principles of immunisation Flashcards
what two types of immunity are there?
acquired
innate
what two forms of acquired immunity are there?
active
passive
what two types of active and passive immunisation are there?
natural and artificial
how long does active immunity last for?
long term, may be lifelong
does active immunity display immunological memory?
yes
how quickly does active immunisation take effect?
no immediate effect, but faster and better response to next antigen encounter
what is the first antibody that is developed in an immunological response?
IgM
what antibody is present in large quantities during the second exposure to a pathogen that someone has been immunised against?
IgG
How do live attenuated vaccines work?
live form of the pathogen that has been attenuated is given
what are the risks of live attenuated vaccines?
reversion to the fully pathogenic organism may occur
how is the pathogenic organism attenuated in a live attenuated vaccine?
repeated passage in a cell culture or non human host
when would a live attenuated vaccine be unsuitable to prescribe?
if a patient is immunocompromised or pregnant
what are some examples of live attenuated vaccines?
MMR, BCG, Polio, varicella zoster
how is a pathogen inactivated in a killed vaccine?
usually chemically inactivated using formaldehyde
how does the immune response of a killed vaccine compare to that of a live vaccine?
weaker immune response - multiple doses may be required
what do some killed vaccines contain that increases the immune response?
adjuvants
what is a toxoid vaccine?
vaccine where toxin is treated with formalin, so the toxoid retains antigenicity but not toxicity
what are some possible side effects of killed vaccines?
can produce inflammatory responses against other proteins and antigens contained within the vaccine
what does a toxoid produce immunity against?
the toxin itself, not the organism that produces it
what are some advantages of subunit vaccines?
no infectious agent, highly purified
easy to produce in large amunts
what are some disadvantages of subunit vaccines?
increasing purity of the vaccine leads to a loss of immunogenicity - may need adjuvant
what 2 types of subunit vaccines are there?
purified microbial products
recombinant (genetically engineered)
how can a recombinant subunit vaccine be made?
gene encoding antigen is excised from the organisms nucleic acid
gene is inserted into yeast chromosome by molecular genetic techinques
yeast grows in culture and produces antigen
what is a conjugate vaccine?
vaccine where the original antigen is a carbohydrate capsule which then is conjugated to a protein carrier to make it more effective
what are the steps of herd immunity?
primary aim of vaccination is to protect the individual who receives the vaccination
vaccinated individuals are less likely to be a source of infection to others
reduces the risk of unvaccinated individuals being exposed to infection
individuals who cannot be vaccinated still benefit from routine vaccination programmes
how does immunising a pregnant woman against a pathogen protect the baby?
antibodies are transferred through the placenta so the baby has some form of immunity when it is born
what are some contraindications of vaccination?
temporary - febrile illness, preganant woen cannot be given live attenuated vaccines
permanent - allergy, and immunicompromised patients cannot be given live attenuated vaccines?
what are some natural forms of passive immunity?
placental transfer of IgG
colostral transfer of IgA
what are some artificial forms of passive immunity?
treatment with immunoglobulin
immune cells
what is the difference between human normal immunoglobulin and human specific immunoglobulin?
human normal immunoglobulin contains all antibodies
human specific immunoglobulin is taken from selected blood donors with high antibody titres against a specific organism
for what pathogens would you give prophylactic human normal immunoglobulin?
hep A
measles
polio
rubella
for what pathogens would you give prophylactic human specific immunoglobulin?
hep B
rabies
tetanus
varicella zoster virus
what are the advantages of passive immunity?
immediate protection
what are the disadvantages of passive immunity?
hshort term effect - no immunological memort
serum sickness - antibody can be recognised as a foreign antigen by the recipient which can result in anaphylaxis
graft versus host disease ( cell grafts only) incoming immune cells reject the recipient
