lecture 16 Flashcards
how are live-attenuated vaccines made?
the pathogen is passaged lots of times under stress conditions, pressuring the virus to replicate differently, with slower replication and loss of virulence factors as the result. this process makes the virus attenuated( no longer disease causing), then the virus is purified and formulated. (there is an expample on slide 5)
how are inactivated vaccines are made
the whole pathogen is grown and killed by heat and/or chemical modification (fomarldehyde). the examples are Pertussis, cholera.
IPV (Inactivated Polio), Influenza, Hepatitis A.
Advantage
Relatively easy
Generally safe to administer - no risk of reversion, infection.
how are recombinant sub unit vaccines are made
we first identify the gene for the sub unit being targeted then insert it into a host-organism for production. this expresses protective antigen in a safe, easy to grow environment. examples are Hepatitis B (HBsAg expressed in yeast)
HPV (papilloma L1 expressed in yeast)
lastly, we purify the antigenic sub unit and formulate
how are toxoid vaccines made
the toxins from pathogens are isolated and purified and they are converted to toxoids (inactivated toxin) by chemical treatment. the Toxoid is then formulated
what is the target of conjugate polysaccharide vaccine and how are they made
they typically target childhood diseases. there typically are two phases in the production of conjugate vaccines. firstly the Surface polysaccharide from the pathogen is grown up (fermentation) and isolated.
The carrier protein is grown up separately (usually in E. coli) and purified. then any toxins on the polysaccharide are removed (chemically).
The carrier protein and the polysaccharide are then covalently attached together (chemical crosslinking).
The ‘conjugate’ is then purified and formulated.
heamophilus influenze type B example
slide 11 and 12
why do we need adjuvants
adjuvants enhance the protection provided by vaccines by promoting rapid, long-lasting and broad immunity
answer in slide 15
