What are DNA vaccines ?

Explanation

**Step-by-Step Solution:**

1. **Definition of DNA Vaccines**: DNA vaccines are a type of vaccine that uses a small, circular piece of bacterial DNA known as plasmids to induce an immune response in the body. They are classified as third-generation vaccines.

2. **Composition**: DNA vaccines are composed of plasmids that have been genetically engineered. These plasmids contain the desired gene that codes for a specific antigen related to a pathogen.

3. **Genetic Engineering Process**: The process involves cleaving the plasmid using restriction enzymes to insert the desired gene. This results in a recombinant plasmid that now carries the gene for the antigen.

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