Immunity To Virus Infections

Question 1

What two types of genomes can a virus possess?

Answer 1

RNA or DNA

Question 2

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

Answer 2

HIV

Question 3

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

Answer 3

Hepatitis A or rhinoviruses

Question 4

How does HIV cause chronic infection?

Answer 4

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

Question 5

What type of infection do HepB and C cause?

Answer 5

Acute or chronic

Question 6

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

Answer 6

Chronic have a more equilibrium state

Question 7

What are chronic infections characterised by?

Answer 7

Progressive replication, suppression of immune responses

Question 8

Can innate response have memory?

Answer 8

Potentially yes

Question 9

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

Answer 9

Viral proteins
Viral nucleic acid
Infected cells
Altered host proteins

Question 10

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

Answer 10

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

Question 11

What type of genome does HIV have?

Answer 11

RNA genome

Question 12

What are the components of a virion?

Answer 12

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

Question 13

What do matrix proteins do?

Answer 13

Cause shape of virus particle to adopt circle/spherical structure

Question 14

What shape is capsid in HIV?

Answer 14

Bullet shaped

Question 15

What do host proteins help the virus do?

Answer 15

Evade host immune responses

Question 16

What does the humoral response do in recognising viral proteins?

Answer 16

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

Question 17

What happens in the innate stage of recognising viral proteins?

Answer 17

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

Question 18

What happens with antibodies recognising viral proteins?

Answer 18

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

Question 19

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

Answer 19

In a lipid bilayer or enveloped virus

Question 20

What type of receptor are RNA viruses sensed by?

Answer 20

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

Question 21

What type of receptors are DNA viruses recognised by?

Answer 21

Cyclic di nucleotide receptors

Question 22

What are the 3 different signalling pathways after sensing viruses?

Answer 22

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

Question 23

What does TBK1 phosphorylate and what does this do?

Answer 23

IRF3 , this switches on interferon

Question 24

What are the major effector functions of ISGs?

Answer 24

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

Question 25

What does protein kinase R inhibit?

Answer 25

Translation of viral proteins

Question 26

Is interferon gamma anti-inflammatory or pro-inflammatory?

Answer 26

Pro-inflammatory

Question 27

What are the two groups of ISGs?

Answer 27

Classical ISGs New ISGs

Question 28

What is PKR induced by?

Answer 28

IFN

Question 29

What does PKR recognise?

Answer 29

DsRNA assocaited with virus replication

Question 30

What does PKR phosphorylate?

Answer 30

EIF2a, inhibiting protein expression

Question 31

What does PKR recruit?

Answer 31

Caspases, triggering apoptosis

Question 32

What does PKR do?

Answer 32

Activates NFkappaB, promoting inflammation

Question 33

What does tetherin act against?

Answer 33

Against enveloped virus

Question 34

How does tetherin act?

Answer 34

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

Question 35

What does tetherin prevent?

Answer 35

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

Question 36

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

Answer 36

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

Question 37

What can dendritic cells do?

Answer 37

Display fragments of soluble antigens on MHC1

Question 38

What are CD8+ cells activated by?

Answer 38

MHC1 expressed viral peptides

Question 39

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

Answer 39

Work with antibodies

Question 40

What are NK cell effectors?

Answer 40

Performing Granzymes A-defensins

Question 41

What is ALT a marker of?

Answer 41

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

Question 42

What happens in HAV infection?

Answer 42

Infects liver, doesn’t usually establish a prolonged infection

Question 43

What happens early on in HAV infection?

Answer 43

Get large amounts of viral RNA, then liver damage

Question 44

What happens once you have HAV specific T cell response?

Answer 44

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

Question 45

Why is ISG response lower in hepB than hepA?

Answer 45

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

Question 46

What is assocaited with reduction of virus in hep B?

Answer 46

T cell response

Question 47

What is stronger in HepC than HepB?

Answer 47

Much stronger interferon stimulated gene expression

Question 48

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

Answer 48

30% of cases

Question 49

What are viral mechanisms for evading host immunity?

Answer 49

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

Question 50

What do vaccinia and pox viruses block?

Answer 50

Phosphorylation of eIF2a

Question 51

What viruses inhibit tetherin?

Answer 51

HIV1/2, dengue and Ebola

Question 52

What does HIV express that triggers degradation of tetherin?

Answer 52

Vpu

Question 53

What do TLRs recognise?

Answer 53

Double stranded RNA

Question 54

What has no error checking?

Answer 54

RNA-dependent RNA polymerase

Question 55

What is a mutation rate?

Answer 55

Rate of error produced by a viral polymerase

Question 56

What is substitution rate?

Answer 56

Rate at which polymorphisms become fixed in a population

Question 57

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

Answer 57

RNA viruses