WEEK 10: 10.5 Vaccination Mechanics Flashcards
(27 cards)
What is a vaccination
uptake of a vaccine (injection/oral) and is a weak form (attentuated) of part of (a protein or nucleic acid) an infectious agent
What is immunisation?
the process of getting the vaccine and becoming immune to the disease following vaccination
What does the effectiveness of immunisation depend on?
dosage, age, site of administration, no of doses
What kind of immunity is activated when an individual is vaccinated?
Adaptive immunity, hence they must bypass static, soluble and cellular barriers, and be taken up by T and B cells
Where are vaccines activated (naive T and B cells encounter the antigen and maybe get activated)?
In secondary lymphoid organs - spleen, lymph nodes and MALT
Is natural immunity preferrable and why?
Yes as once infected, normally you will acquire immunity and memory against the infectious agent (Humoral and cell-mediated immunity).
Then why are people vaccinated despite natural immunity being preferrable?
-chance of falling ill is high
- immune system is quite slow,
- it is important to prime the adaptive immune system before natural infection (they have seen the antigen in another form, learn and improve immune response to antigen)
- Lessens the severity of disease
How is immunisation different/similar to natural immunity?
Different if you use a live-attenuated, mRNA pathogen, as it enters the host cell, very similar to the pathogen but slightly less dangerous MIMICS as it activates humoral and cell mediated immunity
Similar is when it activates solely humoral immunity, and the antigen is just an inactivated whole organism
What are different types of vaccines?
USES WHOLE ORGANISM (virus/bacterium):
Live-attenuated vaccines
Inactivated vaccines
USES PART OF ORGANISM (virus/bacterium):
Purified subunit vaccines
Cloned vaccines
What is a drawback to whole organism vaccines?
Variations in the antigen from vaccine to vaccine - can be dangerous or not effective enough
What is a benefit of part of organism vaccines
Very specific part of antigen, less variation and more predictable effect on patient
What is a drawback of part of organism vaccines
T and B cells exposed to a small amount of antigen (eg. isolated components of microbe like proteins/polysaccharides) - is it effective enough?
How do vaccines stimulate antibody production? (many stepss)
- vaccine introduced to body
- vaccine uptaken by dendritic cell
- vaccine processed and presented on MHC class II (or MHC class 1) to naive CD4 cells
- CD4 cells activate and differentiate into effect T helper cells (which activates plasma B cells + coordinate communication via cytokines)
- B cell recognises vaccine independently and presents it on MHC class 2 (can bind bits and pieces on the antigen themselves)
- Th cell activates B cell that recognises vaccine as well
- B cell proliferates and diffs into IgM producing plasma cells and IgG expressing memory B cells
- Clones of memory B cells mean there is more than one B cell that can now recognise the infectious agent
- When IgG memory B cells recognise the infectious agent again they diff into plasma cells releasing IgG antibodies to neutralise the agent
- IgG has higher affinity for the antigen
- After a while (ten days), memory cell recognised antigen, get acitvated, undergo clonal proliferation, diff into plasma cell and more memory cells
- Lotss of plasma cells are created and they secrete a lot of things -> much quicker response 2-3 days and a higher amplitude of response- secondary immune response is also much likely to be better
Where do secreted IgG antibodies go>
they leave the lymph node, enter circulation and immobilise the antigen
Why is the secondary immune response is also much likely to be better once vaccinated?
IgG and IgM have a higher affinity to the antigen
What is a live attentuated vaccine
the whole organism is grown in lab conditions hence they become complacent hence each time the culture changes (passaging through cell cultures) the virus weakens (no longer virulent)
It results in an organism that can still attach onto original host cell but unable to cause disease as they can’t replicate
What is pros and cons of live attenuated vaccine
pros: might be a single dose and imparts life long humoral immunity and CMI
cons: could revert to wild type (virulent)
What is an inactivated vaccine?
Grow the whole organism in lab condition, and as it’s grown its harvested and demolished (exposed to heat, chemicals or radiation). Rich antigen-wise but very safe
What are pros and cons of inactivated vaccines?
pros: stimulates humoral immunity & no reversion to wild type (virulent)
cons:
little to no cell mediated immunity
more than one dose required
contains egg product
What are purified subunit vaccines?
Isolate one part of the pathogen (toxoid, polysaccharide protein)
What are pros and cons of purified subunit vaccines
pros:
- stimulate humoral immunity
- no chance of reverting to wildtype
cons:
- little to no cell mediated immunity
- more than one dosage needed
What are cloned vaccines?
Get isolated genetic material and produce recombinant products like DNA, mRNA or proteins
Pros and cons of cloned vaccines?
pro: stimulate humoral immunity and no chance of reversion
cons: multiple doses needed
What is an adjuvant? provide examples
a substance that enhances the immune response
alum, lipid A
