Immunity to meningitis Flashcards
(22 cards)
What is the main focus of the lecture on meningitis?
Understanding how bacteria reach the subarachnoid space
What immune mechanisms protect against invasive infection with encapsulated bacteria?
Immune mechanisms at mucosal surfaces and in the blood
What is the role of the spleen in protecting against invasive infections?
It clears poorly and non-opsonised bacteria from the blood
What are the three mechanisms of complement activation?
- Lectin pathway (microbial glycans)
- Classical pathway (antibody)
- Alternative pathway (deposition of spontaneously formed C3b)
How does the alternative pathway of complement activation begin?
It is initiated by C3b
What are the roles of C5a and C3a in the immune response?
- Activates endothelium
- Increases vasodilation
- Increases vascular permeability
- Increases cell-adhesion molecules
What is the effect of capsules of S. pneumoniae, N. meningitidis, and H. influenzae on the immune response?
They mask complement and antibody, inhibiting opsonisation and phagocytosis
What is the significance of anti-capsular antibodies?
They are required for efficient opsonisation and phagocytosis
What is the consequence of splenectomy regarding infections?
Increased risk of overwhelming infections, especially with encapsulated bacteria
What types of vaccines are available for Neisseria meningitidis?
- Capsular polysaccharide vaccine (A, C, Y, W-135)
- Conjugate polysaccharide vaccine (MenACWY, MenC)
What is the difference between polysaccharide and conjugate vaccines?
- Polysaccharide:
- No T cell response
- No immune memory
- Conjugate:
- Yes to both T cell response and immune memory
Which vaccine is used for Streptococcus pneumoniae?
- Pneumococcal capsular polysaccharide vaccine (23 serotypes)
- Protein conjugate vaccines (7 to 13 common serotypes)
What is herd immunity in the context of vaccination?
It is the indirect protection from infectious disease that occurs when a large percentage of a population becomes immune
What is the immunization schedule for MenB in New Zealand?
All infants and a catchup program for those aged 13-59 months
What is the role of B lymphocytes in the immune response?
They make antibodies which are secreted across the epithelium
True or False: The classical pathway of complement activation uses the C1 complex.
True
Fill in the blank: The _______ pathway of complement activation is initiated by microbial glycans.
[Lectin]
What is the importance of the membrane attack complex (MAC) in immunity?
It destroys membrane integrity, leading to the killing of pathogens
What types of immune responses are triggered by PRRs (Pattern Recognition Receptors)?
Recruitment of neutrophils and activation of immune cells
What is the expected immune response for children under 2 years to polysaccharide vaccines?
No response
What is the role of the spleen in limiting invasive infections?
It is the main organ that clears poorly and non-opsonised bacteria from the blood
What is the key requirement for protection against Haemophilus influenzae Type B?
Anti-capsular antibodies
