IB Biology Practical Investigations/Human Health and Physiology/Mock HIV test and Virtual ELISA test
Mock HIV Test and Virtual ELISA for Lupus Edit
TEACHING OBJECTIVE:
- to illustrate the use of antibodies in the diagnostic ELISA test for HIV and Lupus.
TASK OUTCOMES:
- By the end of this activity, students will be able to:
a. Follow a simplified ELISA test to determine which 'patients' are HIV positive.
b. Follow a detailed virtual lab protocol for the ELISA test for lupus.
c. Outline the use of antibodies in diagnostic medicine.
TIME REQUIRED:
- 60-90 minutes
INTRODUCTION:
The ELISA test detects antibodies to a pathogen in blood serum and shows a positive result with a colour change.
Dilutions of blood serum allow levels of antibodies (and thus the development of the disease) to be estimated.
In this activity, students will carry out a simple test on mock serum samples and will go through all the steps of the ELISA in the virtual lab activity from the Howard Hughes Medical Institution.
ESSENTIAL LINKS
- Description and worksheet for the HHMI virtual lab.
- Direct Link to HHMI Immunology Lab Activity
MATERIALS AND EQUIPMENT:
- Virtual lab: worksheet and internet link to site above (requires Flash)
- Mock HIV Test (for each pair/ group):
- Lead nitrate and potassium iodide solutions
- Dimple tray (min 11 wells)
- 11 x 100ml volumetric flasks, marked A-1:2 A-1:10 A-1:100; B-1:2 B-1:10 B-1:100; C-1:2 C-1:10 C-1:100; Positive Control; Negative Control; HRP
- A set of clean dropping pipettes
INSTRUCTIONS:
- Carry out the mock HIV test first, using it as a chance to explain the method of the ELISA.
- Follow this up with the virtual lab and the worksheet for students to add depth to their knowledge.
Prac Set Up:
- As outlined in the image 'setup'.
- Each group also needs a flask containing 20ml Lead nitrate. Label this 'HRP' (for anti-human antibody).
Instructions
- Explain that serum samples have been collected and diluted and are presented in the flasks. the ELISA plate (dimple tray) has been coated with HIV antigen.
- Add a few drops of 'serum' to the appropriate wells. Take care not to contaminate them.
- Explain at this point that they would normally be washed in buffer, to remove all traces of unattached antibodies.
- To each of the wells, add a few drops of 'HRP. If antibodies are present, a reaction occurs causing a colour change.
- Students record and analyse their results:
Who is positive/ negative/ needs more testing?
SAFETY/ RISK ASSESSMENT
- eye protection for KI and PbNO3
- wash all equipment thoroughly and do not ingest.
- we aren't using real HIV, so don't worry.
IMAGES AND PRAC SETUP
