27 Vaccination Flashcards
what is active immunisation
Administration of antigen in order to induce active production (takes time to generate response) of immunity and thus protection from disease
what immunity is created following active immunisation
specific for antigen given
is immunological memory is induced following active immunisation
yes
what does immunity involve for active immunisation
AB and/or T cell responses
what immunity can be induced following active vaccination
systemic and/or mucosal immunity
when is the protection in place following active immunisation
not immediate
what is the first ever virus eradicated
small pox
what is variolation
in china - potentially dangerous, scrap the scab and powder it in hope it would act as a protection
what was the cowpox vaccine like
not variolation - as not using material from the organism itself
why did the cowpox cure smallpox
elicit proteins of cowpox, can bind to smallpox virus and stop it infecting
what is the initial response following infection/vaccination
IgM
whay is herd immunity
more vaccinated against it in community the harder it is to spread
what are live attenuated vaccines
Organisms whose virulence has been reduced e.g. by repeated culture in vitro
what do live attenuated vaccines cause
Multiply in host, mimicking natural infection but causing no/mild symptoms
Immune response mimics that generated by natural infection
what are the risks of live attenuated vaccines
- potential for severe infection in immunodeficiency
- potential to revert to virulent strain
- storage conditions critical for stability
what immunity is induced following live attenuated vaccines
systemic/mucosal immunity
long lasting memory
what is the problem with live attenuated vaccines
not suitable/possible for all viruses
examples of live attenuated vaccines
MMR
BCG
what is the effect when vaccinated with killed viruses
Preparations of whole inactivated virus/bacteria
Don’t multiply in host
what is the immunity induced following killed vaccines
Usually only systemic immunity induced
how many doses of live attenuated are required
one
how many doses of killed vaccines are required
several doses
what is the risk with killed vaccines
Large amount of antigen needed – risk of reaction – partly overcome by using adjuvants
- inactivation process may alter structure
- not suitable for all organisms
what are the ‘no risks’ with killed vaccines
no risk of infection (unless faulty inactivation)
no risk of reversion to virulence
tend to be more stable for storage
examples of killed vaccines
killed polio (salk) influenza
what is the effect mixing an antigen with adjuvant
good response
what is the adjuvant mechanisms of action
- sustained release of antigen at site of infection
- upregulation of cytokines and chemokines
- cellular recruitment at infection site
- increase antigen uptake and presentation to APC
- activation and maturation of APC (increased MHC class II and costimulatory molecules expression) and migration to draining lymph nodes
- activation of inflammasomes
example of adjuvant
alum - aluminium hydroxide
what happens when alum mixed with killed vaccine materials
Triggers NLRP3 inflammasome which turns on inflammatory markers = increase response
Local cytokine production
what are subunit vaccines made of
Consist of parts of organisms/products of organisms
effect after subunit vaccine
Immunisation doesn’t mimic natural infection but induces a response which prevents disease
what immunity is induced after subunit vaccine
usually only systemic immunity induced
how many doses are required following subunit vaccine
several
what is required in subunit vaccine
adjuvant
what are the ‘no risks’ of subunit vaccines
- no risk of infection
- no risk of reversion to virulence
- no unwanted components in vaccine
examples of subunit vaccines
tetanus toxoid
Hep B
Group C meningococcus
examples of subunit conjugate vaccines
meningococcal group C vaccine
what is the response to polysaccharide antigen conjugated to protein
(e.g. Dip toxoid or tetanus toxoid)
seeing polysaccharide not protein of the conjugate, gives T cell help, can get AB that are specific to polysaccharide
what is genetic shift
genetic reassortment
what does genetic shift cause
- pandemics
- cross-species mixing of virus genes
what is genetic drift
continuous mutational changes
what does genetic drift cause
- seasonal/epidemic
what is antigenic drift
neutralising AB against hemagglutinin block binding to cells –> mutations after epitopes in hemagglutinin so that neutralising AB no longer binds
what is antigenic shifr
antigenic shift occurs when RNA segments are exchanged between viral strains in secondary host –> no cross-protection immunity to virus expressing a novel hemagglutinin
all vaccines - contraindications to immunisation
- acute illness
- severe reaction to previous dose of same vaccine
live vaccines - contraindications to immunisation
- pregnancy
- primary immunodeficiency
- secondary immunodeficiency e.g. high dose steroids, cancer chemotherapy, HIV infection
allergic - contraindications to immunisation
Patient known to be allergic to vaccine/component
- influenza may contain traces of egg protein
- some viral vaccine contain traces of AB e.g. polymyxin or neomycin
what does poliovirus consist of
Poliovirus consists of RNA genome enclosed in protein shell capsid
how does poliovirus infect
oral-faecal route
what are the polioviruses that naturally occur
wild polioviruses
what are the serotypes of wild poliovirus
- type 1
- type 2
- type 3
how do the wild serotypes of poliovirus differ
slightly different capsid protein
what % of infected people with poliovirus not show symptoms
90
what is the route of infection for poliovirus
oral-faecal
- enters body via mouth
- replicated in intestine
- shed from body via faeces
what is iPV
inactivated polio vaccine
what is the problems with IPV
- relatively expensive
- little immunity in intestine
what is the benefits of IPV
extremely safe
what is OPV
live oral polio vaccine
what are the benefits of OPV
relatively cheap
good immunity in intestine – stop transmission
how is IPV administered
injection
how is OPV administered
orally
what are the problems with OPV
very safe, can revert to disease-causing form
what is OPV trivalent
protects against all 3 strains
what is OPV bivalent
protects against 1 and 3
what is OPV monovalent
protects against strain 1 or 3
which is the least effective OPV
trivalent
bivalent = 30% more effective than trivalent
and monovalent more effective than trivalent
