Separation of toxoplasma cysts from brain tissue and liberation of viable bradyzoites.
A method was developed to separate Toxoplasma gondii cysts from mouse brain tissue and to liberate intact bradyzoites from cysts. Brains were blended in a Waring blender with 20% dextran solution and the homogenate was centrifuged at 4,000 g for 10 min. Cysts present in the sediment were digested by adding an equal amount of a solution containing 1 g NaCl, 1.4 ml HCl, and 1 mg pepsin (1:60,000 assay activity) per 100 ml water, and incubated at 37 C for 1 min. This method is harmless for bradyzoites, as tested by bioassays in mice. It compares favorably with published methods for separating cysts that require 3 centrifugations to achieve similar results.
Freyre
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Department of Parasitology, College for Veterinary Sciences, Montevideo, Uruguay.
D000818:Animals; D001921:Brain / Q000469:parasitology*; D002469:Cell Separation / Q000379:methods*; D002908:Chronic Disease; D051379:Mice; D014122:Toxoplasma / Q000166:cytology / Q000302:isolation & purification*; D014124:Toxoplasmosis, Animal / Q000469:parasitology*