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

Mock HIV Test and Virtual ELISA for LupusEdit

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



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

Diagram of results - Click for more description
Setup for students- Click for more description
Setup for teachers - Click for more description
Last modified on 3 September 2009, at 05:39