Bacterial Evasion

Question 1

Gram positive bacteria

Answer 1

•staphylococcus epidermidis
•staphylococcus aureus
•streptococcus pyogenes

Question 2

Gram negative enterobacteriaceae

Answer 2

•escherichia Coli
•salmonella enterica
•yersinia pestis

Question 3

What pathogen type is S. epidermidis

Answer 3

Extra cellular

Question 4

What type of pathogen is S. Aureus

Answer 4

extracellular

Question 5

What pathogen type is S. pyogenes

Answer 5

Extra cellular

Question 6

What infections does S. epidermidis cause

Answer 6

•medical device infections

Question 7

What infections does S. aureus cause

Answer 7

•skin infections
•pneumonia

Question 8

What infections does S. Pyogenes cause

Answer 8

•throat infections

Question 9

What type of pathogen is E. coli

Answer 9

•extra cellular

Question 10

What type of pathogen is salmonella enterica

Answer 10

Intracellular

Question 11

What type of pathogen is yersinia pestis

Answer 11

Intracellular

Question 12

What infections does E. coli cause

Answer 12

Diarrhoea

Question 13

What infections does salmonella enterica cause

Answer 13

Diarrhoea

Question 14

What infections does does yersinia pestis cause

Answer 14

•fever
•systemic infections
•pneumonia

Question 16

Major cytokines helper T cells produce

Answer 16

•IFN-gamma
•IL-10 + TGF-beta
•IL-4, 5, 13
•IL-17

Question 17

What does IFN-gamma do

Answer 17

•protects against = intracellular pathogens
•induces = autoimmunity

Question 18

What does IL-10 and TGF-beta do

Answer 18

•protects against = autoimmunity allergies
•induces = chronic infections

Question 19

What does IL-4, 5, 13 do

Answer 19

•protects against = helminths
•induces = allergy + autoimmunity

Question 20

What does IL-17 do

Answer 20

•protects against = bacteria + fungi
•induces = autoimmunity

Question 21

2 main mechanisms of immune evasion

Answer 21

•hide
•produce effector proteins

Question 22

How do pathogens hide

Answer 22

•protective coat
•changing their coat

Question 23

What evasion effectors do pathogens produce

Answer 23

•toxins/poisons
•resist destruction
•mimic/inhibit host proteins

Question 24

Staphylococcus Aureus + streptococcus modes of evasion

Answer 24

•interfering with complement
•interfering with ROS chemistry
•control the cell wall

Question 25

Interfering with complement mechanism

Answer 25

1. Prevent C3 convertase formation 2. Degrade C3b 3. Prevent C5 convertase 4. Degrade C5a 5. Resists MAC lysis

Question 26

What is the mechanism for interfering with ROS chemistry

Answer 26

•prevent formation of most toxic molecules (for the bacteria not humans) •hypochlorite ion mainly

Question 27

What is the function of bacteria pigment

Answer 27

*antioxidant shield against superoxide

Question 28

What is superoxide dismutase

Answer 28

•enzyme that protects from ROS damage •from pigment

Question 29

Superoxide dismutase mechanism for protection

Answer 29

•diverts the pathway of reaction •stops damaging species to be made •protects against superoxide

Question 30

How do S. auereus and Streptococcus alter their cell wall

Answer 30

•degrades AMP (stops AMP binding molecules) •changes in wall density prevent access •modulation of PPG prevents lysozyme

Question 31

S. epidermidis description

Answer 31

•gram +ve •natural flora of skin

Question 32

S. Epidermidis virulence mechanisms

Answer 32

•bio film formation 3 mechanisms: 1.polysaccharide intercellular adhesion (PIA) 2.accumulation associated protein (AAP) 3.extra cellular matrix binding protein (Embp)

Question 33

What do polysaccharide intercellular adhesion (PIA) biofilms do

Answer 33

*avoids host defence peptides *avoids neutrophil activity * inhibits opsonisation (marked for host) *increases inflammation (via IL-8)

Question 34

Enterobacteriaceae mode of evasion

Answer 34

•interfering with TIR domain proteins

Question 35

What is the TIR domain

Answer 35

•toll/interleukin 1 receptor (TIR) domains are intracellular parts of toll like receptors (TLRs)

Question 36

4 groups of phagocytic receptors

Answer 36

•complement •Fc gamma •lectin •scavenger

Question 37

Cis phagocytosis receptors

Answer 37

•lectin •scavenger

Question 38

Cis phagocytosis meaning

Answer 38

Direct

Question 39

Trans phagocytosis receptors

Answer 39

*complement *Fc Gamma

Question 40

Trans phagocytosis meaning

Answer 40

•indirect - opsonins

Question 41

How does E Coli interfere with phagocytosis

Answer 41

•EspB+F = inhibit scavenger •EspJ = inhibit complement and Fc Gamma •EspH = inhibits actin

Question 42

What do EspB+F do

Answer 42

•inhibit phagocytosis via scavenger

Question 43

What does EspJ do

Answer 43

•inhibits phagocytosis via complement and Fc Gamma

Question 44

What does EspH do

Answer 44

Inhibits actin polymerisation

Question 45

What is serum resistance bacteria

Answer 45

Bacteria that can survive in the blood and resist effect of serum

Question 46

Mechanisms of E. coli serum resistance

Answer 46

*prevent opsonisation (colonic coat) *OmpA - prevents complement *OmpC - decreases complement expression *TraT - inhibit MAC formation *MLiC - degrades lysozyme

Question 47

What is MAC and its functions

Answer 47

Complement Membrane Attack Complex •causes osmolysis

Question 48

How does salmonella respond quickly and reversibly to the environment

Answer 48

Using phase variation

Question 49

Example of phase variation by salmonella

Answer 49

•salmonella access M cells •dendrites sample cell and find a salmonella expressing FliC (flagellin) •T cells told to look for cells with FliC •salmonella stops expressing FliC reversibly

Question 50

Yersinia evasion mechanism

Answer 50

•expression of Yersinia outer protein P (Yop P) •inhibit inflammatory cytokine release

Question 51

Top 3 effects of Yop P

Answer 51

1. Inhibits phagocytosis 2. Stops MHC 1 presenting to CD8 3. inhibits actin cytoskeleton

Question 52

What does OmpA do

Answer 52

*E. Coli *binds c4bp + prevents complement activation

Question 53

What does OmpC do

Answer 53

*E. Coli *induces complement but expression can be decreased

Question 54

What do TraT and Iss do

Answer 54

*E. Coli *inhibit stages of MAC formation

Question 55

What does MliC do

Answer 55

*E. Coli *Protease that degrades lysozyme