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Questions and Answers
What role do antigens play in the immune response?
What role do antigens play in the immune response?
Antigens are foreign substances that stimulate an immune response.
What is the purpose of a secondary antibody in the ELISA test?
What is the purpose of a secondary antibody in the ELISA test?
The secondary antibody recognizes the first antibody and is crucial for the detection process.
In the context of ELISA, what is the significance of washing steps?
In the context of ELISA, what is the significance of washing steps?
Washing steps remove non-bound reagents and interfere with test accuracy.
How does a color change using tetrazolium dye indicate bacterial growth?
How does a color change using tetrazolium dye indicate bacterial growth?
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What does a positive control group indicate in immunological testing?
What does a positive control group indicate in immunological testing?
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Why is PBS used in ELISA procedures?
Why is PBS used in ELISA procedures?
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What could result from inoculating too many bacteria in the Biolog System?
What could result from inoculating too many bacteria in the Biolog System?
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What does the turbidity measurement indicate in a bacterial assay?
What does the turbidity measurement indicate in a bacterial assay?
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How does colorimetric detection work in the ELISA test?
How does colorimetric detection work in the ELISA test?
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What is the incubation temperature for the Biolog System, and why is it important?
What is the incubation temperature for the Biolog System, and why is it important?
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Study Notes
ELISA Test
- Antigens are foreign substances that trigger an immune response.
- Antibodies are proteins produced to neutralize antigens.
- ELISA (enzyme-linked immunosorbent assay) is used to detect antigens and antibodies.
- Used to diagnose infections—HIV, EBV, and others.
- Basis of pregnancy tests, drug screenings, and food allergy detection.
- Secondary antibody recognizes the first antibody.
- Colorimetric detection—color change indicates the presence of serum antibodies (exposure to a pathogen).
- Infectious mononucleosis (kissing disease) is transmitted via saliva.
- Epstein-Barr Virus (EBV) is linked to chronic fatigue syndrome.
- Washing steps remove unbound reagents, ensuring accurate results.
- Positive control indicates a positive result (antibodies added).
- Negative control shows a negative result (no color change—no antibodies).
- Enzyme is conjugated to the secondary antibody for color detection.
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Procedure:
- Label wells.
- Add viral antigens to all wells.
- Incubate (5 minutes, room temperature).
- Remove liquid & wash with phosphate-buffered saline (PBS).
- Add test reagent & incubate (37°C).
- Remove/rinse.
- Add secondary antibody and incubate (15 minutes, 37°C).
- Rinse twice with PBS.
- Add substrate, incubate, and observe color changes for positive results.
Biolog System
- Biolog system identifies bacteria based on metabolic properties.
- Identifies Gram-positive and Gram-negative species.
- 96-well plate is used.
- Carbon sources (sugars, amino acids, carboxylic acids).
- Sensitivity tests (antibiotics, salt, acidic pH).
- Positive results: tetrazolium dye reduction (purple color).
- Tetrazolium is a redox dye.
- Incubation at 33°C until reduced color.
- Turbidimeter measures light transmittance to determine bacterial concentration.
- Transmittance—percentage of light passing through the sample.
- Negative controls help detect biases.
- Overinoculation can lead to cross-contamination, affecting accuracy.
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Procedure:
- Unwrap and label the microplate.
- Obtain a bacteria sample from an agar plate.
- Transfer bacteria to inoculating fluid; create a suspension.
- Thoroughly mix.
- Use a turbidimeter to determine transmittance.
- Transfer the entire suspension to the reservoir.
- Transfer to the microplate's wells (96 wells).
- Incubate at 33°C.
- Observe color development (3-36 hours).
- Read results.
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Description
This quiz explores the ELISA test, a vital method used to detect antigens and antibodies in diagnostic procedures. It covers its applications in diagnosing infections like HIV and EBV, the role of antibodies, and specific detection methods such as colorimetric detection. Additionally, it highlights the importance of controls in ensuring accurate results.
