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Infection Term 4 > 5.2-Vaccines > Flashcards

5.2-Vaccines Flashcards

1
Q

What are the two ways of acquiring immunity?

A

1) Active- Using our own antibodies

2) Passive- ready made antibodies

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2
Q

What are the two types of active immunity?

A

Natural- exposure to infectious agent

Artificial- immunisation vaccine

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3
Q

What are the two types of passive immunity?

A

Natural- maternal antibodies; temporary immunity in babies

Artificial- antibodies from other sources

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4
Q

When does passive immunity peak in infants?

A

prior to or around birth

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5
Q

Define vaccination

A

exposing a person to material that is an antigen but NOT pathogenic

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6
Q

Define antigenic

A

provokes an immune response

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7
Q

Define immunisation

A

process of inducing immunity to disease

immunity is normally acquired naturally but can be induced by vaccination

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8
Q

Who should NOT be vaccinated? (and thus relies on herd immunity?)

A
  • allergy
  • fever
  • HIV infection
  • immunodeficiency
  • IG admin
  • premature
  • thrombocytopenia
  • neurological disorder
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9
Q

Define herd immunity

A

The state achieved when immunisation programmes reach sufficiently high coverage of the larger population to interrupt transmission within the community

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10
Q

What 4 factors does herd immunity depend on?

A

1) degree to which disease is infectious
2) efficacy of vaccines
3) vulnerability of population
4) environmental factors

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11
Q

What is the purpose of herd immunity?

A

to collectively protect people unable to be vaccinated eg too young, health problems, pregnant
-it is not necessary for all the population to be immunised.

when a high percentage of population is vaccinated, chances of infectious diseases to spread are reduced, because there are not many people who can be infected

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12
Q

What are essential characteristics of a good vaccine?

A
  • effective protection against pathogen without significant risk of disease/ side effects
  • supply protection that is effective over a long time
  • stimulate development of immune responses eg T cell responses
  • stimulate production of neutralised antibodies to reduce risk of re-infeciton
  • stable for storage, transport and use
  • economically feasible for widespread use
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13
Q

What is poliomyelitis?

A

viral disease that may affect spinal cord causing muscle weakness and paralysis
-primarily an intestinal infection but can cause NS damage and paralysis in some small cases

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14
Q

How does poliomyelitis enter body?

A

it is an enterovirus ie enters through the gut
travels to lymph nodes and goes from NS to CNS

enters through mouth, usually from hands contaminated of an infected person

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15
Q

What are the 3 types of poliomyelitis?

A

1) Spinal
2) Bulbar
3) Bulbospinal

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16
Q

When is polio most common?

A

in the summer

affected middle class Americans

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17
Q

What type of virus in the poliovirus?

A

Enterovirus
non enveloped, positive sensed RNA virus
3 serotypes:
P1, P2, P3
P1 is the most common and virulent serotype

  • heat resistant, tolerates acidic environment, pH of 3-5 up to 3 hours
  • resistant to detergents and disinfectants
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18
Q

What are the signs and symptoms of poliovirus?

A

manifested through:

  • abortive poliomyelitis
  • nonparalytic poliomyelitis
  • paralytic poliomyelitis
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19
Q

What is the IPV SALK?

A

Inactivated Polio Vaccine made by Salk
ADVANTAGE: safety; if made properly, could not cause disease

ie was a whole agent vaccine, virus killed using heat or formaldehyde

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20
Q

What is the main disadvantage of the IPV Salk vaccine?

A

the formaldehyde used in its manufacture caused the immune system to recognise killed virus differently from live virus, possibly risking a shortened period of immunity,

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21
Q

What is the OPV Sabin vaccine?

A

Oral Polio Vaccine made by Sabin
-immediately after vaccination, people shed weakened virus in their faecal waste. This BOOSTED immunity for others in the community and gradually reduced the number of people susceptible to poliomyelitis

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22
Q

Benefits of the OPV?

A
  • easily administered by giving children a sugar cube containing the vaccine in liquid form
  • indirectly protects other susceptible individuals by secondary vaccination
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23
Q

RISK of OPV?

A

RISK of vaccine-association paralytic polio as a result of vaccination
-harder to manage than IPV because IPV is not live

24
Q

Benefits of OPV over IPV? ( You took this as a child!)

A
  • IPV induces only little immunity in intestinal tract
  • IPV is 5x more expensive
  • OPV does not require highly trained medical personnel to administer every dose
25
Q

What are ATTENUATED vaccines?

A

using a weakened form of the microbe

-process that lessens the virulence of a microbe

26
Q

Give 3 examples of attenuated vaccines

A

OPV Sabin
MMR
Influenza- Flumist

27
Q

Describe attenuation of viruses by passage through non-human cells

A

1) Pathogenic virus isolated from patient, grown in human cells
2)Infect monkey cells with cultured virus
3) Virus acquires many mutations that allow it to grow well in money cells
4) Mutations make virus unable to grow well in human candidate
therefore becomes a VACCINE CANDIDATE

28
Q

Describe the mechanism of an attenuated virus

A

viruses grown under lab conditions accumulate mutations that reduce virulence of microbes

  • live organism is injected and use replicate in the vaccinated individual over a period of time
  • immune system responds as it would to natural infection
  • does this without causing disease
29
Q

What are the risks with the use of attenuated viruses?

