Vaccines Flashcards
What part of immune response do vaccinations rely upon?
Immunological memory
Where do B memory cells develop and when?
Germinal centre of lymph nodes
After innate immune response (TFH activation)
Why do B memory cells provide quick, strong, long-lived immunity?
They are already class switch, have high affinity and are quiescent
What class of Ig dominates adaptive immune response?
IgG
What has longer lived memory, antibodies/cell mediated?
Antibodies
How was small pox first treated?
Variolation - taking pus from someone with less severe symptoms and giving it to healthy person
Why does the cowpox/small pox vaccine?
They both have similar surface antigens so the cowpox immunity works for small pox
What 4 things make an effective vaccine?
Safe
Protects against disease (induce antibodies and T cells)
Long-lived protection
practical considerations
Neutralising antibodies purpose?
Prevent pathogens entering cells that can’t be replaced
Are intracellular pathogens more effected by
a) cell mediated immune system
b) antibodies
a
Name 4 methods vaccines are based on?
Killed organisms
Attenuated
Recombinant
Conjugate
What is the basis of vaccines from killed organisms?
Negatives
Chemically treat the pathogen so it is no longer pathogenic (can’t replicate)
Need lots of copies of the virus and if not killed properly can cause pathology
What is an attenuated virus?
Virus that has been cultured and infected an animal e.g. monkey, until it acquires a mutation that means it doesn’t thrive in humans
Why are attenuated viruses effective as vaccines?
They mimic the natural course of infection without causing pathogenesis
Why are attenuated viruses not presented with MHC class I?
Don’t release cytotoxic molecules so they are not virulent
How are recombinant vaccines made?
Gene for the antigen is isolated and inserted into yeast and yeast are cultured
Modified yeast are selected fro and produce antigen, purified
Why is yeast used?
Replicates quickly and has a large chromosome
Why are recombinant vaccines safe?
Just an antigen so doesn’t elicit a response
Why can encapsulated bacteria evade the immune response?
Coated in peptidoglycan cells (no antigens on surface) so complement not activated (classical pathway) - no opsonisation so no phagocytosis
Why are capsular subunit vaccines not effective on children/elderly?
Made from purified specific polysaccharide antigens so doesn’t elicit a proper immune response - IgM only, no class switching, no somatic hypermutation, no memory, Th cells to activate B cells
What vaccine is used for encapsulated bacteria?
Conjuaget vaccines
What is the basis of conjugate vaccine?
Specific polysaccharide antigen chemically coupled with a carrier protein which amplifies the immune response by developing an environment in which T cells differentiate)
Why is injection a bad route of administration for most pathogens?
They normally enter via mucosal surfaces
Injection = systemic - systemic immune response may be inappropriate
Why is vaccine by injection not practical?
Expensive, requires skill and pain
Why are adjuvants used in vaccines?
Purified antigens do not elicit a strong immune response
Adjuvants are added to elicit inflammation and mimic natural infection to get a better response
