Biotechnology and Bioinformatics (1+1)

4.3.12. Subunit vaccines

Subunit vaccines are produced by genetic engineering . They are purified single proteins from the surface of a pathogen which can be produced cheaply in fermenters.

The great advantage of subunit vaccines is that they contain no live, potentially infectious organisms. The subunits are advantageous because the immune system of the animal is challenged with only one antigen, thereby omitting other components of the virion that might adversely affect the immune response.

The major drawback with subunit vaccine is that the antigenic mass cannot be greater than the amount injected. There is no amplification of the antigen. The first step in the production of recombinant subunit vaccine is the isolation of immunogenic genes, which are amplified by cloning .

The specific genes of virions are purified from the preparation of DNA or cDNA in case of RNA viruses. The DNA is amplified by cloning and cleaved with restriction endonuclease s to small fragments.

The DNA fragments which code for immunogenic proteins are identified and used for the preparation of recombinant vaccines.