ELISA which is a molecular diagnosis technique is based on the which principle?

Answer

**Step-by-Step Solution:**

1. **Understanding ELISA**: ELISA stands for Enzyme-Linked Immunosorbent Assay. It is a widely used laboratory technique for detecting and quantifying proteins, antibodies, hormones, and antigens.

2. **Principle of ELISA**: The fundamental principle behind ELISA is the interaction between antigens and antibodies. This interaction is crucial for the detection of various diseases, including viral infections like HIV.

3. **Antigen-Antibody Interaction**: In the context of ELISA, the test can either detect:
- **Antigens**: These are substances that provoke an immune response, typically found on the surface of pathogens (like viruses or bacteria).
- **Antibodies**: These are produced by the immune system in response to the presence of antigens. They can be detected in a patient's serum.

4. **Application in Diagnosis**: When a pathogen infects the body, it introduces antigens that can be detected by the ELISA test. Alternatively, if the body has produced antibodies against the pathogen, those can also be detected. The presence of either indicates an infection.

5. **Conclusion**: Therefore, the ELISA technique is fundamentally based on the principle of antigen-antibody interaction, which allows for the detection of infectious diseases.

**Final Answer**: ELISA is based on the principle of antigen-antibody interaction.

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