Wk 5 Vaccines Flashcards
What are 5 vaccine strategies?
- Live vaccines: cross-reactive, attenuated (whole pathogen)
- Inactivated (killed) vaccines w/ adjuvants (whole pathogen)
- Sub-unit vaccine (partial pathogen): toxoid vaccines; recombinant protein vaccines; polysaccharide vaccines; conjugate vaccines
- Vector vaccines: Adenovirus; Poxvirus
- Nucleic acid vaccines: DNA; RNA
What is a live vaccine?
Live organism efficiently stimulate innate and adaptive machinery. The best vaccines tend to be live. They also have the most adverse events.
Cross-reactive epitopes displayed by similar viruses (ie. cowpox and smallpox share some surface antigens, so immunization w/ cowpox induces Abs vs cowpox antigens, the Abs all bind and neutralize smallpox)
Example of live vaccine
Smallpox
Example of inactivated (killed) vaccine
polio
What is an inactivated (killed) vaccine?
Inactivated (killed) vs attenuated vaccines
What type of vaccines need to be avoided in immunodeficient?
Live (ex oral polio - why we use injected - less effective)
What is a subunit vaccine?
Anything that’s part of a pathogen, not all - usually a protein or polysaccharide
includes toxoid vaccines, recombinant, protein or polysaccharide
What is a toxoid vaccine?
Only express portion (inert protein part), not the toxic
-keeps toxin from interacting with host cells
-produces Abs against the toxin
-tetanus and diptheria
-HepB (HBsAg) vaccines induces neutralizing Abs that target surface antigens
What do polysaccharide sub-unit vaccines induce?
Marginal Zone B cells, which induces low affinity IgM - short-lived, migrate to inflammed tissues
-pneumococcus and meningococcus (both diplococci) (short-lived, 1-3 years)
What is special about polysaccharide-specific B cells?
Live in the marginal zone of the spleen
Specialized for T-independent Ab responses
* No isotype switching: IgM only
* No affinity maturation
* No memory
* Many non-protein antigens that T cells can’t respond to
Example of sub-unit vaccine?
Hep B
What are conjugate vaccines?
Goal - produce long-lived IgG responses to polysaccharides
What are conjugate vaccines?
Goal - produce long-lived IgG responses to polysaccharides
How does conjugate work?
Conjugate polysaccharide and conjugate it to carrier protein
B cell has something to present on MHC Class II to T cells -> long-lived high affinity IgG
What is meningococcal vaccine for?
polysaccharide vaccine that targets the 4 (of 6) main serotypes
What are vector and nucleic acid vaccines?
SARS CoV-2
Vector vaccine
Take replicating, live adenovirus, add protein you want to immunize against
mRNA vaccines
Good for boosting secondary responses
DNA vaccines
Hope bead will puncture a cell and induce RNA production
What is an ajuvant?
Live viruses induce stronger inflammatory responses.
We want vaccines to produce bigger response w/o being live
Adjuvants produce macrophage activation, recruitment of inflammatory cells, cytokine production, prolonged inflammation (depot effect of oil-in-water emulsions)
