Third generation vaccines are:

Options

A. Attenuated pathogen
B. Pathogen relative
C. Monoclonal antigen
D. Synthetic antigen

Answer

**Step-by-Step Solution:**

1. **Understanding Vaccines**: Vaccines are biological preparations that provide immunity against a specific disease. They contain an agent that resembles a disease-causing microorganism and is often made from weakened or killed forms of the microbe, its toxins, or one of its surface proteins.

2. **Classification of Vaccines**: Vaccines can be classified into different generations based on their composition and how they stimulate the immune response. The three main generations are:
- **First Generation Vaccines**: These include whole pathogens that are either killed or attenuated (weakened). Examples include the BCG vaccine for tuberculosis.
- **Second Generation Vaccines**: These vaccines use parts of the pathogen, such as proteins or polysaccharides, to elicit an immune response. An example is the hepatitis B vaccine, which uses a portion of the virus.
- **Third Generation Vaccines**: These are more advanced and utilize synthetic methods to create vaccines. They often involve recombinant DNA technology to produce antigens that can elicit an immune response without using the live pathogen.

3. **Identifying Third Generation Vaccines**: Third generation vaccines are characterized by:
- The use of synthetic antigens that are man-made.
- The incorporation of genetic material from the pathogen using recombinant DNA technology.
- The use of plasmids to deliver the genetic material into the body, prompting an immune response.

4. **Examples of Third Generation Vaccines**: These vaccines are designed to be safer and more effective by using engineered components that specifically target the immune system without the risks associated with live pathogens.

**Conclusion**: Third generation vaccines are synthetic vaccines that utilize recombinant DNA technology to produce antigens that stimulate an immune response without using live pathogens.

---