Development of a Chemotaxis Assay and Identification of Chemotatic Agents in Giardia intestinalis

The waterborne flagellated parasite, Giardia intestinalis, causes approximately 280 million intestinal infections world-wide every year¹. Attachment to the microvilli in the small intestine is believed to cause impairment of absorptive and digestive functions of intestinal cells. There may be a direct correlation between chemotaxis and the mechanism of attachment. Chemotaxis is defined as a cell’s directional change and movement resulting from concentrations gradients of chemoattractants and chemorepellants. This process is uncharacterized in Giardia. By developing a chemotaxis assay for this organism and identifying possible chemoattractants and chemorepellants, we can obtain a better understanding of key molecular processes underlying giardial chemotaxis and assess whether or not chemotaxis plays a role in pathogenicity.  To this end, I am developing a technique to observe and characterize chemically guided movements of G. intestinalis to identify chemotactic agents. Several techniques are being tested including (1) agarose plates, which require cells to swim through low concentration agarose towards or away from a test compound, and (2) capillary techniques in which chemotaxis is assessed as a function of number of cells that swim into a syringe or micropipette containing a chemoattractant. Determining the variants Giardia chemotaxes towards will allow us to research the molecular mechanisms and functional causes governing chemotaxis in Giardia intestinalis and possibly characterize the role of chemotaxis in the establishment of giardiasis.