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immunology > vaccines > Flashcards

vaccines Flashcards

1
Q

what are the different forms of vaccine agent that can be used

A 
live attenuated
whole inactivated
subunit
peptides
DNA vaccine
recombinant viral vectors
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2
Q

what is passive immunisation

A

the transfer of preformed antibodies from an immunised source into the circulation

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3
Q

what sera is usually used in passive immunisation

A

horse sera

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4
Q

what are the advantages of passive immunisation

A

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

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5
Q

what are the disadvantages of passive immunisation

A

does not activate immunological memory
no long term protection
possibility of reaction to anti sera

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6
Q

what happens in live attenuated vaccines

A

the pathogen is altered to reduce virulence by maintaining on specific medium to reduce virulence

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7
Q

are live attenuated vaccines still able to replicate

A

yes but at a reduced rate

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8
Q

can live attenuated vaccines cause a infection

A

yes can produce a short lived infection by can be cleared by host without harmful outcome

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9
Q

what are the advantages of using live attenuated vaccines

A

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

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10
Q

what are the disadvantages of using live attenuated vaccines

A

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

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11
Q

what is meant by whole inactivated vaccine

A

the organism is rendered inactive and inviable by heat. cant replicate

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12
Q

what are the advantages of whole inactivated vaccines

A

no risk of infection
storage is less critical
a large range of different antigenic components are present so a good immune response is possible

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13
Q

what are the disadvantages of whole inactivated vaccines

A

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

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14
Q

why is heat treatment not preferred to inactivate pathogens

A

can alter conformation of target antigens

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15
Q

what do modern approaches do to inactivate pathogens

A

exploit recombinant DNA technology to remove genes that control virulence but leave intact genes for infection

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16
Q

what are subunit vaccines

A

molecular components are purified and used as the immunogenic agent

17
Q

what are the 3 types of subunit vaccine

A 
inactivated exotoxin (toxoids)
capsular polysaccharides
recombinant microbial antigens
18
Q

a number of important pathogens produce the symptoms of a disease as a result of ____________

A

exotoxins

19
Q

what is 2 examples of pathogens that produce symptoms due to exotoxins

A

diptheria and tetanus

20
Q

what is a toxoid

A

heat treated or chemically modified exotoxin to eliminate toxicity

21
Q

what might capsular polysaccharides interfere with

A

bacterial interactions with phagocytes by blocking opsonisation

22
Q

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

A

conjugated

23
Q

what is the aim of using synthetic peptides as vaccines

A

to produce a peptide that include immunodominant B cell epitopes and can stimulate the memory T cell development

24
Q

what are the difficulties in using synthetic peptides as vaccines

A

now clear that the knowledge of HLA presentation of peptides is essential
peptides can be stimulatory or suppressive
most B cell epitopes are comformational

25
Q

what are the advantages of subunit vaccines

A

safe
only portions of pathogen are used
no risk of infection
may be easier to store and preserve

26
Q

what are the disadvantages of subunit vaccines

A

immune response is less powerful that to live attenuated vaccines
repeat vaccinations needed and adjuvants
subunits have to be chosen that elicit a response in the widest range of subjects

27
Q

what are 2 examples of adjuvants

A

aluminium salts

oil emulsions

28
Q

what can alum do

A

may extend the half life of an immunogen in site of infection

29
Q

what do adjuvants act as

A

delivery system and immune stimulators. essentially trigger the innate immune response (TLR, PRR, DAMPs PAMPs)

30
Q

whats an example of an adjuvant that has been used more recently in human

A

toll like receptor agonists

31
Q

high efficiency of adding adjuvants can be accompanied by safety hazards such as:

A

risk of inappropriate immune response

chronic inflammation

32
Q

what are the aims of DNA vaccines

A

to transiently express genes from pathogens in host cells generating an immune response similar to natural infection

33
Q

what are the advantages of DNA vaccines

A

do not require complex storage and transportation

delivery can be simple and adaptable to widespread vaccination programs - use of DNA gun

34
Q

what are the disadvantages of DNA vaccines

A

there is no transient infection

DNA vaccination is likely to produce a mild immune response and require subsequent boosting

35
Q

what are the aims of recombinant vector vaccines

A

to imitate the effects of transient infection with a pathogen but using a non pathogenic organism

36
Q

how are recombinant vector vaccines formed

A

genes for major antigens are introduced into a non pathogenic or attenuated microorganism and introduced to host

37
Q

what are the advantages of recombinant vector vaccines

A

creates ideal stimulus to immune system
produces immunological memory
flexible - different components can be engineered in
safe relative to live attenuated

38
Q

what are the disadvantages to recombinant vector vaccines

A

require refrigeration for transport
can cause illness in comprimised individuals
immune responses to virus in subjects can negate effectiveness

immunology (3 decks)

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