A
  • Immunocompromised may not be able to overcome weakened form
  • rare chance that the attenuated virus may mutate to a virulent form before recipient’s immune system is able to develop a response
30
Q

Name 2 bacterial attenuated vaccines

A
  • Typhoid

- BCG ( for TB)

31
Q

How do vaccines stimulate immune memory?

A

killed virus vaccine requires multiple doses (booster shots) to adequately stimulate a protective immune response.

  • live virus vaccines replicate in host, (disadvantage is virus will mutate and become immune later)
  • no requirement for boosters
32
Q

Give 3 advantages and disadvantages each for live vaccines

A

Advantages:

  • multiply like natural organism
  • require fewer doses and boosters
  • long-lasting

Disadvantages:

  • special storage
  • back mutation
  • side effects
33
Q

What are toxoids?

A

inactivated vaccine that uses the toxin proteins that some bacteria produce

  • toxins are purified and treated with aluminium salts ( OR heat) to produce a weakened form of the toxin
  • the injected toxoid will stimulate B cells to produce antibodies to bind to and inactivate the toxin during a real attack
34
Q

Give 2 examples of toxoids

A
  • tetanus
  • diphtheria
  • whooping cough
35
Q

Purpose of toxoids

A

to build immunity against toxins, but not necessarily the bacteria that produce the toxins

36
Q

What are the advantages and disadvantages of toxoids?

A

Advantage: does not cause disease

Disadvantages: not highly immunogenic
-may require multiple doses

37
Q

What are DNA vaccines?

A

create a recombinant plasmid containing a gene encoding a specific antigen

Engineer in sequences:

  • enabling it to be expressed in humans
  • passaged through bacteria

introduce into humans+ let human cells produce antigen and present to T cells and provoke immune response

38
Q

Recombinant vaccines

A
  • genetic engineering approach
  • Hep B
  • Vccina or adenovirus alteration
39
Q

What are subunit vaccines?

A

do not contain live components of the pathogen

-they differ from inactivated whole-cell vaccines, by

containing ONLY the ANTIGENIC PARTS of the pathogen

40
Q

What are the three types of subunit vaccines? (PPC)

A

1) Protein based
2) Polysaccharide
3) Conjugate

41
Q

What are protein-based vaccines?

A

specific isolated protein of the pathogen is used

42
Q

What is a disadvantage of protein-based vaccine?

A

If protein is denatured, immune response may be inadequate

43
Q

Give example of a protein based vaccine

A

Hep B Vaccine; surface antigen HBsAg

Acellular pertussis; inactivated pertussis toxin and bacterial components

44
Q

What are polysaccharide vaccines?

A

polysaccharide from cell wall of bacteria is used; this exposes immune system to that particular type of polysaccharide

45
Q

What are the disadvantages of polysaccharide vaccines?

A

they are T-cell independent ie stimulate B cells without stimulating T Helper cells therefore no antibodies produced

-poor immune response in < 2yrs olds

-only short term immunity (no immune memory)
no booster response even after repeated injections

46
Q

Name 2 examples of polysaccharide vaccines

A

Typhoid VI polysaccharide vaccine

Pneumococcal polysaccharide vaccine

47
Q

What is a conjugate vaccine?

A

polysaccharide from cell wall of bacteria is used AND a carrier protein (conjugation)

-carrier protein helps it be exposed to immune system better+ helps immune system create a stronger response

48
Q

What is the impact of conjugate vaccine on the immune response?

A

goes from T cell independent to T cell dependent immunity

1) Increased immune response< 2 years ago
2) Booster response to multiple doses

49
Q

What are some examples of a conjugate vaccine?

A
  • Hib

- Pneumococcal Conjugate Vaccines (PCV-10, 13)

50
Q

What are subunit vaccines?

A
  • single antigen or mixture of antigens
  • safer (cannot reproduce)
  • however, often less effective than whole agent vaccines
  • can be costly
  • always require boosters
  • types of carrier proteins/ conjugates used can produce different effects
51
Q

How can subunit vaccine problems be overcome?

A

1) Multiple doses-booster shots
2) Use adjuvants;
- prolongs stimulation of immune response
- works by trapping the antigens in a chemical complex and releases them slowly

52
Q

What are adjuvants?

A
  • substances or mixtures that are given together with a vaccine to heighten the effectiveness of the vaccine
  • in order for vaccines to be successful and elicit an immune response, they need to be detected by host as both foreign and dangerous.
  • introduction of foreign proteins from micro-organisms to provide the danger signal
53
Q

What do adjuvants do?

A

-prolong period of time the vaccine is able to stimulate immune responses and/ or attracts phagocytosis cells/

eg ALUMINIUM HYDROXIDE

54
Q

Does the HPV vaccine use and adjuvant?

A

uses a modified version of LPS called MPL ( Monophosphoryl lipid A)

HPV (cervarix)

55
Q

What are aluminium salts used in?

A
  • DTaP
  • HepA
  • HepB
  • HPV
  • MMR
  • rabies
  • rotavirus
  • rubella
56
Q

Name 5 common routes of administration of vaccines?

A
  • Deep subcutaneous or intramuscular route
  • Oral route (oral BCG vaccine)
  • Intradermal route ( BCG vaccine)
  • Scarification (small pox vaccine)
  • Intranasal route ( live attenuated influenza vaccine)

Infection Term 4 (8 decks)

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