Dynamac, Inc. 1 article published in JoVE Immunology and Infection Obtaining Highly Purified Toxoplasma gondii Oocysts by a Discontinuous Cesium Chloride Gradient Sarah E. Staggs1, Mary Jean See2, J P. Dubey3, Eric N. Villegas2,4 1Dynamac, Inc., 2Department of Biological Sciences, University of Cincinnati, McMicken College of Arts and Science, 3Animal Parasitic Disease Laboratory, Agricultural Research Service, U.S. Department of Agriculture, 4National Exposure Research Laboratory, US Environmental Protection Agency This study describes the development of a modified CsCl method that easily purifies T. gondii oocysts from feces of infected cats that are suitable for molecular biological and tissue culture manipulation