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

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Mock HIV Test and Virtual ELISA for Lupus[edit | edit source]


  • to illustrate the use of antibodies in the diagnostic ELISA test for HIV and Lupus.


  • 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.


  • 60-90 minutes

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.



  • 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


  • 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).


  • 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?


  • eye protection for KI and PbNO3
  • wash all equipment thoroughly and do not ingest.
  • we aren't using real HIV, so don't worry.


Diagram of results - Click for more description
Diagram of results - Click for more description
Setup for students- Click for more description
Setup for students- Click for more description
Setup for teachers - Click for more description
Setup for teachers - Click for more description