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Viral Pathogenesis And Infection > Immunity To Virus Infections > Flashcards

Immunity To Virus Infections Flashcards

1
Q

What two types of genomes can a virus possess?

A

RNA or DNA

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2
Q

What is an example of a virus that always causes a chronic infection?

A

HIV

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3
Q

What is an example of a virus that only causes acute infection?

A

Hepatitis A or rhinoviruses

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4
Q

How does HIV cause chronic infection?

A

It integrates its genome into T cell chromosomes and macrophage chromosomes and persists for a long period of time

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5
Q

What type of infection do HepB and C cause?

A

Acute or chronic

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6
Q

Does acute or chronic viral infections have a more equilibrium state?

A

Chronic have a more equilibrium state

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7
Q

What are chronic infections characterised by?

A

Progressive replication, suppression of immune responses

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8
Q

Can innate response have memory?

A

Potentially yes

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9
Q

What are examples of virus-associated molecules recognised by the immune system?

A

Viral proteins
Viral nucleic acid
Infected cells
Altered host proteins

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10
Q

What happens if host proteins do some work and cause conformational changes to help the virus?

A

If the host protein is created in a different way, it creates a neo antigen so despite it being self, it can be recognised by the immune system

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11
Q

What type of genome does HIV have?

A

RNA genome

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12
Q

What are the components of a virion?

A

Nucleic acid
Matrix proteins
Capsid
Enveloped virus
Spike proteins
Host molecules embedded in membrane e.g. HLA class 1

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13
Q

What do matrix proteins do?

A

Cause shape of virus particle to adopt circle/spherical structure

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14
Q

What shape is capsid in HIV?

A

Bullet shaped

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15
Q

What do host proteins help the virus do?

A

Evade host immune responses

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16
Q

What does the humoral response do in recognising viral proteins?

A

Recognise viral proteins through a bunch of sensors
This occurs before a cell is infected with virus

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17
Q

What happens in the innate stage of recognising viral proteins?

A

We have lectins that can stick to the carbohydrates and can bind to particle and neutralise them or they can recruit and activate complement cascade

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18
Q

What happens with antibodies recognising viral proteins?

A

Antibodies start out as b cell receptor, once b cell is activated, goes through class subtype switching and then soluble antibodies can neutralise
Antibodies also activate complement cascade in a similar way to the way lectins work

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19
Q

What can complement activation punch a hole in that is virus related?

A

In a lipid bilayer or enveloped virus

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20
Q

What type of receptor are RNA viruses sensed by?

A

RIG-like receptors
Bind to different types of viral RNA and trigger a signalling cascade

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21
Q

What type of receptors are DNA viruses recognised by?

A

Cyclic di nucleotide receptors

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22
Q

What are the 3 different signalling pathways after sensing viruses?

A

TLRs - TRIF
RLRs - MAVS
And for foreign DNA - sting pathway

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23
Q

What does TBK1 phosphorylate and what does this do?

A

IRF3 , this switches on interferon

24
Q

What are the major effector functions of ISGs?

A

Reduction in transcription of viral RNA
Reduction of virus protein expression
Degradation of dsRNA
Editing of viral RNA
Modification of viral proteins

25
Q

What does protein kinase R inhibit?

A

Translation of viral proteins

26
Q

Is interferon gamma anti-inflammatory or pro-inflammatory?

A

Pro-inflammatory

27
Q

What are the two groups of ISGs?

A

Classical ISGs
New ISGs

28
Q

What is PKR induced by?

A

IFN

29
Q

What does PKR recognise?

A

DsRNA assocaited with virus replication

30
Q

What does PKR phosphorylate?

A

EIF2a, inhibiting protein expression

31
Q

What does PKR recruit?

A

Caspases, triggering apoptosis

32
Q

What does PKR do?

A

Activates NFkappaB, promoting inflammation

33
Q

What does tetherin act against?

A

Against enveloped virus

34
Q

How does tetherin act?

A

Binds to the surface of glycoproteins
Act against a wide range of viruses

35
Q

What does tetherin prevent?

A

Release of the virus while budding
Retained particles are targeted for degradation

36
Q

What cytokines do CD4 T cells produce that can switch on cytotoxic T cells?

A

IL-2, IL-12, interferon gamma and TNF alpha

37
Q

What can dendritic cells do?

A

Display fragments of soluble antigens on MHC1

38
Q

What are CD8+ cells activated by?

A

MHC1 expressed viral peptides

39
Q

What do NK cells work with to eliminate virus infected cells?

A

Work with antibodies

40
Q

What are NK cell effectors?

A

Performing
Granzymes
A-defensins

41
Q

What is ALT a marker of?

A

A marker of liver damage - released into bloodstream means liver damage

42
Q

What happens in HAV infection?

A

Infects liver, doesn’t usually establish a prolonged infection

43
Q

What happens early on in HAV infection?

A

Get large amounts of viral RNA, then liver damage

44
Q

What happens once you have HAV specific T cell response?

A

Get reduction in RNA, T cell response is critical part to clear virus infection

45
Q

Why is ISG response lower in hepB than hepA?

A

Interferon is not switched on by HepB, has a whole way of knocking out interferon

46
Q

What is assocaited with reduction of virus in hep B?

A

T cell response

47
Q

What is stronger in HepC than HepB?

A

Much stronger interferon stimulated gene expression

48
Q

In what percent of cases does self limiting acute HCV occur in?

A

30% of cases

49
Q

What are viral mechanisms for evading host immunity?

A

Replication in privileged sites
Protease cleavage of host innate immunity proteins
Blocking ISGs
Down-regulation of immune mediators
Rapid mutation

50
Q

What do vaccinia and pox viruses block?

A

Phosphorylation of eIF2a

51
Q

What viruses inhibit tetherin?

A

HIV1/2, dengue and Ebola

52
Q

What does HIV express that triggers degradation of tetherin?

A

Vpu

53
Q

What do TLRs recognise?

A

Double stranded RNA

54
Q

What has no error checking?

A

RNA-dependent RNA polymerase

55
Q

What is a mutation rate?

A

Rate of error produced by a viral polymerase

56
Q

What is substitution rate?

A

Rate at which polymorphisms become fixed in a population

57
Q

What has a higher mutation rate, DNA or RNA viruses?

A

RNA viruses

Viral Pathogenesis And Infection (16 decks)

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