Recombinant Vaccines Question Flashcards
6 topics to discuss
Live attenuated
Recombinant subunit
Virus vector
DNA
Edible plant based
mRNA
Live attenuated example
Polio
Live attenuated
Weaker form of vaccine through multiple passaging at progressively lower temp
Administered mucosally typically
Mimic natural infection -> long lasting immunity
-reversion
- disease in immunocompromised host
- manufacturing and storage required stringent conditions
Live attenuated RSV
Cold adapted temperature strategy
Could not find balance between immunogenicity and pathogenicity in infants. Alternative strategy was to remove virulence factors. Research ongoing
Recombinant subunit vaccines example
Hep B and HPV
Recombinant subunit vaccines development
Identify potential antigens
First in silico B and T cell epiptope candidate identification
Pep scan for T cell proliferation
ELISA for antibody reactivity
Recombinant subunit advantages
High safety as do not contain live or inactivated virus
Well defined, highly purified
Targeted immune response against specific antigen
How do we combat massive strain variation in HIV?
Recombinant vaccine derived from multiple strains or perhaps identify an antigen that confers subtypic immunity
Recombinant vaccine disadvantages
May require adjuvants; very little choice of adjuvants; major research underway
Some viral antigens have complex structures that are challenging to produce recombinantly
Multiple doses may be required
Massive strain variation in HIV
What happened this week?
AREXVY 🥳🥳🥳🥳
83% efficacy
An example of a virus vector
SeV
Virus vector
Engineered viruses that can deliver viral vaccines into host cells
Advantages of virus vector vaccines
Efficient delivery and expression of viral antigen => mimicking natural infection
Induce cellular and humoral immune responses
Can target specific cells or tissues
Disadvantages of virus vector vaccines
Pre existing immunity to vector may limit immune response
The immune response to the vector can limit subsequent vaccination
Vector production and purification is costly and time consuming
DNA vaccines development
Direct introduction of plasmid DNA encoding viral vaccine antigens into host cells. Host cells produce viral antigen => immune response
DNA vaccine advantages
Simplicity in design manufacture and storage
Still in development
Can induce both humoral and cellular immune response
Rapid development and scalability
DNA vaccine disadvantages
May require delivery systems and or adjuvants
Further research into safety is needed
Edible plant based vaccines development
Expression of viral antigens in GMO plants which can be consumed e.g tomatoes
Edible vaccines advantages
Ease of production
Scalability
Cost-effective
Eliminate need for injections
Natural exposure and mucosal immunity
Edible vaccine disadvantages
Regulatory hurdles and public perceptions on GMO
Achieving high antigen expression levels is difficult and hard to maintain their stability
More work needed on efficacy and safety
mRNA development
SARS-CoV-2
25 years into mRNA vaccines, 10 years into SARS/MERS spike protein research
Utilises mRNA encoding viral vaccine antigen, taken up by host cells, transcribed and triggers immune response
mRNA vaccine advantages
If sequence is known vaccine can be developed easily and efficiently
Strong immune response
92% efficacy
mRNA vaccine disadvantages
Labile
Needs delivery package e.g lipids
Must be stored at extremely low temps
