Immunology of Vaccination Flashcards
Define vaccination
Deliberate induction of an adaptive immune response to a pathogen by injecting a vaccine- a killed/attenuated form of the pathogen
Define immunisation
Deliberate provocation of an adaptive immune response by introducing an antigen into the body
What is meant by complete protection?
Lifelong immunity
What is meant by partial protection?
Requires boosters (some microbes/vaccines do not induce a strong enough immune response)
How is memory established for specific pathogens?
Generation of memory T and B cells
What is active immunisation?
Administration of micro-organisms or toxoid/purified antigen etc. to invoke an immune response matching that of natural infection, usually present little or no risk to recipient
What is passive immunisation?
Administration of performed antibody to recipient for prevention of infection (temporary)
Describe passive vaccination
- Usually very available
- Short-lived and temporary
- Given IM- contain antibody aggregates and other serum products- can activate complement if given IV- anaphylaxis
What are the sources of passive vaccination?
- Almost all blood products
- Homologous pooled human antibody
- Homologous human hyperimmune globulin (Rabies, CMV)
- Heterologous hyperimmune serum (anti-toxin- produced in animals)
- Transplacental- important in infancy
Describe active vaccination
- Long lived- similar to natural infection without risk of disease
- Live attenutated
- Inactivates
- Detoxified endotoxin (toxoid)
Describe live attenuated vaccine
- Attenuated form of natural virus/bacterium
- Must replicate
- Immune response similar to natural- few doses needed
- Can induce severe reactions
- Requires careful storage
Describe inactivated vaccine
- Cannot replicate
- Generally not as effective as live vaccines
- Requires multiple doses
- Mostly humeral (B cell antibody) responses
- Antibody titres reduce over time
What are the different types of inactivated vaccine?
- Whole- entire organism used
- Split- detergent lysed
- Subunit/ recombinant/ polysaccharide/ conjugate- purification of most immunogenic antigens
What is the tetanus vaccine directed against?
Tetanus toxoid
How are B and T cells activated with the tetanus vaccine?
- Dendritic cells present toxoid peptide antigen to CD4 T cells in lymph node
- Activates T Helper cells
How are toxoid specific antibodies generated with the tetanus vaccine?
- Activated B cells differentiate into plasma cells
- Secrete toxoid-specific antibodies
- Generate B cell memory
Why does the Tetanus vaccine require multiple doses?
- Not very immunogenic
- Only activates humeral response and a weak T cell response
What does the tetanus vaccine need to induce an effective response?
Adjuvant- alum
What type of vaccine is the MMR vaccine?
Live attenuated (trivalent)
How are T and B cells activates in the MMR vaccine?
- Dendritic cells present viral peptide antigen (bound to MHC 1 and 2) to T cells
- Activated CD4 helper and CD8 cytotoxic T cells- unlike tetanus
- Binding to viral antigen by BcR activated B cells
How is the adaptive response activated with the MMR vaccine?
- T cells traffic to site of infection
- Virus-specific antibodies migrate to infection site
Why is the MMR vaccine effective?
Induces protective immunity- requires a few doses
What is the MMR vaccine not suitable for?
Immunocompromised
