the ultrastructural effects of sulfachloropyrazine on toxoplasma gondii tachyzoites.

background: toxoplasmosis is one of the most common parasitic infections of humans and other mammals. this study was aimed to understand the mechanism of action of veterinary medicine-sulfachloropyrazine (spz, 99.97%) against toxoplasma gondii . methods: t. gondii tachyzoites were soaked in pbs (as a control) or spz (250 mg/ml) for 2 h at 37 °c. after being processed, any ultrastructural changes of the tachyzoites that had occurred were observed by scanning electron microscopy (sem) and transmission electron microscopy (tem). results: the tachyzoites from control groups with a uniform size had a smooth surface and intact cell or nuclear membranes. in addition, an oval-shaped nucleus, conoids and micronemes were also observed. by contrast, many parasites from the spz-treated groups were detrimentally affected by the treatment. some appeared to be of the vacuolization in their cytoplasm, with the substantial re-duction in the number of dense granules and the blur of some organelles. conclusion: the morphology and ultrastructure of tachyzoites can be affected significantly by spz, which might kill the parasite by inhibiting its energy metabolism, inducing apoptosis and damaging its structure . the study provides an experimental basis for further study on the mechanism of spz against t. gondii .