Introduction to vaccination L28

Question 1

brief history of vaccines

Answer 1

first scientifically discovered by Edward Jenner in 1796 for small pox

tested knowledge that mild cattle disease cowpox would protect against deadly human disease small pox after observation with milk maids

Question 2

what is passive immunity

Answer 2

this is the transfer of antibodies from an immune to non-immune individual
immediate short term protection
not producing own antibodies so no memory cells are formed

can either be natural or artificial

Question 3

natural passive immunity

Question 4

artificial passive immunity examples

Answer 4

antibody therapy - anti-venom, monoclonal antibodies
post exposure prophylaxis

Question 5

anti-sera and what it is used for

Answer 5

this is a serum that contains specific antibodies against a particular antigen

used to provide passive immunity, neutralise toxins, pathogens or venoms, and treat people exposed to disease

Question 6

how is anti-sera made?

Answer 6

1) inject an animal or human (typically horse or sheep) with an antigen

2) animal/human produces antibodies as causes an immune response

3) blood is collected at certain intervals, purified and serum is extracted

Question 7

applications of antibody transfers

Answer 7

rapid treatment during acute illness of patients like EBOLA, measles, rabies etc or for snake venom or toxins

or can be used as a preventative measure - yellow fever

Question 8

advantages of antibody transfers

Answer 8

quick acting and immediate protection - useful for emergiencies - which is important for some cases such as being infected with snake venom, need fast response

passive immunisation can support a deficient immune system which is good for high risk individuals or immunocompromised

no need for prior exposure , protecting individuals without them having to encounter the disease

Question 9

disadvantages of antibody transfers

Answer 9

antibody levels fall and protection fades within months - short term protection only as no memory cells produced

antibody treatments must be given via intravenous injection

can get serum sickness - especially with animal derived serums

antiseras are expensive and complicated to produce and store

Question 10

monoclonal antibodies mAB

Answer 10

identical antibodies produced by a single B cell clone that all target one specific antigen epitope

Question 11

how are monoclonal antibodies made?

Answer 11

1. fuse a specific B cell with a cancer cell - hydridoma
2. hybridoma produces larges amounts of one type of antibody
3. antibodies are harvested and purified

Question 12

how do monoclonal antibodies provide protection ?

Answer 12

neutralise pathogens and toxins by binding and blocking
triggers ADCC via Fc region
enhances phagocytosis
can be designed to target cancer cells, viruses, or inflammatory molecules

Question 13

advantages of monoclonal antibodies

Answer 13

single specificity
near unlimited supply of antibodies
even antibodies with very rare specificities can be isolated
antibodies can be manipulated / customised

Question 14

disadvantages of monoclonal antibodies

Answer 14

expensive to make
need IV infusion
can cause immune reaction
not long lasting

Question 15

why do we humanise a mouse monoclonal antibody

Answer 15

to reduce immunogenicity - to avoid human immune system from attacking it
and to make them suitable for therapeutic use in humans

Question 16

how to humanise a mouse monoclonal antibody

Answer 16

replace mouse antibody parts with human antibody sequences whilst keeping antigen binding sites CDRs intact

1. isolate mouse Ab genes and identify the CDRs region
2. graft mouse CDRs onto a human antibody framework
3. modify any necessary changes
4. express new humanised Ab in host cells
5. test for function

Question 17

modern ways of making monoclonal antibodies

Answer 17

directly from human B cells
phage display
EBV transformation
in vitro expansion and selection

Question 18

what are the principles of vaccination

Answer 18

1. to introduce the immune system to a pathogen in a controlled environment
2. cause the immune system to remember the pathogen and respond to it
3. enable immune system to effectively clear pathogen to prevent disease

Question 19

the ideal vaccine properties

Answer 19

long lasting immunity
safe
stable in field conditions
easy to store and administer
single dose
affordable and accessible to all
pathogen evolution proof

Question 20

live attenuated type of vaccine

Answer 20

these are vaccines made from weakened forms of pathogen that can replicate but do not cause disease in healthy individuals

ensures that it mimics natural infection, very long lasting immunity, required 1-2 doses and induces both humeral and cell mediated immunity

however risk in immunocompromised people, can revert back to virulent form and require cold storage

Question 21

killed whole organism type of vaccine

Answer 21

vaccines made from inactivated pathogens that cannot replicate but still trigger immune response

safer for immunocompromised people, easier to store, induced mostly humeral immunity and may require boosters

however, weaker immune response than live attenuated, often need lots of doses

Question 22

toxoid type of vaccie

Answer 22

toxin dervied from pathogen

Question 23

subunit type of vaccine

Answer 23

bacteria and viruses, purified protein or polysaccharides from cell wall

doesnt use entire virus or bacteria, just the components of pathogenic organisms - the pathogenic agents

good as no extraneous pathogen particles like DNA

however, proteins may differ when not in situ and production can be expensive

Question 24

vector vaccines

Answer 24

antigen genes inserted into the vaccinia virus genome with all virulent factors removed

example - Rabies virus G protein, hepatitis B surface antigen