L22: Immunisation Flashcards
variolation vs vaccination
- variolation - variola = small pox
- vaccination - vaccinia = cowpox
founder of vaccines
edward jenner - cow pox blister pus injected into milkmaids arm
who developed the first laboratory vaccine
louis pasteur
attenuated
weakened
what is the principle of vaccination
production of AB ensures a secondary response eliminates pathogen quickly/prevents disease
an effective vaccine will generally
- elicit a protective AB response
- elicit a memory T cell response
What are the three types of vaccines, give an example of each
- whole live organisms: cowpox
- whole killed organisms: cholera
- components of organisms: Hepatitis B
whole live organism vaccines cause what type of exposure and how frequently must one be vaccinated
prolonged exposure, single dose effective at stimulating lifelong immunity
whole killed or component organisms exposure and immunity
brief exposure to antigens, three or more doses for effective AB response
what are polysaccharide vaccines
- very weak AB response to polysaccharide antigens
- T-cell independent antigens
- little immunological memory
conjugate vaccines
bacterial polysaccharide component attached to a good antigenic protein carrier
how do conjugate vaccines work?
- polysaccaride attached to carrier protein
- taken up by B cells
- protein digested and antigen presented to T cell
- T cells stimulated to provide help
- Converts into a T cell dependent antigen
- activated B cell produces antibody against polysaccaride antigen on the surface of the bacterium
Why are babies vaccinated
to ensure protection when maternal antibodies wane
vaccine efficacy considerations
strain variation - eg serogroup B vs C (vaccine effective against one but not the other)
define herd immunity by vaccination
Lowering the number of susceptible individuals in a population decreases the natural reservoir and transmission
Unvaccinated individuals can be protected if their individual chance of encountering a pathogen is low
