV-1 infection change the actions of co-infected viruses?

A

increases proliferation, increasing development of HPV associated cancers

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10
Q

A coinfection of what 2 viruses might cause Kaposi’s Sarcoma lesions

A

coinfection of KSHV and HIV-1

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11
Q

Why is it difficult to establish causality between viruses and cancers?

A

long latency
small % of infected develop tumour
complex pathogenesis
virus infection is one part of cancer development
no experimental animal models for human cancer

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12
Q

What proportion of the worldwide population is infected with EBV?

A

95%

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13
Q

What type of virus is EBV?

A

Herpes virus

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14
Q

What 2 cancers are associated with EBV?

A

Burkitt lymphoma

Nasopharyngeal cancer

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15
Q

What is Burkitt lymphoma associated with?

A

HBV malaria coinfection

MYC oncogene translocation to Ig enhancer (c-Myc deregulation)

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16
Q

What is Nasopharyngeal cancer associated with?

A

HBV

eating salted fish (nitrosamines)

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17
Q

who tend to get Kaposi sarcoma?

A

elderly Mediterranean men

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18
Q

What are the cancer causing types of HPV, what might they cause?

A

HPV 16
HPV 18

Cervical cancer
Vaginal and vulvar cancer

19
Q

What are the non-cancer causing forms of HPV?

What might they cause?

A

HPV6
HPV 11

Anogenital warts

20
Q

What are merkel cell carcinoma?

A

neuroectodermal tumour arising from mechanoreceptor Merkel cells in skin

21
Q

how long do people live with markel cell carcinoma?

A

9 months tops

22
Q

In 2008, it was found that which virus do merkel cell carcinomas contain?

A

Merkel Cell Polymavirus (MCPyV)

23
Q

What kind of carcinogen is HPV?

A

direct carcinogen

24
Q

How is cervical cancer caused by HPV changing?

Why?

A

decreasing

screening programmes

25
Q

Why are head and neck cancers caused by HPV increasing?

A

no screening programme

men more susceptible, and until recently weren’t vaccinated for HPV

26
Q

Which cells does HPV target?

A

mitotically active epithelial cells

pushes cells back into the cell cycle in the mid-epithelium

27
Q

Which oncoproteins does HPV induce the expression of?

A

E6

E7q

28
Q

What does E7 do?

A

directly inhibits Rb (stimulating G1-S phase progression)

degrades p53

29
Q

What is the Cyclin D cdk4.6 complex do, and what is it stimulated by?

A

phospharylates Rb (TSg)

stimulated by positive growth signals

30
Q

What are the effect of negative growth signals?

A

activation of p16 and p21, inhibiting cyclin D and cdk4.6 complex

31
Q

What does E6 do?

A

with E6AP sequesters p53 and degrades it

32
Q

What is the HBV vaccine?

A

purified hep B virus surface antigen (HBsAg)

33
Q

What makes the HBV vaccine so cheap?

A

it’s produced in huge batches in yeast

34
Q

How are cytological abnormalities in servix monitored?

A

Cervical smear

pap test

35
Q

when was cervicla cytology initiated?

A

1940s

36
Q

Where do lesions arise in cervical cancer?

A

squamo-columnar junction (SCJ)

37
Q

How can you reduce the incidence of CIN3+ like lesions?

A

HPV DNA testing and cytology

38
Q

What is done first, cytology or HPV DNA analysis?

A

HPV DNA

39
Q

What do we use for an HPV vaccine?

A

Virus-like particles, don’t contain HPV DNA

40
Q

What is Gardasil made from?

A

low risk HPV 6 and 11

41
Q

What is Gardasil used for?

A

genital warts

42
Q

Immunising against the top how many HPV carcinogens will decrease cervical cancer cases by 90%?

A

7

43
Q

how does HPV infect cells?

A

binds to heparin sulphate proteoglycan receptor
cleaved by purin enzyme
exposes another receptor binding site on L1 capsid protein

44
Q

how does antibody combat HPV?

A

bind the virus before it binds to the receptor and pruine cleavage occurs

4 CAN (21 decks)

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