Host Immunity And Pathogen Evasion

Question 1

What 4 agents can be infectiois

Answer 1

Opportunists , pathogenic , commensals or transposable retrovirus elements

Question 2

What is virus tropism

Answer 2

Ability for viruses to infect a cell type successfully

Question 3

What is this dependant on

Answer 3

Host factors eg diabetes link to covid

Question 4

What 2 major things did diabetes do as a severe comorbidity of covid

Answer 4

Impair ifna production which is antiviral

Upregulste ace2 receptors

Question 5

What are the diff ways viruses can be cytopathic to cells

Answer 5

Hi Jack cells and stop protein synthesis

Cause cell death after utilising them

Can cause cell cell fusion forming giant synctium which eventually cause cell death and allows viral spread

Question 6

Do non cytopathic viruses exist

Answer 6

Yea eg lcmv but still cause cell stress

Question 7

Explain the cycle of tissue damage from both virus and inflammation

Answer 7

Infection

Detected by prr

Also cause cytopathicity = tissue damage

Pamps and damps now detected both

Cause inflammation which causes even more tissue damage eg via mmp, ros

Question 8

How does vessel leakage eventually occur and immune cell influx

Answer 8

Selectins , cams upreg

And vessel leakage via cytokines eg TNFa but also others like pg

Question 9

If defences are successful, what is the course of innate then adaptive

Answer 9

2 weeks inmate
Then adaptive with igm to start.
Long term protection from igG and iga

Question 10

Which chemokines which are triggered in innate by ifn type 1 and y allow adaptive immunity link

Answer 10

Cxcl9,10,11

Question 11

What do they attract

Answer 11

Cells with cxcr3 which are mainly T cells, memory t , NK cells and apc

Question 12

What sort of ifn responsive genes are upreg by ifn antiviral

Answer 12

Pkr - blocks translation

OAS 2’5’ - degrade mrna

Question 13

How do they also allow for viral infected cell - T cell interaction

Answer 13

MHC 1 and II upreg

Question 14

What sort of prr can stimulate type 1 ifn production

Answer 14

Rig 1 and mda5 recognising dsrna

Question 15

Why is it said type 1 might cause persistent infection even if they’re antiviral acutely

Answer 15

Induce il10 producing tregs

Question 16

What sort of things do cd8 cells have to promote death

Answer 16

Fas L binding to fas on infected cells

Granzymes

Perforin
Antiviral ifnY

Question 17

What does il2 do

Answer 17

Promote expansion of CD8 via growth signals

Question 18

How do NK cells recognise downregulated MHC

Answer 18

Kir inhibitory recetor

Question 19

Which isotype can be switched by th1 which is why it’s the most common

Answer 19

Igga2

Question 20

Which th17 cytokines promotes sustained cd8 in chronic infection

Answer 20

Il21

Question 21

Which cd4 cell needed for plasma cell maturation and memory b cell

Answer 21

Tfh

Question 22

What sorts of things are antibodies needed for

Answer 22

Adcc via fc receptors eg on NK cells

Binding complement c1q

Neutralisation

Question 23

Why would fast replication of small viruses cause immune evasion

Answer 23

Immunity not kicked in fast enough

Question 24

How can viruses evolve

Answer 24

Mutations eg to stop hla from presenting

Question 25

Give 2 examples of hikacking cytokines responses

Answer 25

Can inhibit ifn eg covid

Can produce homolog of il10 (ebv)

Question 26

Despite persistent ifn response being suppressive eg via il10 or ido. How does it still cause chronic inflam

Answer 26

Via TNFa etc cytokines

Question 27

How has cytomegalovirus dealt with the fact downregulated MHC can activate NK

Answer 27

They produce a decoy MHC which mimics MHC on surface so NK not activated

Question 28

What is clonal exhaustion

Answer 28

When excessive viral ag is presented to overstimulate tcr to cause peripheral deletion or anergy

Question 29

How can infection in thymus cause immune tolerance eg congenital rubella

Answer 29

It causes central deletion of virus specific T cells