Breakout 6

Question 1

evasion strategies that change how you look

Answer 1

genetic rearrangement
point mutations
genomic shuffling

Question 2

evasion strategies to block immune system

Answer 2

decoys
competitive inhibitors
non-functional homologs

Question 3

evasion strategies to change the microenvironment

Answer 3

promote a non-productive immune response

Question 4

evasion strategies to hide from immune system

Answer 4

infect immunopriveleged sites
latency
blocking antigen presentation

Question 5

genetic arrangement to avoid immune system
-example

Answer 5

african trypanosomes
* protozoan parasite that cause african sleeping sickness
* only 1 glycoprotein expressed at time
* can change glycoprotein expressed to evade immune response
* antibodies dont recognize it bc it can change glycoprotein

Question 6

point mutations lead to antigenic diversity

Answer 6

error prone viral and bacterial polymerases can lead to inherited mutations -> change “looks”

Question 7

genome shuffling
example

Answer 7

influenza has 9 RNA segments all be encapsidated into one virus

Question 8

antigenic shift in influenza

Answer 8

MAJOR and drastic
due to reassortment event involve gene segments coding for hemagluttinin glycoprotein
- immune respone absent

Question 9

antigen drift in influenza

Answer 9

slow change and not drastic
point mutation
immune response may be decreased due to change in affinity for antigen or protective Abs may not work anymore

Question 10

the evasion strategies that block the immune system all attack the

Answer 10

complement pathway

Question 11

mechanism 1 of block immune system:
recruit and/or production of negative regulators

Answer 11

production of DAF homolog
dissociates C3 convertase of classical pathwy

Question 12

mechanism 2 of block immune system:
inactivate complement cascade with enzymes

Answer 12

production of enzymes that degrade C3 into C3a-like and C3b-like
prevents activation of both classical and alternative pathway

Question 13

mechanism 3 of block immune system:
direct inhib with comp binding/direct interaction

Answer 13

production of Fc receptor which binds antibodies
prevent activation of both classical and alternative

Question 14

cont. direct inhibition with competitive binding/direct interaction

Answer 14

bacteria make own Fc receptor so they cant be phagocytosed and tagged for destruction

Question 15

additional examples of direct inhibition w/competitive binding/direct interaction

Answer 15

production of CD59 homolog that prevents formation of membrane attack complex

Question 16

change the microenvironment:
cytokines environment is very important for promoting

Answer 16

appropriate immune responses

Question 17

change the microenvironment:
pathogens have generated…

Answer 17

cytokines homologs
cytokine receptor homologs

Question 18

1 mechanism of change the microenvironment:
cytokine homologs

Answer 18

shift toward anti-inflammatory response
-ex: epstein barr virus produces homolog of IL-10

Question 19

IL-10 helps with

Answer 19

B cell proliferation and it is a anti-inflammatory cytokines

Question 20

IL-10 and its viral homolog

Answer 20

inhibits CD8+ T cell activity
promtoes B cell survival
epstein-barr virus replicates in B cells

Question 21

2 mechanism of change microenvironment:
cytokine receptor homologs

Answer 21

shift toward anti-inflammatory reponse
- vaccinia virus encodes soluble IFN-gamma receptor

Question 22

IFN-gamma mediated macrophage activation

Answer 22

unlike neutrophils, macrophages need to be activated for optimal functioning
fxns:
enhanced phagocytosis
antigen presentation
proinflammatory cytokines

Question 23

1 mechanism of hide from immune:
infect immunoprivileged sites

Answer 23

sites where lymphocytes do not circulate, so organisms can live undetected
ex: brain, eyes, spinal cord, pregnant uterus, testicles

Question 24

2 mechanism of hide from immune:
latency

Answer 24

no viral proteins made so virus is hidden from immune system
ex: herpes

Question 25

herpes simplex virus-1 establishes latency in neurons that express very low levels of

Answer 25

HLA class I so they stay hidden from CD8 T cells

Question 26

critical for humoral responses and helping CD8 cytolytic T cells

Answer 26

CD4 T cells

Question 27

critical for killing cells that harbor intracellular pathogens

Answer 27

CD8 T cells

Question 28

3 mechanism of hide from immune:
decrease expression of receptors involved in detection

Answer 28

pathogens hide from T cells by influencing HLA-I and HLA-II Ag presentation

Question 29

examples of decreasing expression of HLA class I

Answer 29

blocking proteosome degradation
preventing binding of peptides to TAP1/2
targeting HLA class I for internalization and degradation
ALL suppress CD8 T cell responses

Question 30

blocking proteosome degradation

Answer 30

prevents viral proteins from being processed into peptides and presented in HLA class I

Question 31

preventing binding of peptides to TAP1/2

Answer 31

prevents transportation into ER for loading into HLA 1/MHC class 1 molecules

Question 32

targeting HLA class I for internalization and degradation

Answer 32

removing HLA class I expression prevents CD8 T cell response just as other mechanisms do

Question 33

inhibit HLA class II from interacting with T cell receptor

suppress CD4 T cell responses

Answer 33

EBV virus gp42 sterically inhibits HLA class II
* reduced T helper cell recognition