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Antiviral Immunity > Viral Evasion > Flashcards

Viral Evasion Flashcards

1
Q

5 viruses that evade RNA detection?

A 
Influenza - NS1
Lassa - nucleoprotein 
HepB - X protein
HCV - NS5A
HIV - cellular inhibitor
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2
Q

How does influenza evade RNA detection?

A

Binds vRNA

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3
Q

How does Lassa virus evade detection?

A

Nucleoprotein digests free dsRNA

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4
Q

What does HepB X protein do?

A

Degrades MAVs to evade RNA induced responses from RIGI-I

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5
Q

How does HIV evade RNA signalling inducing immune responses?

A

Induces expression of cellular RNaseL inhibitor

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6
Q

How does 2,5 oligoadenylate synthetase induce antiviral responses?

A

Activates RNaseL dimerisation in response to RNA detection

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7
Q

How does HCV act in 2,5OAS?

A

NS5A binds so it can’t activate RNaseL

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8
Q

3 viruses that evade DNA induced responses?

A

HIV-1
Dengue
HCMV

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9
Q

How does HIV degrade excess DNA?

A

Hijacking cellular 3-5 exonuclease

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10
Q

How does dengue virus evade DNA responses?

A

NS2B-3 protease degrades STING so no cGAS/IFI16 responses

And no signalling to neighbouring cells

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11
Q

How does HCMV evade DNA detection?

A

Targets IFI16 to either mislocalise to ER (not nucleus) or prevent oligomerisatiom

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12
Q

How does HCV evade TLR?

A

NS5A binds TLR7/9 MyD88

NS3/4A protease cleaves TLR3 TRIF

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13
Q

How can viruses prevent responses to IFN?

A

Polio activates PKR degradation

Vaccinia K3L pseudosubstrate blocks PKR autophos

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14
Q

How can viruses evade detection?

A

DNA
RNA
TLR signalling
Preventing signalling in response to IFN

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15
Q

How can HCMV evade activation of adaptive immunity?

A

miRNA inhibits ERAP protease transcription
US6 inhibits TAP ATP binding
US2 & 11 target MHC1 to ERAD

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16
Q

How can adenovirus strain 12 evade immune responses?

A

E1A inhibits TAP and MHC1 transcription as NFKB isn’t phosphorylated by PKA

17
Q

Does Adenovirus strain 12 have E3/19K?

A

No

18
Q

How does KSHV evade MHC activation?

A

K3 and K5 ubiquitinate surface MHC1 for endocytosis and degradation

19
Q

How does EBV evade MHC presentation?

A

Resistant to proteolysis so no peptides to present during latency

20
Q

How does HSV evade antigen presentation?

A

ICP47 inhibits peptide binding by TAP

21
Q

How can antigenic variation reduce antiviral responses?

A

Mutations,
Recombination
Reassortment of segmented genomes

22
Q

Why does antigenic variation reduce CTL activation?

A

No consistent recognition of peptides for clonal expansion

23
Q

How does HIV induce antigenic variation?

A

Low fidelity replication introduces mutations

24
Q

Which virus can evade “loss of MHC” responses?

A

HCMV

25
Q

4 proteins that HCMV uses to evade NK killing due to loss of MHC?

A

UL18 homolog of MHC
UL40 has TAP independent presentation to maintain HLA-E
UL16 blocks expression of ligands induced by stress of viral infection
miR-UL112 blocks MICB translation

Antiviral Immunity (2 decks)

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