New Vaccine Development Flashcards
(41 cards)
What are the criteria of a good vaccine?
Safe, effective
Delivery method and vaccination schedule
Affordable and quick to make
Easy to store and transport
What is empiricism?
Knowledge obtained by direct or indirect observation or experience
What is rational design?
Creating new molecules with certain functionality - custom made
What are the components of vaccine formulation?
Antigens
Adjuvants
Delivery systems
What are the types of antigens for vaccines?
Live
Attenuated/inactivated
Subunit
VLPs
Glycoconjugate
DNA/mRNA vaccine
What do adjuvants do?
Help to generate strong, long-lasting protective immune response
The combat low immune response to non-living vaccines and have oral tolerance
What are advantages of adjuvants?
Dose sparing
More rapid immune response
Antibody response broadening
What are the types of adjuvants?
Empirical - alum
Immunostimulants - interact with specific receptors
Delivery systems can also be adjuvating
What are the types of immunostimulants?
TLR agonists - PAMPs, e.g. MPL, CpG DNA
Derivatives of bacterial enterotoxins - e.g. cholera toxin subunit B (CTB); used in mucosal vaccines to recruit e.g. M cells
Cytokines and chemokines - e.g. IL-12
What are methods for needle-free immunisation?
Electroporation
Microneedles
Oral vaccines
Chemical nanoparticles
Give some examples of chemical nanoparticles
Liposomes - act as carriers
Immune stimulating complexes - act as carriers and adjuvants
Nanogels - act as carriers and adjuvants
Nanoemulsion - act as immunostimulants
They can act as vaccine carriers or delivery vehicles or can be immunostimulants themselves
What is used for delivery of DNA vaccines?
Viral vectors
What do DNA and mRNA vaccines activate?
Cellular and humoral responses
What is the function of the viral envelope for DNA vaccines?
The protective layer of the viral envelope has the capability of delivering DNA to the host cells like a normal virus and inducing an immune response
Must be heavily modified to remove infectious components of the virus as the viral vectors are live attenuated viruses
How are viral vectors made safe?
Host-restricted - will not replicate itself within the tissues of a host e.g. Oxford/AstraZeneca SARS-CoV-2 vaccine
Self-replicating, attenuated - will not shed from host e.g. Ebola vaccine
How can the safety of viral vectors be increased?
Continuous passaging e.g. modified vaccine ankara
Non-selective in types of viral genes lost or altered
Packaging constructs and cell lines
Pseudotyping for modified efficiency and cell tropism
How are viral vectors made using packing constructs?
Put what you want to pack inside the viral envelope between the encapsidation signal - for example, can be genes of a DNA vaccine for the viral vector to deliver
Packaging construct codes for the genes of the viral envelope and do not have encapsidation signals
When both genes inserted, mammalian cells will make more of the encapsidated DNA but do not translate them into proteins
Genes that are not encapsidated are translated into structural proteins of the viral vector
Structural proteins and encapsidated DNA vaccine genes combined together in mammalian cells and viral vector can be purified out
How are live attenuated vaccines made in the empirical era?
Sample of the pathogen obtained (seed virus)
Inoculate seed virus sample into production platform e.g. mammalian cells more recently being used
Virus will replicate in production platform
Virus purified
Chemicals used to inactivate the virus before formulating in a vaccine for further testing
How are protein-based vaccines made?
Take DNA from protein of interest
Promoters and terminators that flank the gene of interest need to be related to the organism we want the protein to be produced in i.e. for mammalian cell platforms, mammalian promoters and terminators are used
DNA plasmid can be introduced into the manufacturing platform (plant, bacteria, mammalian) by chemical means or by viral vectors or by bacteria that naturally infect plants
In host platforms, there is already machinery in place to transcribe the DNA and translate them into recombinant proteins that can then be purified and used as a vaccine
How are DNA/RNA vaccines made?
Similar to protein vaccines however the difference is that the vaccinees are the manufacturing platforms - they make the proteins themselves
How is the SARS-CoV-2 DNA vaccine made?
Spike protein has all the criteria to generate a good immune response so this was chosen as the vaccine antigen
To generate DNA vaccine, the DNA coding for the spike protein is inserted into a plasmid which can be injected into the patient directly
Otherwise can be packaged into a viral vector
How is the SARS-CoV-2 RNA vaccine made?
mRNA from spike protein obtained
For RNA vaccines, some form of packaging will be needed to protect the more fragile mRNA and deliver it to the cell - nanoparticle usually used is a form of lipid bilayer that engulfs millions of copies of mRNA coding for the spike protein in its cavity
The whole thing is then injected into the patient and the patient’s cells will use the mRNA to make the spike protein to trigger an immune response
How do DNA and mRNA vaccines work?
Have the DNA/RNA coding for the spike protein protected by viral vector (DNA) or nanoparticle (mRNA)
When injected into cells of vaccinee, the DNA/mRNA uncoats and cells recognise this and make the spike proteins
These proteins trigger an immune response that produce antibodies that neutralise the spike protein
What are some rational design strategies?
Synthetic vaccine
Reverse vaccinology
Structural vaccinology
pDNA or mRNA vaccine