Developing recombinant DNA vaccines Flashcards
1st generation vaccines
Entire attenuated pathogen included
E.g. polio, MMR, influenza, hep A and small pox
Limitations of first gen vaccines
Attenuation reversal
Attenuation may destroy epitopes in process
Can’t use against rapidly evolving pathogens
Benefits of first generation vaccines
No risk of autoimmunity
Second gen vaccines
Reverse vaccinology sequences genome of pathogen
Desired gene is inserted into organism that can be cultured in lab - e.coli
No risk of attenuation reversal
Pros of bacterial systems
Easy, quick, economical, continuous rapid production
Negatives of bacterial systems
Can’t remove introns, foreign gene might cause premature termination
Accumulation of toxins
Positives of yeast system
Rapid growth, post-translational modifications, no endotoxin production
Negatives of yeast system
Hyperglycosylation of proteins
Intracellular retention of proteins from DNA
Positives of using insect system
- High levels of protein expression
- Posttranslational modifications
- Insect viruses - safe for vertebrates
- Good for recombinant glycoprotein production
Drawbacks to using insect system
- Virus will eventually kill cell
- Specific culture conditions
Positives of mammalian cell system
- Proper folding
- Post-translational modifications and assembly
Drawbacks to mammalian cell system
- High cost
- Complicated
- Contamination with animal viruses
Positives of transgenic plant
- Easy scaling up at low cost
- Proteins localised to different organs
- High yield
- Post-translational processing
- Vegan
drawbacks to using transgenic plants
- Expression levels target dependent
- Functional assays yet to be developed
Function. of adjuvants
Stimulate innate immune response
Why are aluminium adjuvants used?
Increase antibody production
Third generation vaccines
- DNA vaccine: injection of naked DNA plasmid into muscle tissues in host - antigen is expressed directly by cells of host (viral infection). Antigens processed as proteins and fragments of peptides presented by MHC. If protein secreted, can be processed by MHC ii = non-specific AB immune response
- DNA encapsulation/live vector use protects delivery of DNA into host cells
