TRADITIONAL PLATFORMS VS NEXT GENERATION PLATFORMS
The vast majority of vaccines currently licensed for human use are Traditional Platforms which should be distinguished from Next Generation Platforms*.
1) virus-based -
a) inactivated virus that is no longer infectious,
b) or live-attenuated virus.
Live-attenuated virus vaccines are traditionally generated by passaging in cell culture until it loses its pathogenic properties and causes only a mild infection upon injection.
a) consist of a protein purified from the virus
b) virus-infected cells,
c) recombinant protein
d) virus-like particles
**Protein-based vaccines require the addition of an adjuvant to induce a strong immune response. Two COVID-19 vaccines based on these traditional platforms are currently in clinical trials, one based on whole-inactivated virus and one consisting of recombinant protein.
Next Generation Platforms:
For COVID-19, several viral vector, nucleic acid-based biologics and antigen-presenting cells are in (pre)clinical development .
1) Viral vector biologics
Viral vectors result in endogenous antigen production, both humoral and cellular immune responses are stimulated.
a) recombinant virus (that is, the viral vector), often attenuated to reduce its pathogenicity, in which genes encoding viral antigen(s) have been cloned using recombinant DNA techniques.
Replicating vectors infect cells in which the antigen is produced as well as more infectious viral vectors able to infect new cells that will then also produce the antigen.
Non-replicating vectors initially enter cells and produce antigens, but no new virus particles are formed.
2) Nucleic acid biologics (NABs)
Genetic vaccines consist of DNA or RNA,which is taken up and translated into protein by host cells. NAVs employ the host’s transcriptional and translational machinery to produce the desired gene product.
3) Antigen-presenting cells
made of antigens and antigen-presenting cells (APCs).
*Definitions, characteristics and functions of Next Generation Platforms on this site are under development