lecture 8 - immunity to meningitis

Question 1

What type of bacterial colonisation most commonly leads to meningitis?

Answer 1

Nasopharynx colonisation

Question 2

What type of cell in the epithelium takes up bacterial antigen during pneumococcal colonisation?

Answer 2

M cells

Question 3

How does the epithelium defend against invading colonising bacteria in the respiratory tract?

Answer 3

M cells take up antigen allowing antibodies to be made by B lymphocytes and secreted across the epithelium to protect again colonisation/invasive infection

Question 4

What are the 2 steps by which colonising bacteria enter the body to cause invasive disease?

Answer 4

Translocation across epithelium, bloodstream invasion

Question 5

What are the 3 mechanisms of complement activation?

Answer 5

Lectin pathway, Classical pathway, Alternative pathway

Question 6

What activates complement in the lectin pathway?

Answer 6

lectins/microbial glycans (carbohydrates) on the surface of pathogens

Question 7

What activates complement in the classical pathway?

Answer 7

The binding of antibodies to complement

Question 8

What activates complement in the alternative pathway?

Answer 8

The deposition of spontaneously formed C3b (complement protein 3b) on microbial surfaces

Question 9

What is the common product of all pathways of complement activation?

Answer 9

C3 convertase

Question 10

What is C3 convertase?

Answer 10

Protease that activates C3 complement proteins in the complement cascade

Question 11

How is the lectin pathway of the complement system activated?

Answer 11

Collectins made in the liver circulate in the blood and bind to microbial glycans which activates complement

Question 12

What is the key collectin the Lectin pathway of complement activation?

Answer 12

MBL (mannose binding lectin)

Question 13

What does C3 convertase cleave, and what are the products?

Answer 13

Cleaves C3 to C3a and C3b

Question 14

How does the complement system aid in phagocytosis?

Answer 14

C3b is deposited onto pathogens and is recognised by complement receptors on phagocytes

Question 15

How does the complement system causes pathogen cell lysis?

Answer 15

Cascade leads to the formation of the MAC (membrane attack complex)

Question 16

Which product of C3 cleavage is released?

Answer 16

C3a

Question 17

What are the effects of the release of C3a?

Answer 17

Local pro-inflammatory effects, and the recruitment of phagocytes

Question 18

How is C5 convertase formed?

Answer 18

C3b binds to C3 convertase

Question 19

What are the products of the cleavage of C5 by C5 convertase?

Answer 19

C5a (released), C5b (bound to pathogen surface)

Question 20

What is the role of C5b in the complement system?

Answer 20

Binds to pathogen surface to initiate MAC formation

Question 21

How does the MAC kill a pathogen?

Answer 21

Forms pore in cell membrane, loss of proton gradient, kills pathogen

Question 22

How are meningitis causing bacteria able to evade the complement and adaptive immune systems?

Answer 22

Their capsules mask complement and antibody inhibiting opsonisation and phagocytosis

Question 23

What organ is mostly responsible for the clearance of non-opsonised bacteria from the blood?

Answer 23

Spleen

Question 24

What organ is mostly responsible for the clearance of opsonised bacteria from the blood?

Answer 24

Liver

Question 25

What are the 2 key types of vaccines?

Answer 25

Polysaccharide vaccines, Conjugate vaccines

Question 26

Which class of vaccine produces no T cell response?

Answer 26

Polysaccharide vaccines

Question 27

Which class of vaccine produces a T cell response?

Answer 27

Conjugate vaccines

Question 28

What class of vaccine is avaiable for meningococcal B in NZ?

Answer 28

Polysaccharide