The following "Web lab" simulates the potential spread of HIV through a population of 10 - 30 people. Each participant begins with a virtual sample of body fluid. You will choose the number of HIV+ people within the population. HIV status is assigned randomly by the computer. You will not know who is initially HIV+. A sample of this original fluid, before mixing, is archived by the computer. Each participant will exchange fluid with another participant chosen at random by the computer. The computer will generate three rounds of fluid exchanges and display the results.

Following fluid exchanges, the computer simulates an ELISA (enzyme-linked immunosorbent assay) to determine which fluid samples are now HIV+ and displays the results. Next the detective work begins. Knowing the HIV status of all participants, you should be able to narrow down the list to a few individuals who may have been the original carriers. You can perform an ELISA on fluid archived before the mixes to determine who was initially HIV+.

Multiple Browsers

1. An instructor uses a single browser connected to an overhead projector. With class participation, names are selected and the simulation is run for all to see.

2. In a classroom with computer management software that allows an instructor to "push" their screen onto all the computers in the room, a single simulation is run on the instructor's computer and viewed simultaneously by all students on their individual or shared computers.

3. Each student runs their own copy of the activity in their browser. The specific results will vary, but overall the spread of HIV will be similar in all instances. This would allow using the activity as a self-directed experience by the students, who could then compare their results.

We welcome your comments and suggestions as to how we might improve this activity! Please use the Biology Project Contact form to share your ideas with us.