what are the different forms of vaccine agent that can be used
live attenuated whole inactivated subunit peptides DNA vaccine recombinant viral vectors
what is passive immunisation
the transfer of preformed antibodies from an immunised source into the circulation
what sera is usually used in passive immunisation
horse sera
what are the advantages of passive immunisation
can quickly neutralise toxins and venoms
conventional immune response may be too slow
in the case of highly virulent pathogens (ebola) immunised animals may be the only means of treatment
what are the disadvantages of passive immunisation
does not activate immunological memory
no long term protection
possibility of reaction to anti sera
what happens in live attenuated vaccines
the pathogen is altered to reduce virulence by maintaining on specific medium to reduce virulence
are live attenuated vaccines still able to replicate
yes but at a reduced rate
can live attenuated vaccines cause a infection
yes can produce a short lived infection by can be cleared by host without harmful outcome
what are the advantages of using live attenuated vaccines
sets up transient infection
activation of full immune response
stimulation of memory response in T and B cells
antigens are released over time as it is able to replicate so only one immunisation is required
what are the disadvantages of using live attenuated vaccines
immunocomprimised patients may become infected
can sometimes revert to virulent form which in areas of poor sanitation can lead to outbreak
live organisms need to be refrigerated for stable storage
what is meant by whole inactivated vaccine
the organism is rendered inactive and inviable by heat. cant replicate
what are the advantages of whole inactivated vaccines
no risk of infection
storage is less critical
a large range of different antigenic components are present so a good immune response is possible
what are the disadvantages of whole inactivated vaccines
tend to just activate humoral immune response
lack of T cell involvement
without transient infection immune response can be quite weak
repeated booster vaccinations are required
why is heat treatment not preferred to inactivate pathogens
can alter conformation of target antigens
what do modern approaches do to inactivate pathogens
exploit recombinant DNA technology to remove genes that control virulence but leave intact genes for infection
what are subunit vaccines
molecular components are purified and used as the immunogenic agent
what are the 3 types of subunit vaccine
inactivated exotoxin (toxoids) capsular polysaccharides recombinant microbial antigens
a number of important pathogens produce the symptoms of a disease as a result of ____________
exotoxins
what is 2 examples of pathogens that produce symptoms due to exotoxins
diptheria and tetanus
what is a toxoid
heat treated or chemically modified exotoxin to eliminate toxicity
what might capsular polysaccharides interfere with
bacterial interactions with phagocytes by blocking opsonisation
in some cases the target antigen (eg capsular polysaccharides) may only stimulate a weak T cell response. this reduceds the induction of immunological memory. to overcome tis they can be chemically ______ to a second antigen
conjugated
what is the aim of using synthetic peptides as vaccines
to produce a peptide that include immunodominant B cell epitopes and can stimulate the memory T cell development
what are the difficulties in using synthetic peptides as vaccines
now clear that the knowledge of HLA presentation of peptides is essential
peptides can be stimulatory or suppressive
most B cell epitopes are comformational
