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POM 4 Immunology > 4.12 Vaccination > Flashcards

4.12 Vaccination Flashcards

1
Q

What is a vaccine?

A

A substance used to stimulate the production of antibodies and provide immunity against one or more diseases

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2
Q

What is the aim of immunisation?

A

To provoke immunological memory and protect individuals against a particular diseases if encountered

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3
Q

What are some characteristics of the ideal vaccine?

A 
Safe
Easy to administer
Cheap
Can be stored for longer periods of time
Active against all variants
Life-Long protection
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4
Q

What three things can vaccines work to do?

A
  1. Prevent entry - vaccine stimulates production of antibodies which bind to virus and stop it harming cells
  2. Boosting immune response - the antigens in the vaccine stimulate CD4 Helper T cells
  3. Killing Infected cells - CD8 killer cells detect the foreign antigens
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5
Q

What are the characteristics of immune memory?

A

The memory cells can multiply much faster and produce a stronger immune response by generating antibodies which have a higher affinity for antigens

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6
Q

What is R0?

A

The basic reproduction number - the number of cases one case generates on average over the course of their infectious period

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7
Q

What happens if R0 <1?

A

The infection will die out ebventually

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8
Q

What happens if R0>1?

A

Then the infection will be able to spread in the population

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9
Q

What is the effective number and why is it more useful?

A

It is similar to R0 but does not assume that everyone is susceptible, and therefore takes into account that people may be immune - helpful as then the true severity can be determined

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10
Q

What is herd immunity?

A

Those people who are immunised against the virus can help protect those who are not as the virus will be less transmissible amongst those protected

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11
Q

What are the four components of a vaccine?

A

antigen
adjuvant
stabilising factors eg buffers
water

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12
Q

What is an adjuvant?

A

Substances used alongside the antigen to illicit a more robust immune response than if the antigen was just used alone

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13
Q

How do adjuvants work?

A

They engage with pattern recognition proteins which induce danger signals that activate DC’s to present antigen to T cells

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14
Q

What adjuvant is normally found in vaccines?

A

Alum

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15
Q

Mechanism of adjuvant action?

A
  1. Adjuvant stimulates DC
  2. DC take up antigen and moves to secondary lymphoid tissue
  3. Upregulation of co-stimulatory signalling and cytokines
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16
Q

What is an Inactivated Toxoid Vaccine?

A

A chemically inactivated form of toxin

17
Q

Benefits of inactivated toxoid vaccines?

A

Cheap, Safe

18
Q

Mechanism of Inactivated Toxoid Vaccines?

A
  1. Toxin binds to cell surface receptor
  2. Toxin/Receptor complex enters cell via endocytosis
  3. Dissociation of toxin releases active chain which causes the cell to be poisoned
  4. The neutralizing antibody are then produced, and blocks further binding of toxin to cell surface receptor
19
Q

How do recombinant protein vaccines work?

A

Surface antigen gene is isolated
Inserted into another organism
Modified cell produces antigen / vaccine
Induces classic neutralizing antibodies

20
Q

What are the disadvantages of a recombinant protein vaccine?

A

Expensive

21
Q

What is a live attenuated pathogen vaccine?

A

Vaccine where the pathogen has been weakened, but is still able to replicate so it can trigger an immune response, which is almost identical to what happens in a natural infection

22
Q

What is an example of an live attenuated pathogen vaccine?

A

MMR, BCG

23
Q

What are the advantages and disadvantages of a live attenuated pathogen?

A

Advantages: Strong immune response is generated
Disadvantages: Since it is a pathogen, it may infect the immunocompromised, can revert to virulence

24
Q

What is a dead pathogen vaccine?

A

Where the pathogen has been chemically killed by formalin, which induces antibody and T cell responses

25
Q

what is an example of a dead pathogen vaccine?

A

influenza

26
Q

What are some disadvantages of a dead pathogen virus?

A

killing the pathogen can sometimes alter the antigen

requires the capacity to grow the pathogen

27
Q

what is a conjugate vaccine?

A

Where the polysaccharide coat component is coupled to an immunogenic “carrier” protein which enlists CD4 help to boost B cell response to the polysaccharide, as B cell react strongly to the polysaccharides on some bacteria

The polysaccharide is considered a highly immunogenic part

28
Q

Conjugate vaccines involve T and B cells true or false?

A

False - only B cells

29
Q

Why do we need new vaccines?

A
  • changing demographics
  • changing environments
  • new diseases emerging
  • increasing resistance
  • old diseases we cant fix
30
Q

What type of vaccine is Diptheria?

A

Toxin Based

31
Q

What type of vaccine is MMR?

A

Live attenuated

32
Q

What type of vaccine is BCG?

A

Live attenuated

33
Q

What type of vaccine is Influenza A

A

Dead pathogen virus

34
Q

What type of vaccine is polio?

A

Live attenuated

35
Q

What are some barriers to future vaccine development?

A

Time, cost and expertise required to develop vaccines
Systematic challenges
Vaccine safety
Public expectation of free vaccination

36
Q

What makes it harder to generate vaccines?

A

Classic immune memory will only recognise one strain

Therefore vaccine antigens need to cover all the variety

37
Q

What are the phases of a clinical trial?

A

Pre-clinical

Phase 1 - safety in humans

Phase 2 - mixture of safety and efficacy studies

Phase 3 - shown to be safe and effective

FDA review (MHRA in UK) - licensing

Phase 4 - licensed and approved → then goes into large groups of people + more monitoring

38
Q

What needs to be considered for the scheduling of the vaccine?

A

Aim

Need

Scheduling with other vaccines

Availability

Cost

Population accessibility

Cultural attitudes and practices

Facilities available for delivery

39
Q

Give an example of a high variable virus?

A

HIV

POM 4 Immunology (14 decks)

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