Streptococcus Pneumoniae Prevention And Vaccination

Question 0

Immune complexes involved in killing of S pneumoniae

Answer 0

MAC1
FcgammaR
NADPH oxidase complex
Neutrophil extracellular traps

Question 1

MAC1

Answer 1

C3b receptor on macrophages

Initiates phagocytosis

Question 2

FcgammaR

Answer 2

On macrophages

For IgG-opsonised bacteria

Question 3

NADPH oxidase complex

Answer 3

Generates reactive oxygen and nitrogen radicals

Question 4

Neutrophil extra cellular traps

Answer 4

Nets extruded by neutrophils

DNA, cathelicidins

Question 5

Location of asymptomatic S pneumoniae replication

Answer 5

Nasopharynx

Question 6

Removal of C3b opsonised bacteria

Answer 6

Red blood cells express C3bR
Bind C3b opsonised bacteria
Splenic macrophages remove aged red blood cells, with bound antigen-C3b complexes

Question 7

T cell independent antigen

Answer 7

Polysaccharide

Eg: bacterial capsule

Question 8

Cells that detect polysaccharide capsule

Answer 8

CD5+ B1 B cells

Question 9

Why is there little memory response to S pneumoniae?

Answer 9

Only B1 B cells detect capsular antigen (no T cell response)
B cell secretes IgM, limited isotype switching to IgG (no Th response)
No memory

Question 10

Effective S pneumoniae vaccine design

Answer 10

Need conjugation, so that B cells make antibodies against polysaccharides, T cell receptors against protein epitopes

Results in isotype switching

Question 11

Issues with conjugates vaccines

Answer 11

Expensive

Around 50 tests on vaccine required before ready

Question 13

Serotype replacement

Answer 13

Non-vaccine serotype replaces serotype vaccinated against

Question 14

Features of the ideal prophylactic S pneumoniae vaccine

Answer 14

IgG secretion in blood, meninges

IgA secretion on mucosal surfaces

Question 15

Features of the ideal therapeutic S pneumoniae vaccine

Answer 15

Effective phagocytosis in spleen, tissues

Production of antibodies against capsular antigens

Question 16

First pneumococcal vaccine

Answer 16

1911

Whole cell killed vaccine

Question 17

Second pneumococcal vaccine

Answer 17

1983
Pneumococcal polysaccharide vaccine
Polysaccharide from 23 most common serotypes
– Protects against >80% of pneumococcal disease worldwide

Question 18

Efficacy of polysaccharide pneumococcal vaccine

Answer 18

Limited
Short-lived protection, as no memory response stimulated
~80% reduction in disease among immunocompetent adults

Question 19

Reason for lack of memory response from polysaccharide vaccine

Answer 19

No Th cell induction for isotype switching

Question 20

How do Th cells help B cells in antibody production?
1)
2)

Answer 20

1) Costimulation - CD40, CD40L

2) Providing a cytokine environment to stimulate isotype switching

Question 21

Th cell activation

Answer 21

APC presents antigen on MHC class II
CD80, CD86 (APC) interacts with CD28 (Th cell)
APC secretes cytokines

Question 22

T cell dependent antigen response
1)
2)
3)
4)
5)
6)

Answer 22

1) Protein antigens
2) No repeating epitopes
3) Response in infants
4) Isotype switching
5) High affinity antibodies produced
6) Memory cells produced

Question 23

T cell independent antigen response
1)
2)
3)
4)
5)
6)

Answer 23

1) Polysaccharide antigens
2) Repeating epitopes
3) No response in infants
4) No/limited isotype switching
5) Low affinity antibodies
6) No memory cells

Question 24

How to generate a T-cell response from a polysaccharide vaccine

Answer 24

Conjugate a protein epitope onto the relevant polysaccharide

Question 25

How do conjugated vaccines work?

Answer 25

Polysaccharide and connected protein are phagocytosed by B cell B cell presents protein epitope on MHCII T cells recognise protein epitope on MHCII, generate response

Question 26

A major viral cause of childhood meningitis

Answer 26

Haemophilus influenzae, type B

Question 27

Type of vaccine produced against Haemophilus influenzae type B

Answer 27

Conjugated

Question 28

Contents of Haemophilus influenzae type B conjugated vaccine 1) 2)

Answer 28

1) H. influenzae type B polysaccharide capsular antigen | 2) Tetanus toxoid protein or diptheria toxoid protein

Question 29

Polysaccharide making up H. influenzae type B capsule

Answer 29

Polyribosylribitol phosphate (PRP)

Question 30

How many different serotypes make up H. influenzae vaccine?

Answer 30

Seven - heptavalent

Question 31

Efficacy of conjugated S. pneumoniae vaccine

Answer 31

94% efficacy against vaccine serotypes

Question 32

Emerging pathogenic serotype of S. pneumoniae among vaccinated children

Answer 32

Serotype 19A

Question 33

PCV

Answer 33

Polysaccharide conjugated vaccine

Question 34

Most current PCV for streptococci

Answer 34

13v PCV | Contains serotype 19A