Purification of Toxoplasma gondii oocysts by cesium chloride gradient

We describe the use of a cesium chloride (CsCl) gradient as an improvement for the purification of Toxoplasma gondii oocysts from concentrated suspensions. After concentration by sucrose flotation, this technique gives a >96% recovery of very pure unsporulated or sporulated oocysts, but requires fresh oocysts (: 10 weeks of age). This material is suitable for biochemical and immunological analyses of environmentally resistant T gondii oocysts. (C) 2004 Elsevier B.V. All rights reserved.