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intro to clinical sciences phase 2 > vaccines > Flashcards

vaccines Flashcards

1
Q

what are the 3 types of traditional vaccines

A

whole killed

toxoid

live attentuated

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2
Q

2 types of immunisation

A

passive
active / vaccination

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3
Q

define passive immunisation

A

the administration of pre formed ‘immunity’ from one person or animal to another person

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4
Q

limitation of passive immunisation

A

only humoral (antibody) mediated

not work if cell mediated

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5
Q

advantages of passive immunisation

A

gives immediate protection

effective in immunocomproised patients

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6
Q

disadvantages of passive

A

short lived
possible transfer of pathogens
‘serum sickenss’ on transfer of animal ser

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7
Q

2 examples of passive immunisation

A

Human Normal Immunoglobulin (HNIG)

Convalescing serum eg SARS Co-V2

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8
Q

how is HNIG prepared

A

from pools of of at least 100 donors

contains antibody against measles, mumps, varicella, hepatitis A etc

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9
Q

how is convalescing serum prepared

A

pooled from people recovering from covid -19
but clinical trial result sugggests no overall increased efficiacy against virus using passive immunisation

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10
Q

what was he first ever vaccine against

A

small pox

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11
Q

3 main approaches to making a vaccine

A
  1. using a whole virus or bacterium
  2. using parts that trigger the immune system
  3. using just the genetic material
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12
Q

2 different types of vaccines

A

non living vaccines - whole killed and toxoids

l;i’ve attentuated vaccines

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13
Q

what is the whole microbe vaccine approach

A

inactivated vaccine
live attentuated vaccine
viral vector vaccine

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14
Q

how are bacteria and viruses inactivated

A

they are grown in vitro and inactivated using agents such as formaldehyde or B-proplonolactone

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15
Q

do non living vaccines cause infection

A

no but the antigens contained in it induce an immune response that protects against infection - by non self antigen recognition

non living vaccines can also be cell freee toxoids - inactivated toxins

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16
Q

problems and limitations of whole killed vaccines

A

The organisms must be grown to high titre in vitro (viruses and some bacteria difficult/expensive to grow in the lab)
• Whole pathogens can cause excessive reactogenicity (i.e., adverse reactions, excessive immunological responses)
• Immune responses are not always close to the normal response to infection, e.g., no mucosal immunity, no CD8 Tc responses
• Usually need at least 2 shots

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17
Q

4 examples of bacterial whole killed vaccines

A

diptheria

tetanus

pertussis

cholera

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18
Q

examples of viral whole killed vaccines

A

polio vaccine
influenza vaccine
hepatitis A vaccine
rabies vaccine
SARS - COV 2

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19
Q

what are live attentuated vaccines

A

The organisms replicate within the host and induce an immune response which is protective against the wild-type organism but does not cause disease.

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20
Q

benefits of live attenuated vaccines

A

more real life and provides better protection

Immune response more closely mimics that following real infection because its not fixed – no shape change.

Better immune response so lower doses are required, so the scale of in vitro growth needed is lower.

Route of administration may be more favourable (oral).

Fewer doses may be required to provide protection.

21
Q

what is attenuation

A

where an organism is cultured in such a way that it does not cause disease when inoculated ito humans

it has lost its pathogenicity but retains its antigenecity ie shape

22
Q

problems and limitations of live attenuated vaccines

A

often impossible to balance attenuation and immunogenicity

reversion to virulence

transmissibility

live vaccines may not be attenuated in immunocompromised hosts

23
Q

examples of bacterial live attenuated vaccines

A
  1. Bacille Calmette-Guérin (BCG) Mycobacterium bovis grown over many passages in vitro.
    Gives some protection against TB (tuberculosis)
  2. Salmonella typhi - temperature sensitive strain given orally.
24
Q

examples of viral live attenuated vaccines

A

poliomyeletis (SABIN)- widely used to brain g polio to extinction

vaccinia virus - used in billions of doses to eradicate smallpox

measles, mumps, rubella - MMR

25
Q

pathogens lacking vaccines

A

HIV, malaria, Schistosomiasis, Leishmania spp, Herpes Simplex Virus, CMV, RSV, Rhinoviruses, Group B streptococci, Meningococcus group B, M. leprae…….

