Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

POM > immune evasion > Flashcards

immune evasion Flashcards

1
Q
  • What 2 groups can the diseases caused by S. aureus* be divided into?
A

Localised pyogenic (pus-producing) diseases characterised by tissue destruction meditated by hydrolytic enzymes and cytotoxins

Diseases mediated by toxins that function as superantigens producing systemic diseases.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q
  • What is antibody opsonisation?
A

Antibodies bind bacterial antigens allowing:

Deposition of complement in classical complement pathway

Neutrophils and other phagocytes to have the ability to detect invading microbes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q
  • What are 5 of the general strategies against antibody opsonisation that S. aureus carries out?
A

Hide antigens

Disrupt functions

Prevent detection

Degrade antibodies

Modify antigenicity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q
  • How does S aureus hide its antigens?
A

expression of S. aureus capsule

Helps to hide antigenic structures that can be detected by innate and adaptive immune components

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q
  • How does S. aureus disrupt the function of antibodies to evade opsonisation?
A

S. aureus expresses protein A (SpA)

SpA surface protein binds microbe receptors via their Fc region

SpA prevents normal opsonisation as antibodies cannot bind to microbes, and therefore neutrophils cannot detect S. aureus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q
  • How does S. aureus prevent detection by neutrophils to aid evasion of antibody opsonisation?
A

SSL10 is a secreted protein that binds to Fc region of IgG

SSL10 prevents Fc receptors on neutrophils from detecting IgG on the surface of *S. aureus*
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q
  • What is complement opsonisation?
A

Complement system is comprised of a large number of proteins that react with one-another to opsonise pathogens (attract phagocytosis) or to directly kill them by membrane attack complex (Mac) formation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q
  • What are the 4 general strategies that bacteria use to prevent C3b or MAC deposition?
A

Inhibit C3/C5 convertases (prevent C3b, C3a and C5a formation)

Bind complement factors and prevent their processing (bind to C3- C3b can't be formed)

Cleave complement factors

Acquire host-derived complement regulators - C3b is inactivated by fH on bacterial surface
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q
  • How does SCIN allow evasion by S. aureus of complement opsonisation?
A

S. aureus SCIN protein binds C3bBb

Preventing:

C3b deposition

C3a formation

C5a formation

Formation of Membrane Attack Complex
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q
  • How does SCIN allow evasion by S. aureus of complement opsonisation?
A

S. aureus SCIN protein binds C3bBb

Preventing:

C3b deposition

C3a formation

C5a formation

Formation of Membrane Attack Complex
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q
  • How does Efb allow evasion by S. aureus of complement opsonisation?
A

S. aureus Efb protein binds C3d in C3b, which induces conformation change

Preventing:

Binding of factor B to C3b- no C3 convertase so no C5 convertase so complement cascade shuts down

C3dg binding CR2-lowers phagocyte detection
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q
  • How does SSL7 prevent complement opsonisation?
A

Inhibits MAC formation by binding to C5, preventing break down into C5a & C5b

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q
  • What is the function of the immune receptors on neutrophils?
A

Allow neutrophils to sense and respond to their environment

Detect microbes, microbial products or self-proteins
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q
  • What are Pathogen Recognition Receptors?
A

Directly detect microbes or microbial products

Neutrophils are primed or activated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q
  • What are three examples of PRRs and what do they detect?
A

TLR receptors - Conserved microbial structures

CLEC receptors - Microbial Carbohydrates

FPR receptors - Formylated peptides
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q
  • What do Fc receptors often signal through activating?
A

activating Motifs called ITAMS in their cytoplasmic tails

17
Q
  • What do activatory receptors do?

- Give 2 of the types of activatory receptors

A

Enhance cell immune response

Cytokine receptors

Chemoattractant receptors
18
Q
  • Give 2 of the types of inhibitory receptors
A

LAIR receptors

SIGLEC receptors
19
Q
  • What are the 5 general strategies of S. aureus that dysregulate neutrophil functions?
A

Inhibit chemotaxis

Inhibit detection of bacteria

Kill neutrophils

Stimulate inhibitory receptors

Disrupt intracellular signalling
20
Q
  • How does S. aureus CHIPs inhibit chemotaxis?
A

CHIPs binds to C5aR and FPR1 and prevents binding of their agonists (C5a & formylated peptides)

Neutrophil do not migrate at sites of infection and do not become activated by C5aR and FPR1
21
Q
  • How does S. aureus FLIPr & SSL5 prevent Fc receptor mediated phagocytosis?
A

FLIPr binds to Fc-gamma receptors preventing detection of IgG-opsonised bacteria

SSL5 inhibits Fc alpha receptors, preventing detection of IgA

Reduces antibody mediated phagocytosis and killing of S. aureus
22
Q
  • How can S. aureus kill and inhibit neutrophils?
A

They can kill neutrophils with toxins

They can express molecules that are receptors on neutrophils antagonists
23
Q
  • What is the function of Factor H?

- The Membrane Attack Complex (MAC) is formed of which components?

A

Inhibits C3 convertases

C5b, C6, C7, C8, C9

POM (47 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions