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Virology > Virus/cell interactions 2 > Flashcards

Virus/cell interactions 2 Flashcards

1
Q

What did Peyton Rous do?

A

took muscle cancer from a chicken,cultured it and ground it up, then injected it in another chicken. Chicken had cancer.This showed virus was responsible

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2
Q

What virus did Peyton Rous isolate,culture and put into a chicken?

A

RSV-Rous sarcoma virus

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3
Q

define sarcoma

A

malignant tumor of connective or other nonepithelial tissue.

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4
Q

define fibrosarcoma

A

a sarcoma in which the predominant cell type is a malignant fibroblast.

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5
Q

how does a transforming virus work? what is the proto oncogene captured by?

A

when a cellular proto oncogene is captured by insertion into the viral genome during viral replication

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6
Q

what are most oncogene containing viruses?

A

retroviruses

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7
Q

What is RSV Rous sarcoma virus an example of?

A

a transforming retrovirus

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8
Q

why is RS Rous sarcoma virus a transforming virus?

A

it has captured an oncogene that makes sarcoma

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9
Q

what is an oncogene?

A

a gene that in certain circumstances can transform a cell into a tumor cell

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10
Q

if oncogene badly regulated what does it lead to?

A

cancer

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11
Q

what is RSV related to?

A

HIV

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12
Q

what are viruses related to RSV but not containing oncogenes called?

A

ALVs

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13
Q

explain ALVs wrt replication and cell transformation

A

virus replication but no transformation of cell

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14
Q

explain RSV wrt replication and cell transformation

A

virus replication and DOES transform cells

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15
Q

what do ALV and RSV have in common?

A

both infect chicken cells

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16
Q

what are the 2 ways retroviruses can cause cells to transform?

A

a) if they contain oncogene they can cause cancer

b) if they alter expression of cellular oncogenes they can also cause cancer

17
Q

is cellular transformation by DNA viruses always helpful to the virus?

A

No in fact it is often not helpful

18
Q

what is an example of a DNA virus that transforms cells?

A

Papillomavirus

19
Q

why is the transformation of the papillomavirus bad?

A

viral proteins are required for controlled replication of the virus (as benign growth/wart) But if the virus is accidentally integrated into the host chromosome this can lead to unbalanced production of viral replication proteins which can lead to a malignant tumour and non production of the whole virus(doesn’t do virus any good)

20
Q

what does papillomavirus need for controlled replication?

A

viral proteins

21
Q

how is the papillomavirus genome organised?

A

In an episome (chromosome as circular episome)

22
Q

what is the MMTV?

A

mouse mammary tumour virus

23
Q

why are induced defenses not always present?

A

although they are more specific they are not as efficient for the cell and we only want them when the virus is around

24
Q

what is an example of a an induced response?

A

Interferons (IFNs), a group of signaling proteins made and released by host cells in response to the presence of pathogens, such as viruses, bacteria, parasites, or tumor cells. In a typical scenario, a virus-infected cell will release interferons causing nearby cells to heighten their anti-viral defenses.

25
Q

why is combination therapy good?

A

targets multiple points of replication cycle in virus, now HIV treatment lasts lifespan

26
Q

what state do interferons induce?

A

“viral state”

27
Q

What things do inteferons activate? (4)

A

1) transcription inhibitor
2) translation inhibitor
3) protein processing inhibitor
4) virus maturation inhibitor

28
Q

what is TIP?

A

translation inhibitory protein`

29
Q

How does TIP help immune system?

A

checks CAP on DNA to make ribosome more picky and slower

30
Q

How has Influenza counteracted TIP?

A

has cap snatching RNA so steals CAP from host genome and sticks onto virus.

31
Q

what is are 2 examples of a non induced response?

A

a) APOBEC35

b) TRIM5

32
Q

what does APOBEC3G do?

A

defends against retroviruses by deaminating c–>u this causes HYPERMUTATION therefore the dna synthesized is degraded

33
Q

What does APOBEC3G cause in the DNA?

A

HYPERMUTATION as changes c–> u

34
Q

How a virus overcome APOBEC3G?

A

HIV has aquired vif

(viral infectivity factor) gene that stopes APOBEC3G

35
Q

what is VIF?

A

viral infectivity factor

36
Q

what is TRIM5 thought to do?

A

act against uncoating of

viruses by binding to capsid proteins

37
Q

What does TRIM5 alpha in chimpanzees do and what does this tell us about our past?

A

Trim5 alpha blocks HIV infections so we could have possibly been able to block HIV infections in the past too if our concestor shared TRIM5alpha

38
Q

what two examples illustrate viruses overcoming our responses?

A

Influenza - RNA cap snatching

Vif protein in HIV against APOBEC3G

Virology (6 decks)

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