Med Micro 8 - Vaccines Flashcards
What is a vaccine?
suspension of attenuated or killed microorganisms, or of antigenic proteins derived from them, administered for prevention, amelioration, or treatment of infectious diseases
Types of vaccines
Attenuated (live - attenuated virulence), Killed (inactivated and avirulent), Toxoid (inactivated and avirulent), Others (nucleotide, conjugate, Viral like particle)
Attenuated
Weakened so they cannot cause disease. Stripped of essential virulence factors, heat killed, etc.
What type of vaccine would you use to generate as large an immune response as possible? What cell would you target? How?
It is an open question. One way: target APC with attenuated vaccine. It stimulates release of cytokines, chemokines, interleukin, GF, so antigens will be presented to T helper cells to activate adaptive immune response. Polyclonal response
What would you do if you couldn’t produce an attenuated vaccine to generate as large an immune response as possible? What cell would you target? How?
It is an open question. One answer: Target a Pro APC using a PAMP with a linked specific antigen (conjugated vaccine). Stimulates the immune response.
Changing face of vaccine development
Conventional development and reverse vaccinology
Conventional vaccine development
take some pieces of a pathogen (ie flagella, cell surface), test in convalescent sera, test immunogenicity (agglutination), purify, identify, clone genes, test in animal models. 10-15 years
Reverse vaccinology
aka reverse genetics. Based on DNA, identify potential candidates based on homology and function (computer prediction). Way faster.
Convalescent sera
Serum from someone recovering from a disease. They have Ab so you can test.
Why is ELISA so important?
Test for Ab binding an antigen. If people have the Ab, they’ve been exposed to the antigen
Use of LD50?
Not so good to identify pathogen etc; Tell you whether or not vaccine candidate is protective
Hydropathy plots
help us know where in membrane. Can focus on one place and make conjugated vaccines.
Process of attenuation for virus (classic)
Isolate virus from infected human and grown in human tissue culture; grow in tissue culture of another species; virus gains mutations to grow there, but no longer can infect humans
Process of attenuation for bacteria (classic)
Culture under weird conditions or genetic manipulation
Attenuated vaccine - reverse genetics method
Insert genes from a virulent strain into a the coat of a non-virulent strain ***
What is a potential concern with vaccines even if they are avirulent? Why?
May generate an allergic reaction (rare) or inflammatory response,
Killed/Inactivated Vaccine
Deactivated whole microbes or subunit. When killing we need to maintain antigen structure. Formaldehyde - causes cross-linking of proteins and nucleic acids
Adjuvants
Goal is to stimulate an immune response. Ex. slow down processing of antigen so immune response has more time to be activated
Elements of gene
Start site (Met), stop site, promoter (RNA polymerase binding), transcriptional start and stop, translational start and stop (not same as transcript), regulatory sequences (operator - b/w promoter and start, used to stop RNA poly). Genes produce polypeptide.
Do all genes have a promoter?
No, operons are several genes but have only one promoter
How do we express a gene outside of its normal host?
Plasmid in E. coli for example.
How do we express the protective parts of a gene?
Cut out parts that will be exposed on outside, then link the piece to other pieces or something else. Need a promoter
How can we define what parts of a gene would be protective?
Something that is exposed that the immune system would recognize if there was an infection, so we can protect ourselves against it. Hydropathy plots.
If protective parts are too small to make a immune response what do you do?
Make conjugate vaccines! Lots of
