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MIMM 324 > 15. Adenovirus 2 > Flashcards

15. Adenovirus 2 Flashcards

1
Q

what is pTP and its function?

A

pre-terminal protein which primes replication

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2
Q

describe the first phase of adenovirus replication (3 steps)

A
  1. pTP binds C on the end of DNA opposite of TP
  2. DNA pol starts replicating and displaces a ssDNA
  3. produces 1 dsDNA and 1 displaced ssDNA associated with DNA binding protein
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3
Q

describe the second phase of adenovirus replication (4 steps)

A
  1. the displaced ssDNA folds on itself at the inverted terminal repeats to make pan-handle structure
  2. a new pTP joins at a C opposite the TP
  3. DNA pol replicates and displaces the DNA binding protein
  4. produces another dsDNA
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4
Q

what happens once the genome is replicated? why?

A

late stage proteins can be made bc the late proteins are made from this new DNA

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5
Q

how many late proteins are there?

A

14

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6
Q

how many promoters are there for the late proteins?

A

1 major late promoter

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7
Q

how is it possible that there are 14 late proteins but 1 promoter? why does this let the virus be more efficient

A

ALTERNATIVE SPLICING!

can pack a lot of info into genome

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8
Q

describe the 5 steps of alternative splicing

A
  1. DNA transcribed to make 1 long RNA transcript
  2. transcript is poly-adenylated by cellular machinery at 5 different sites
  3. this gives different splice sites where transcript is spliced by cellular machinery
  4. tripartite leader is assembled
  5. many proteins can be made
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9
Q

does the machinery for poly-adenylation and splicing come from the virus or the cell?

A

cell!

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10
Q

where is the packaging sequence in the genome?

A

at the beginning

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11
Q

which mRNA have the tripartite leader?

A

tripartite leader is spliced onto every late mRNA

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12
Q

What do IVa2 and L2 52/55k do?

A

join to form ATPase driven motor

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13
Q

what is the role of L4 33K/100K?

A

viral chaperones/scaffolds for capsid assembly

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14
Q

can adenovirus capsid self-assemble?

A

no, requires chaperones and scaffold proteins

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15
Q

what is the role of E4 Orf4 and E3 11.6K?

A

to induce apoptosis once the viral life cycle has completed to leave the cell

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16
Q

how does E1A induce apoptosis?

A
  1. E1A binds Rb to allow E2F promoter to be active
  2. p14 ARF is produced
  3. p14 ARF binds MDM2 to stabilize p53
  4. stabilized p53 = apoptosis
17
Q

what is MDM2 function? how does p14 ARF affect it?

A

ubiquitinates p53 so it can be degraded

but p14 ARF binds MDM2 to prevent p53 from being degraded

18
Q

which oncogene inhibits p53?

A

E1B-55K

19
Q

how does E1B-55K inhibit p53? what does this result in?

A

sequesters p53 to inhibit it –> no apoptosis, cell can survive

20
Q

E1A and E1B vs E6 and E7

A

E1A = E7

E1B = E6

21
Q

what are oncolytic virus?

A

genetically engineered viruses that can induce immune system and kill tumour cells

22
Q

what is the other type of E1B?

A

E1B-19k

23
Q

what is the role of E1B-19K

A

inhibits Bax in mitochondria to inhibit apoptosis

24
Q

what does Bax do? how is it upregulated?

A

Bax forms pores at mitochondria to eventually induce apoptosis

upregulated by p53

25
Q

do E1B-55K and E1B-19K work together or is only 1 used?

A

both work together to maximize inhibition of apoptosis

26
Q

what type of RNA is VA RNA?

A

non-coding RNA

27
Q

what are the 3 functions of VA RNA?

A
  1. inhibit PKR activation
  2. block nuclear export of pre-mRNAs
  3. inhibit dicer
28
Q

what is PKR? how does VA RNA affect it?

A

detects virus infection by binding the dsRNA
- Phosphorylates itself then phosphorylates eIF2a to inhibit translation

VA RNA blocks this –> translation can continue

29
Q

why does PKR recognize a viral infection?

A

dsRNA is only present in a cell when a virus has infected it

30
Q

what is the role of E3?

A

immunosuppression to make infected cell bypass immune system

31
Q

can we see E3 function in cell culture?

A

no, it only works in an in vivo system where the immune system is present

32
Q

what are 3 functions of E3?

A
  1. internalize TNF/fas receptors so cell can’t recognize virus
  2. inhibit MHC complex so cell can’t present peptides
  3. makes Adenovirus Death Protein so virus can easily be released from cell

MIMM 324 (37 decks)

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