26
Q

why do so many pathogens not have vaccines

A
  • pathogen too difficult to grow
  • killed pathogen not protective (shape change)
  • impossible to obtain attenuated and suitably imunogenic strain
  • too many strains causing disease
27
Q

what are 5 novel vaccine approaches

A
  • recombinant proteins
  • synthetic peptides
  • live attenuated vectors
  • mrna vaccines
  • polysaccharide protein conjugates
28
Q

what are recombinant proteins

A

genetically engineered and produced from bacteria, yeast, insect or mammalian cells

they avoid the problem of having to grow the pathogen in vitro

29
Q

what is the issue with recombinant proteins

A

major difficulties - finding a protein or proteins that are protective and generate a strong enough immune response

30
Q

examples of recombinant proteins on the market

A
  1. hepatitis B surface antigen
  2. HPV vaccines
  3. SARS -Co-V2
31
Q

what are synthetic peptides

A

peptides synthesised directly using a machine - avoids the need for pathogen growth

32
Q

3 problems with synthetic peptides

A

identifying protective epitopes
inducing a strong response
inducing a broad response

33
Q

are there any examples of synthetic peptides on the market

A

NO

34
Q

what are live attenuated vectors

A

composed of a safe living attenuated viruses that have inserted genes encoding foreign antigens, which are displayed to the immune system

35
Q

when can live attenuated vectors cause problems

A

in immunodeficiency people

36
Q

what are viral vectors

A

attenuated, genetically stable vaccine vector able to take additional foreign DNA encoding for the desired antigen/protein

37
Q

what are DNA vaccines

A

a mammalian plasmid containing DNA that encodes for the foreign protein of interest is injected directly

this requires a lipid nano carrier to get the dna into a human cell.

the dna goes to the nucleus, gets transcribed and the foreign protein expressed with MHC to stimulate the immune response

38
Q

advantages of dna vaccines

A

avoid the need to grow the pathogen, viral vector

no live organism involve

dna is cheap to produce

39
Q

problem of dna vaccine

A

often poor immunogenicity

40
Q

are there any examples of dna vaccines on the market

A

NO

41
Q

what are mrna vaccines

A

mrna of the target foreign protein is synthesised in vitro
it is complexed with lipid nano particles that stabilise and protect the mrna from degradation and allow the mrna to cross the plasma membrane

the mrna is translated int he cytoplasm and the protein presented on the surface of the cell with MHC

stimulationg the immune response

42
Q

benefits of mrna vaccines

A

avoid the need to grow the pathogen , viral vector
no live organism needed
mrna is relatively cheap to produce
quick to make new variations of vaccine

43
Q

examples of mrna vaccine

A

sars - co v2:

pfizer biotech, moderna, bayer curevac

44
Q

what are t indepdent antigens

A

bacterial capsular polysaccharides cannot be processesed and presented on MHC class II

No t cell help

antibody response of low magnitude

low affinity

predominantly igM

little or no boosting on secondary exposure

infants respond especially poorly and are major target group

45
Q

recent changes to vaccination programme

A
  1. addition of pneumococcal conjugate virus at 2,4, and 13 months
  2. a dose of Menc VACCINE AT 3 AND 4 months
  3. a booster dose of Hib and MenC vacccine at 12 months
  4. HPV for teenage girls and boys
  5. BCG no linger routinely given to teenagers. targeted on at risk infants
46
Q

are vaccines safe

A

currently no scientific evidence to link vaccination with any lo9g term disease

47
Q

why don’t people trust vaccines

A

misinformation on internet
religion
studies linking immunisation with contraction of other diseases

48
Q

stages of vaccinationm

A
  1. Engage the innate immune system
  2. Danger signals that activate the immune system, triggers such as molecular fingerprints of infection – PAMPs (pathogen associated molecular patterns)
  3. Engage TLR receptors
  4. Activate specialist APC
  5. Engage the adaptive immune system
    a. Generate memory T and B cells
    b. Activate T cell help

intro to clinical sciences phase 2 (48 decks)

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