Chapter 18 Vaccines. Termed coined by Pasteur to honor Jenner’s work Vaccines are cost-effective uses of our immune system Dramatic reduction of Diptheria Measles Mumps Pertussis Polio Tetanus No more naturally acquired cases of smallpox!. Still a significant need for new vaccines.
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If Antibody is produced in another spp, the human recipient can produce an IR vs it…
In some IgE production vs isotypic Ab -> systemic mast cell degran -> anaphylaxis
In others IgM or IgG vs isotype -> complement activation -> Type III Rxn
If human gammaglobulin results can be less severe
*children require booster shots for most…
(American Academy of Pediatrics, 2002)
Important questions to consider:
1- Which IS should be activated?
2- Is immunologic memory stimulated?
This depends on the disease..
Influenza has a short incubation (1-2 d) effective imm vs flu depends on maintaining hi levels of Ig through repeat immunizations
Polio virus has a longer incubation (>3d) gives memory cells time to produce serum Ig
-can still grow to a degree w/i inoc. host
Provides prolonged IS exposure to epitopes
> immunogenicity, > memory
Typically req. ONLY 1 shot
Stimulates host cell-mediated response
Poss. of reversion to virulent form and side effects
Ex: Polio and Measles
-can be performed with heat or chemicals*
(formaldehyde, alkylating agents)
Avoids the risks of the ‘whole org’ vaccines
-3 forms: inactivated exotoxin
recombinant MO antigens
-purify exotoxin, treat with formaldehyde
-produces anti-toxin Ig which bind to toxin
-exotoxin genes can be cloned/recombined in cells to produce large quantities
**used for diptheria and tetanus
2) Capsular polysaccharides-
-Vaccines using capsular components stim Ig prod
-Vaccines for Strep pneu, N. meningitidis -> purified polysacch injected subcutaneously to activate memory B cells and IgA response!
Can invoke Th activation if polysacch is added to protein carrier (Ex: Hib is cap polysacch linked to tetanus toxoid)
3) Recombinant MO Antigens –
HepB surface Ag (HBsAg) – cloned in yeast
-may be able to produce large amts of vaccine this way!
-hope for 250 million+ carriers of chronic HepB worldwide
-Genes encoding significant Ag’s from pathogens may be transferred to attenuated viruses/bacteria
Vectors include: vaccinia, polio, adenoviruses
Salmonella, BCG strain of M. bovis, oral Strep
Other vectors may prove to be safer