Purification and characterization of Toxoplasma gondii tachyzoite DNA

Toxoplasma gondii DNA from RH strain tachyzoites was purified from contaminating murine DNA by isopycnic density gradient ultracentrifugation in CsCl containing the fluorescent dye Hoechst 33258. Quantitative hybridization studies with DNA from uninfected mice and DNA extracted from oocysts of the ME49 strain of T. gondii confirmed that RH strain DNA could be obtained at least 90% pure with a high recovery. Preliminary characterization studies on such purified DNA showed that it had a G + C content of 50% and was not significantly methylated.