immunity and vaccines Flashcards
what does it mean if a person is immune to a disease
-minimum concentration of antibodies in the blood
-have memory cells that carry out a secondary response and respond quickly to the antigen that has been present on a pathogen in a previous infection
how to pathogens produce new strains
by mutation
new antigens which are different shapes to the original ones (antigenic variability)
antibodies bind to antigens specifically due to their shapes the new antigen is not recognised so there is no immunity
what stimulates an immune response
an antigen from a pathogen even if the pathogen isn’t present to make the person ill this is the idea is vaccines
antigens in vaccines may be:
-present on dead or weakened microbes
-present of parts of the microbial cell eg fragments of a cell membrane
-produced by non-pathogenic microbes ed genetically modifies yeast
why would you carry out a vaccination program
-protect an individual eg rubella vaccination to protect girls
-to protect populations and wipe out diseases. pathogens will not be spread and may become extinct if they don’t have hosts. This is called heard immunity
how are vaccines produced
-growing bacteria in culture and then killing or weaken them (not possible for virus’ as they use a host cell and reproduce so vaccines are produced
by infecting chicken eggs)
-genetic engineering
why are most vaccines injected
as if you take them orally they would be digested in the stomach
what can the word vaccinations also be used for
injections that contain antibodies rather than antigens
what do antibody injections do
raise levels of antibodies immediately without waiting for an immune response
how do you give active immunity
inject dead viruses so the person produces their own antibodies
how to give passive immunity
injecting antibodies if there isn’t time to wait for an immune response
not long lasting
