What is recombinant DNA vaccine? Give two examples.

Explanation

### Step-by-Step Text Solution:

1. **Definition of Recombinant DNA Vaccine**:
A recombinant DNA vaccine is a type of vaccine that uses genetically engineered DNA to produce an immune response. These vaccines are also known as nucleic acid vaccines. They involve the direct injection of plasmids containing DNA that encodes specific proteins from a pathogen (such as a virus or bacterium) into the host organism.

2. **Mechanism of Action**:
Once the DNA is injected into the muscle, the host's cells take up the plasmid DNA and begin to express the encoded protein. This protein is then recognized by the immune system as foreign, which stimulates an immune response. This response prepares the immune system to recognize and combat the actual pathogen if encountered in the future.

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