Vaccination Flashcards
(12 cards)
Passive vaccination
Human hyperimmune serum to give IgG from donor with high titre of antibodies to a particular pathogen to then pool in plasma against common infections. Immediately active and immediate effect (hence useful for post-exposure prophylaxis).Eg for rabies and Hep B. But short lasting and can cause serum sickness due to presence of foreign protein.
Active vaccination
Requires injection of inactive or parts of pathogen, provides long duration immunity with an effective and appropriate immune response.
Benefits of active vaccination
Provides information about contribution of a pathogen to a particular disease. Hope that it can be inexpensive, stable, easy to administer and provide good herd immunity. (But this is not always the case)
Live attenuated vaccine
Will multiply inside host and provide strong antigenic stimulation, via cell mediated immunity. May possibly revert to virulence (as able to continue mutating) so cannot give to anyone immunocompromised or pregnant. Eg measles vaccine or Sabin polio virus.
Killed whole microorganism vaccine
Does not multiply in human hosts but still provokes reaction due to MAMPs or PAMPs, tends to require multiple doses with boosters. Less cell-mediated immunity but no possibility of vaccine related infection.
Microbial components
Can give subunit components associated with virulence, targeting particular pathogen functions - eg attachment (fimbriae, pertactin), toxins.
Toxoids
Acellular vaccine giving only exotoxins which have been rendered non-toxic by chemical treatment. Eg tetanus bacterium produces a toxin that can be modified by formalin treatment so it retains epitopes but loses its toxicity.
Conjugate vaccines
Covalent binding of antigenic polysaccharide to a protein causes higher immune antibody production response than unconjugated polysaccharide. Conjugate fiven for pneumoccocus as there are many common capsules. 13 valent used.
Serotype replacement
Exclusion of bacteria susceptible to one vaccine will then be replaced by other organism. Hence meningitis ACWY variants.
Flu vaccine
Vaccine targets haemagglutinin and neuraminidase proteins, inactivated is highly strain specific and induces antibody immunity, live also induces cell immunity. Fairly safe as grown in embryonated chicken eggs and then replicates poorly in human cells.
First vaccine against viruses
Hilleman 1981 used purified hepatitis B surface antigen (HBsAg). Remains very effective vaccine.
HPV vaccine development
HPV major capsid protein L1 is produced by gene cloning and expression in yeast cells. L1 spontaneously assembles into virus-like particles which are highly immunogenic but contain no viral genetic information. Attempt to combine L1 serotype into a single shot. Potential to prevent many tumours.
