ELISA is a technique used for early diagnosis of pathogen and is based on

Options

A. using radio labelled second antibody
B. detecting the RBCs
C. complement-mediated cell lysis
D. detecting the antibodies synthesized against the pathogen

Answer

**Step-by-Step Solution:**

1. **Understanding ELISA**: ELISA stands for Enzyme-Linked Immunosorbent Assay. It is a laboratory technique used to detect and quantify proteins, typically antibodies, in a sample.

**Hint**: Remember the full form of ELISA and its purpose in diagnostics.

2. **Principle of ELISA**: The technique is based on the specific binding of antibodies to antigens. When a pathogen enters the body, the immune system produces antibodies that specifically target that pathogen.

**Hint**: Focus on the interaction between antibodies and antigens as the core principle of ELISA.

3. **Procedure**: In a typical ELISA setup, antigens are coated on a plate. When a sample containing antibodies is added, these antibodies bind to the antigens. A secondary enzyme-linked antibody is then added, which binds to the primary antibodies.

**Hint**: Visualize the step-by-step binding process: antigen → antibody → enzyme-linked antibody.

4. **Detection**: The presence of the enzyme linked to the secondary antibody can be detected through a color change or fluorescence when a substrate is added. This indicates the amount of antibodies present, which correlates with the immune response to the pathogen.

**Hint**: Think about how the enzyme activity leads to a measurable signal that indicates the presence of antibodies.

5. **Conclusion**: ELISA is primarily used to detect the antibodies synthesized against pathogens in the body, which is crucial for early diagnosis of infections.

**Hint**: Remember that the detection of antibodies is key to diagnosing infections early.

**Final Answer**: ELISA is based on detecting the antibodies synthesized against the pathogen.

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