IB Biology Practical Investigations/Human Health and Physiology/Mock HIV test and Virtual ELISA test

Mock HIV Test and Virtual ELISA for Lupus
TEACHING OBJECTIVE: 
 * to illustrate the use of antibodies in the diagnostic ELISA test for HIV and Lupus.

TASK OUTCOMES: a. Follow a simplified ELISA test to determine which 'patients' are HIV positive.
 * By the end of this activity, students will be able to:

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:  Prac Set Up:
 * 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.
 * 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