vaccination Flashcards
vaccines: explain the meaning of the following types of vaccine, giving a specific example of each; live attenuated, inactivated, subunit, toxoid, conjugate
define live attenuated vaccine
vaccine created by reducing the virulence of a pathogen, but still keeping it viable
describe the process of attenuation
pathogenic virus isolated and cultured in human cells; after some time used to infect monkey cells, and over time mutations are acquired to grow well in monkey cells; upon re-infection of humans, the virus does not replicate or infect well as adapted to monkeys
describe engineered attenuation
hypothesis driven reverse genetics could be used to engineer in weakness to viruses, attenuating the strain
describe poliovirus attenuation
sequencing allowed for key bases in attenuation to be identified; allowed for engineering of better vaccine
4 characteristics of viral vaccine production
retains antigens; stops replicating and causing disease; leads to natural immune response without symptoms
besides live attenuated vaccines, name 3 others
inactivated, purified, cloned
pros of live attenuated vaccines
rapid, broad and long lived immunity; dose sparing; cellular immunity
cons of live attenuated vaccines
requires attenuation - if over-attenuated then reduced levels of immunity; may revery if mutations reverted to normal state
pros of inactivated vaccines
safe; can be made from wild type virus
cons of inactivated vaccines
frequent boosting doses required; high doses needed for immune system to react
define toxoid vaccine
vaccine made from toxin that has been made harmless but that elicits an immune response
define conjugate vaccine
vaccine composed of polysaccharide antigen fused to a carrier molecule to enhance stability and effectiveness