Vaccines Flashcards
Define variolation
The deliberate infection of smallpox
What did Edward Jenner do?
Introduced first vaccine for smallpox
1796 infected a young boy with cowpox in hope of preventing another infection of smallpox
Define herd immunity
When the population of immune individuals in a population reaches threshold, the spread of the disease to the non-immune population can be interrupted
How does vaccination work?
When we are exposed to pathogens for the first time we have no B cells in our body to produce the IgG that we need
As a result the infection can progress into disease
Overtime we produce specific IgG antibodies I.e. memory response
Next time we are exposed - rapid immune response because we can recognise it and it will not progress to disease
What are the 3 outcomes of being infected with disease?
1) survive and recover from illness
2) survive and have long term disabilities
3) do not survive
Name the type of vaccines
Live - attenuated vaccines
Inactivated
Recombinant subunit
Toxoid
Conjugate polysaccharide-protein
Define live attenuated vaccines and give and example
Vaccines derived from wild or disease causing, virus or bacteria are attenuated or weakened in a lab usually by repeated culturing
In order to produce an immune response the live attenuated vaccine need to replicate in the vaccinated person
What are the advantages of live attenuated vaccines?
Cheap
Adjuvants not necessary
What are the disadvantages of live attenuated vaccines?
Potential to cause pathology
Stability
Define inactivated vaccines
These vaccines are produced by growing the bacteria or virus in culture media then inactivating it with heat and/or chemicals
Not alive can’t replicate
Usually though chemical or heat to kill it
Need higher doses as they are less antigenic - potency is also lower
Also need boosters - for long term protection from the mature B cells
What are the advantages of inactivated vaccines?
Safer - not alive
Improved stability - already dead - storage doesn’t have a negative effect on the vaccine
What are the disadvantages of inactivated vaccines?
Costly - extra steps
Hypersensitivity
Define recombinant vaccines and give examples
Comprised of one antigenic part of the pathogen
Produced recombinantly - other microbes are programmed to produce the desired ANTIGENIC compound
Exposing that protein to our immune system - produce the IgG antibody to that protein
Stimulate production of B cells with the assistance of T-helper cells
Example Hep B
Define toxoid vaccines
Toxoids are forms of chemically altered toxin that are no longer pathogenic
antibodies produced in the body as a consequence of toxoid administration neutralises the toxoid moiety produced during the infection rather than upon the organism itself
It’s essentially finding out what part of the bacteria causes the disease and neutralising that stoppping that from causing the disease
Define conjugate polysaccharide vaccines
Prepared from extra cellular fractions
Grow up the pathogen and it has its unique polysaccharides and will chop them off the pathogen -
Use chemistry to attach the polysaccharide to the carrier protein - the carrier protein is what is recognised by our immune system
The protein attached is what really stimulates the T cells and T cells can present the carbohydrate portion to the B cells and the B cells can generate carbohydrate portion to the B cells and the B cells can generate carbohydrate specific antibodies
The T cell can present the polysaccharide antigen and mature the B cell against the polysaccharide
