Microbiology 2: Viral evasion of host immunity

Question 1

Summarise the cellular immune response to viral infiltration of a cell

Answer 1

Viral proteins (endogenous) presented on surface by MHC1
CD8+ T cells recognise
Granzyme released –> cell death

Question 2

Which virus is the most significant example of a pathogen that undergoes considerable antigenic drift?

Answer 2

Influenza

Question 3

What is the gold standard for generating a vaccine?

Answer 3

To create exactly the correct antibody - a “sterilising immunity”

Question 4

What is the current most-promising avenue for production of a universal flu vaccine?

Answer 4

Produce a vaccine that targets the conserved “stalk” of the virus, rather than the “head” region that tolerates considerable amino acid variation

Question 5

What is Antigenic Shift?

Answer 5

Production of a totally new virus from antigenic change, eg a new subtyope from an animal source

Question 6

Name the most significant virus that demonstrates quasi-species existance

Answer 6

HIV

Question 7

How many antigenically-distinct serotypes of rhinovirus are there?

Answer 7

120

Question 8

How many antigenically-distinct serotypes of Poliovirus are there?

Answer 8

3

Question 9

What is TAP?

Answer 9

Protein involved in endogenous-antigen loading onto MHC1

Question 10

Recall 3 viral serotypes capable of evading antigen loading onto TAP

Answer 10

HSV ICP47
CMV US3
CMV US6

Question 11

Hos is TAP function evaded in HSV?

Answer 11

Blocks access of processed peptide to TAP

Question 12

Hos is TAP function evaded in CMV US3?

Answer 12

Inhibits tapasin (transfer molecule)

Question 13

Hos is TAP function evaded in CMV US6?

Answer 13

Prevents ATP binding to TAP

Question 14

How does KSHV evade immune system recognition?

Answer 14

Interferes with MHC presentation

Question 15

Give an example of a virus that can encode an MHC analogue and explain how this leads to evasion of immune response?

Answer 15

CMV

Fools NK cells into recognising MHC1 on their surface

Question 16

Recall the 3 ways in which HIV evades the immune system

Answer 16

1. Far-apart GP120 spikes
2. Glycan shield
3. Inaccessible CD4 binding site

Question 17

Describe the process of antibody-dependent enhancement in Dengue

Answer 17

Ig produced against one serotype upon initial infection will bind the new serotype but not neutralise it, leading to cytokine storm and haemorrhagic fever

Question 18

Recall the 2 methods by which Ebola evades the immune response

Answer 18

1. Antigen glycosylation

2. Soluble spike proteins “mop-up” Igs

Question 19

What are the 2 types of polio vaccine available?

Answer 19

SALK inactivated

SABINE live-attenuated

Question 20

What sort of cells are infected by measles?

Answer 20

CD120+ B cells - memory cells

Question 21

Why is the measles vaccine so important?

Answer 21

Measles infection –> impaired immunity and so many other infections afterwards