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Module 3 > Introduction to Vaccines > Flashcards

Introduction to Vaccines Flashcards

1
Q

Define a vaccine

A

Something that stimulates the immune system without causing harm or side effects

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2
Q

What is the aim of vaccines

A

To provoke immunological memory to protect individual against a particular disease

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3
Q

What is the difference between something that is immunogenic and reactogenic

A

Immunogenic - ability to start an immune response

Reactogenic - ability to cause reaction

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4
Q

Define an antigen

A

Anything that causes an immune response

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5
Q

What is in a vaccine?

A
  • Antigen
  • Adjuvant (normally alum)
  • Stabilisers (PBS)
  • Water
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6
Q

What types of antigen can you use in a vaccine (5)

A
  • Inactivated Protein
    • Tetanus toxoid
  • Recombinant protein
    • Hep B
  • Live attenuated pathogen
    • Polio/BCG
  • Dead pathogen
    • Split flu vaccine
  • Carbohydrates
    • S. pneumoniae
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7
Q

What is the MOA of inactivated toxoid vaccines

A

Inactivated toxin induces antibodies which block toxin binding to nerves

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8
Q

What are some advantages of Inactivated toxoid vaccines

A
  • Cheap
  • Well characterised
  • Safe
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9
Q

What are some disadvantages of Inactivated toxoid vaccines

A
  • Requires understanding of toxin moa
  • Not all organisms encode toxins
  • Small risk of failure to inactivate (some impurities)
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10
Q

How are recombinant protein vaccines made

A
  • Surface antigen gene isolated
  • Gene inserted into yeast
  • Modified Yeast cells produce sAg
  • Purified into vaccine
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11
Q

What is the MOA for recombinant protein vaccines

A

Induces classic neutralising antibodies

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12
Q

What are the advantages of recombinant protein vaccines

A
  • Pure
    • Useful if we know surface antigen
  • Safe
    • Low strain variation
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13
Q

What are some disadvantages of recombinant protein vaccines

A
  • Relatively expensive
  • Doesn’t work for everything
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14
Q

How are dead pathogen vaccines made

A

Whole pathogen can be chemically killed

These are innoculated into eggs

Vaccine purified from eggs

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15
Q

What is the MOA for dead pathogen vaccines

A

Induces antibody and T cell response

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16
Q

What are the advantages of dead pathogen vaccines

A
  • Antigenic components are intact
    • Therefore, more immunogenic as other components are included
17
Q

What are some disadvantages of dead pathogen vaccines

A
  • Fixing/killing can alter chemical structure of antigen
  • Requires capacity to grow the pathogen (H5N1)
  • Vaccine induced pathogenicity
  • Risk of contamination with live pathogen (polio)
  • ‘Dirty’
18
Q

How are live attenuated vaccines made

A
  • Attenuation by serial passage
    • Comparison of end virus with orginical virus
  • Loss of virulence factors
19
Q

What is the MOA of Live attenuated vaccines

A
  • They replicate in situ
  • Trigger innate response and boost immune response
20
Q

What are the advantages of live atteniated vaccines

A
  • Induce strong immune response
21
Q

What are the disadvantages of live attenuated vaccines

A
  • Can revert to virulence
  • Can infect immunocompormised (BCG/HIV)
  • Attenuation may lose key antigens
22
Q

How are conjugate vaccines made

A

Polysaccharide coat component is coupled to an immunogenic carrier protein

23
Q

What is the MOA for conjugate vaccines

A
  • T cells only recognise peptides
  • B cells recognise conjugate (polysaccharide + carrier protein)
  • Processes and presents peptide antigen to CD4 cells
  • CD4 T cell releases mediators which elicit memory in B cells
24
Q

What are the advantages of conjugate vaccines

A
  • Improved immunogenicity
  • Highly effective at controlling bacterial infeciton
25
Q

What are the disadvantages of conjugate vaccines

A
  • Expensive
  • Strain specific
  • Carrier protein interference
  • Polysaccharide alone is poorly immunogenic
26
Q

Once the adaptive immune response is activated, what are the mechanisms in which they control the infection

A
  • Prevention of entry
    • Antibody blockade
    • Opsonisation -> phagocytosis
  • Boost T/B cell immunity
    • B cells activate T cells, T cells release mediators to boost B cell function
    • B cell produces Antibodies
  • Kill Infected Cells
    • CD8 cells recognise stressed cells
27
Q

What is meant by R0

A

The number of cases one case generates on average over the course of their infection period

28
Q

How can vaccines reduce R0

A

Herd immunity allows for transmission termination

Higher the R0, the higher the number of people you need to vaccinate

29
Q

What are some barriers to the development or compliance of vaccines

A
  • Development issues
    • Takes a long time to get from bench to bedside
  • Cost of product
  • Vaccine scares - anti-Vaxx
30
Q

What are the 2 areas of concern for vaccine complications

A
  • Acute responses
    • Fluvax
      • High cytokine release
  • Chronic complication
    • Pandemrix (?H1N1)
      • Narcolepsy
31
Q

What has stopped us from developing more effective vaccines?

A
  • High variation of target organism
    • Classic immune will only recognise one variant
      • HIV
  • Strain Replacement
    • One strain vaccinated, decrease in incidence, other strains increase in incidence
  • Natural infection can sometimes not be protective
    • HIV, CMV, TB
      • BEcause antigens are changing or hidden as in HIV
  • Flawed translation from animal models
32
Q

Vaccinations can increase the transfer of antibodies across the placenta to the baby. What time should the mother be vaccinated for flu or pertussis?

A

2nd or 3rd trimester

33
Q

With regards to flu vaccine, what is a novel approach for this therapy

A

Influenza changes all the time, the head portion changes

The stem of the haemagluttinin molecule remains more constant than the head

Could be potential target

Module 3 (17 decks)

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