Week 6- Vaccination Flashcards
What is the aim of immunisation?
To provoke immunological memory to protect individuals against a disease if they encounter it in the future
What are some characteristics of an ideal vaccine?
Single dose Needle free Easy to administer Effective against all variants Gives life long protection Cheap Stable
Describe the general response to a foreign pathogen that leads to immunological memory
- Foreign antigen is encountered
- Innate cells are activated and turned to effector cells, they non specifically kill pathogen infected cells
- Antigens are released and taken up by APCs that display the antigen on their MHC
- T cells are activated and proliferate into a pool of effector cells that can clear the infection
- After response the pool is reduced to memory cells
What are the 3 main ways antibodies stop infection?
- Cover the pathogen to prevent it entering other cells
- Allow optophagocytosis as macrophages can recognize the antibody on the pathogen surface
- Boost the immune response
Where and how are B cell receptors (BCR) encoded?
They are encoded for by a single gene in the bone marrow before release. This gene is made by recombining multiple genes
What 3 fates do immature B cells have?
- Plasma cells- synthesized to become antibodies
- Memory cells- help protect against future infections
- Affinity maturation- B cells undergo point mutations in their BCR and are exposed to a small amount of antigen in the germinal centers of lymph nodes. Only the B cells that bind most effectively to the antigen are allowed to proliferate, increasing the effectiveness of B cells (this may be why multiple doses of vaccine are required: to encourage affinity maturation and increase protection)
What is a B cell receptor?
A surface bound antibody (with a heavy and light chain)
What is the R0?
Basic reproduction number, it displays how many people will be infected by someone who is already infected eg R0 of 3 means if I’m infected by a pathogen I’ll infect 3 other people by it who will each infect 3 other people by it etc
What do vaccines aim to do to the R0 in a population?
Bring it from above one to below one
How does herd immunity work?
It is a phenomenon that suggests not everyone has to be vaccinated. This is because if someone passes a pathogen onto someone who is immune, the chain of transmission is broken as it doesn’t matter whether the next person after that is immune or not
What are the 4 things found in a vaccine?
Antigen, adjuvant (increases immunity), stabilizers (eg buffer), water
What are the advantages/disadvantages and composition of an inactivated toxoid vaccine? Give an example of one
Composition: inactivated from of toxin secreted by the pathogen
Advantages: cheap, safe
Disadvantages: not all pathogens make toxins
Example: Tetanus
What are the advantages/disadvantages and composition of a recombinant protein vaccine? Give an example of one
Composition: recombinant form of protein secreted by virus
Advantages: pure, safe
Disadvantages: relatively expensive
Example: Hep B
What are the advantages/disadvantages and composition of a conjugate vaccine? Give an example of one
Composition: polysaccaride coat component paired with an immunological carrier
Advantages: very effective
Disadvantages: very strain specific, high cost
Example: pneumonia
What are the advantages/disadvantages and composition of a dead pathogen vaccine? Give an example of one
Composition: dead form of pathogen
Advantages: leaves antigen components in tact
Disadvantages: requires capacity to grow pathogen, killing it can alter the antigen, risk of contamination
Example: influenza split vaccine
