Measles & Vaccination Flashcards
why do we have vaccination
establish herd immunity
what is measles caused by
measles virus
why is there still measles but can’t spread
R0<1 - cases can arrive from different countries but we have established herd immunity
why is measles scary
highly infectious - high R0 - need to vaccinate large % of population
not highly virulent
in countries without adequate healthcare/malnutrition
high mortality (foreign aid cuts)
measles is the leading cause of
vaccine preventable death
measles virus mode of action
- enter host (only reproduce inside cell - gets in through respiratory system)
- infect macrophages (WBC - circulate blood/air sacs) = measles virus evolved to withstand + travel within them
natural killer cell - kills virus infected cells (innate IS, rapid response - from birth) = activate dendritic cells
- escape via dendritic cells (take fragments to lymph nodes)
- reach lymph nodes - multiply in B + T cells
- infect many organs
adaptive immunity
slow response - measles antibody production over time (not all dendritic cells infected -> defence mechanisms)
=life long immunity
measles complication
confections (malaria, Tb, HIV)
dehydration + malnutrition
*gets into gastrointestinal tract
advantage of measles virus
only one serotype = surface antigen proteins don’t change (//change can’t get into cells)
rhinderpest
eradicated - found in wild animal population = can’t persist - not dense enough
antigen
molecule that can stimulate an immune response
antibody
proteins that are found in blood of vertebrates - used by immune system to identify and neutralise foreign objects (bacteria/viruses)
how do antibodies work
- clump (multiple binding sites - agglutinate)
- bind (block)
- act as signal
clonal selection of B cells
antibodies meet complementary antigen = multiply
produce memory cells - secondary immune response is faster
types of vaccine
- different (but related) pathogens -cow/smallpox
(1 serious human disease/1 not) - dead pathogens - inactivated polio vaccine
(kill pathogen/leave surface antigen intact) - weakened(attenuated) pathogens - measles
- Recombinant pathogens
innate immune system
- macrophage
- natural killer cells
- denditric cell
adaptive immune system
- B-cell
5. Killer T-cell
infected cell
displays fragments of virus on its surface
activated killer T-cell recognises the complex using its T-cell receptor and kills infected cell
why is sabin polio virus used (oral/attenuated)
convenience
low cost
efficiency
HIGHER risk = live vaccines can evolve
if we have a dead vaccine
cause clonal selection of: B cells
leading to production of: Antibodies
and these long lasting cells: Memory B cells
if we have a live but attenuated vaccine
cause clonal selection of: B cells + T cells
leading to production of: Antibodies + Killer T cells
and these long lasting cells: Memory B cells + Memory T cells
why do we not have a vaccine against aids
look at immune response of people who recover from diseases naturally (measles) - no natural survivors of HIV/AIDS
why are we seeing a decline in vaccination rates
- disease are no longer seen = no longer feared
- a growing distrust of government
- the media (power to change behaviour - selective news/power to change behaviour)
