Viral response to host response (#4)

Question 1

How to avoid IFN outiside

Answer 1

Viruses encode proteins to prevent IFN binding : called viral IFN-αβR and viral IFNγR on the cell surface of infected cells

Question 2

Proteins to avoid IFN: called viral _____and viral _____ on the cell surface of infected cells

Answer 2

IFN-αβR

IFNγR

Question 3

viral evasion of IFN signaling from within
referring to PKR
2 mech

Answer 3

1. encodes its own structured RNA and binds to PKR to inhibit its acivation by dsRNA
2. proteins that sequester dsRNA and prevent PKR activation

Question 4

Viral evasion of elF2 mechanism

2 mech

Answer 4

1. viral proteins that directs cellular phsphatase to dephosphoryate ElF-2α or
2. ELF=2α decoys that bind to activated PKR and prevent it from acting on ELF-2α

Question 5

Viral evasion of IFN

Answer 5

Decoy receptors that baind to IFN and seqester it before it binds to cellular R

Question 6

How can a virus stop fever activity

Answer 6

viral IL-1β bind proteins will seqester IL-1β and ≠ it’s pyrogenic activity

Question 7

Complement is highly regulated cascade with “control” proteins on their surface to block complement activation. Bacterial surfaces and some enveloped viral surfaces lack these complement control proteins so complement can

Answer 7

activate antiB-Independent virolysis

so this is how they are destroyed by complement

Question 8

How can a virus avoid complement

Answer 8

Viruses will encode homologs of complement control proteins that prevent assembly of the MAC complex
Can encapsidate viral or host complement control proteins in their membranes to evade complement-mediated lysis

Question 9

Viruses will encode homologs of complement control proteins that prevent assembly of the :

Answer 9

MAC complex

Question 10

Complement avoidance: Can _____viral or host complement control proteins in their membranes to evade complement-mediated lysis

Answer 10

encapsidate

Question 11

How does virus overcome MHC I expression

Answer 11

remove MHC I from surface of infected cells, removing some HLA-A and –B and leaves HLA-C alone

Question 12

What affect can a virus have on the NK cell receptor ligand?

Answer 12

retaining them in the ER or rerouting them to lysosomes so they can’t get to surface.

Question 13

How does virus inhibit NK and MHCI interaction

Answer 13

Encodes decoy MHC I like molecules that interact with inhibitor NK receptors so NK’s don’t target them

Question 14

viruses will downregulate:

Answer 14

ICAMS

B7 (co-stimulatory molecule)

Question 15

What does a virus make to avoid apoptosis

Answer 15

vTNF-Rs that bind to TNF’s that IG would bind to the TNF receptor on cell surface to signal apoptosis

Question 16

Ways to downregulate MHC I

Answer 16

1. Degrades TAP transporter
   . Block peptide transporter into ER by blocking TAP transporter
   Degrade class I MHC
   Retain class I MHC molecules in ER/golgi
   Divert class I MHC to lysosomes—then they get degraded
   Downregulate transcription of components of MHC molecule

Question 17

How helps can virus inhibit apotosis from witin

Answer 17

viral inhibitors of capsases that block proteolytic steps of capsase activation and target protein cleavage

Question 18

virus can encodes homologue for anti-apoptotic proteins like:

Answer 18

Bcl-2

Question 19

Virus encoded inhibitors of _____which is a major inducer of apoptosis from within

Answer 19

p53