VPB 321: Animal Biotechnology (2+1)

RECOMBINANT DNA VACCINE

• Recombinant DNA technology, in which a section of DNA from one species is inserted into the DNA of another, is proving to be useful in the manufacture of vaccines that contain only the desired antigen - usually one or several proteins - without the need for attenuated toxins or modified versions of the disease causing virus or bacterium. This results in the production of an immune response without the risk of actual contraction of the original disease, and is potentially more cost effective and commercially viable.
• An example of how the recombinant vaccine process works can be seen in the production of Tickgard vaccine. Here, genes responsible for the manufacture of the gut protein Bm86 in the cattle tick, Rhipicephalus microplus, are inserted into the plasmid DNA and then transformed into the E.coli. These microbes are cultured, and express the Bm86 protein on a large scale. The protein can then be purified and injected into cattle, with the result that their immune system will protect them against the Bm86 antigen introduced in a real tick bite.
• Current research has found that, although the Bm86 gene can be adequately expressed in recombinant E. coli bacteria and strains of the fungus Aspergillus, the yeast, Pichia pastoris has proved to be the most successful at secreting the protein. One reason for this is its rapid growth rate and its ability to grow on inexpensive media.