How is a vaccine produced by recombinant DNA technology? Give an example and its advantages.

How to lay out the answer. Follow the frame, then write it in your own words.

1 · Define in one line. A recombinant vaccine contains a pathogen's antigen made in bacteria or yeast from its cloned gene.
2 · Clone the gene. The gene for a surface antigen is joined to a vector and put into yeast.
3 · Produce and purify. The yeast is grown in bioreactors; the antigen is purified and formulated.
4 · Give the example. The hepatitis B vaccine is made this way.
5 · State the advantages.
- Cannot cause the disease.
- Made in large amounts, so widely available.
6 · Link to real life. Indian newborns receive this hepatitis B vaccine under the immunisation schedule.
7 · Close in one line. So rDNA technology gives safe vaccines on a large scale.

Scoring tip: Name the antigen (surface protein), the host (yeast) and the example (hepatitis B).