DNA VIRUSES Clinical features and replicatio Flashcards

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1
Q

Why are the life cycles of DNA viruses interesting?

A
  • cause life-threatening human disease (oncogenic) e.g HBV and liver cancer and papilloma and cervical cancer)
  • therapeutic agents (anti-cancer) e.g adenovirus to treat head and neck cancer. Herpes simplex to treat solid tumours
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2
Q

When do viruses cause cancer?

A

-when their life cycle goes wrong (not a usual part of life cycle as it is a dead end for the virus)

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3
Q

What is the role of immunosurvellience?

A

important in recognition and destruction of transformed cells before they grow into tumours and important in controlling DNA virus infections

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4
Q

How long does it usually take after a virus for a cancer to develop?

A

10 years

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5
Q

Where do DNA viruses replicate?

A

in the nucleus (except pox)

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6
Q

What are the requirements for DNA viral replication?

A

virus encoded immediate early and early protein can induce:
-polymerase plus other factors (thymidine kinase)
-access to nucleotides
OR induce the host cell to express the polymerase

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7
Q

Where do the replication proteins come from?

A

For small DNA viruses:
-do not encode a whole genome replication system
-encode proteins that orchestrate the host
Large DNA viruses
-encode proteins in their genome

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8
Q

What are the roles of the viral early proteins?

A

Affect host functions that regulate growth:

  • stimulate cell proliferation
  • block cell death
  • orchestrate host cell so it supports virus genome replication
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9
Q

What is the role of early proteins E6 and E7?

A
  • deregulate cell growth control

- deregulate host tumour suppressor (Rb and p53) pathways

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10
Q

What is the role of E7?

A

host cell cycle regulators (suppresses Rb and pushed cells through S phase)

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11
Q

What us the role of E6?

A

cell regulators of apoptosis (prevent apoptosis even when cells have been programmed for cell death)

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12
Q

How could HPV case cancer?

A
  • E7 and E6 constantly targeting tumour suppressor genes so there is no way of monitoring genomic stability and preventing replication of cells with damaged DNA
  • higher risk of acquiring mutations
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13
Q

What makes up the HPV vaccine?

A

HPV16 L1 protein expressed in insect cells

-assembled into empty particles to form virus like particles

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14
Q

Why does the HPV vaccine not cure women with cervical cancer?

A

-prophylactic and not therapeutic vaccines

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15
Q

What does the HPV vaccine do?

A

blocks infection with HPV16 and HPV18 neutralising antibiotics

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