Scientific Basis of Vaccines Flashcards

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1
Q

What is a vaccine

A

A biological substance that does not cause disease, which, when administered to the recipient, produces an adaptive immune response which provides protection against future disease

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2
Q

What are some consideration taken in vaccine development

A
  • What kind of protection is needed for this disease
  • When is the protection needed
  • Are memory cells required and what type
  • Where should the immune response take place
  • What kind of vaccine is neccesary
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3
Q

What are the main concepts of Jenners’s experiments

A
  • Challenge dose - proves protection from infection
  • Concept of attenuation
  • Concepts that prior exposure to agents boost protective response
  • Cross-species protection - antigenic similarity
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4
Q

What are the main aims for vaccination

A
  • Protection of the individual
  • Protection of the population - herd immunity
  • Eradication of Disease
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5
Q

Describe the vaccine paradox

A
  • The more we vaccinate the more dependant we are in reaching 95% vaccination for herd immunity
  • There is a lack of natural immune boosting
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6
Q

How long does it take for a primary response against an antigen to take place

A
  • 5-7 days for antibody response
  • 2 weeks for a full response
  • IgM to IgG switching memory B and T cells
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7
Q

How long does it take for a secondary response against an antigen to take place

A

With prior expose it takes around 7 days or less for a full protective response

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8
Q

What are the general principle with vaccines

A
  • Induce the correct type of response
  • Induce response in the right place
  • Duration of protection
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9
Q

What affect the vaccination protection duration

A
  • Is it needed for a short or long-term purpose
  • Are boosters needed for seasonal response
  • What type of infection is it
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10
Q

When should we vaccinate for infections

A
  • Vaccinate before 5 years for most vaccines
  • Maternal IgG antibodies from the placenta and IgA from breast milk may interfere with vaccines
  • Optimum timing for vaccination needs to be determined by experimentation
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11
Q

What are monotypic pathogens

A
  • Measles is serologically monotypic. Surface antigens have remained the same to date.
  • Vaccination or infection gives lifelong immunity.
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12
Q

What are polytypic pathogens

A

e.g. Influenza. Surface antigens change and immunity is readily overcome

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13
Q

What is antigenic drift

A

accumulation of mutations in genes that code for virus surface proteins with time

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14
Q

What is antigenic shift

A

Recombination of viral strains to produce a different subtype with a mixture of surface antigens from the original strains

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15
Q

Describe live attenuated organism type vaccines

A
  • BCG vaccine, Polio, MMR, Yellow fever
  • Live organisms which have had their virulence reduced
  • May require a cold chain (keep it cold) which may add to the cost
  • Concern of reversion to virulent state
  • Useful in inducing a CTL memory cell response
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16
Q

Describe inactiavted whole organism type vaccines

A
  • Influenza, Polio, Cholera, Hep A
  • Boosting is often required
  • Limited lifespan of vaccine
17
Q

Describe Sub-unit type vaccines

A
  • Present individual components of pathogens
  • Generally safer but can be hard to give an adequate response
  • Proteins, Toxoids, Peptides, Polysaccharides, Proteins
18
Q

How can we use bacterial toxins as vaccines

A
  • take toxins and inactivate with formaldehyde
  • Use it as a toxoid vaccine
  • Toxoid triggers immune response and produces antibodies
19
Q

How can we use bacterial capsular polysaccharides as vaccines

A
  • Tend to be poor antigens and they are short term and have no T cell response
  • Enhanced by using conjugation by attaching different components to the polysaccharides
20
Q

How do polysaccharide vaccines for

A
  • Provides B cell receptor with polysaccharide and induce a enhanced response
  • Activates T cell for an enhanced response
21
Q

What is the role of adjuvants in vaccines

A
  • enhance immune response to antigen
  • promote uptake and antigen presentation
  • stimulate correct cytokine profiles
22
Q

How was the eradication of small pox possible

A
  • No sub-clinical infections
  • After recovery, the virus was eliminated - no carrier states
  • No animal reservoir
  • Effective vaccine Slow spread, poor transmission
23
Q

Why is it hard to produce vaccines for some infection such as HIV/AIDS

A
  • There is a high mutation rate
  • Danger of reversion to virulence with live attenuated vaccine
24
Q

What are some examples of passive treatments

A
  • Passive immunity: maternal transfer
  • Treatment with antibody from another source: serum - Prophylaxis and/or treatment Rapid Short effect