ObjectiveTo explore the inhibitory effect of artesunate (Art) on an in vitro cultured model of Toxoplasma Gondii infection.

MethodsAn in vitro infection model was established by infecting macrophages (Mφ) in the peritoneal cavity of mice with Toxoplasma Gondii RH strain expressing stable green fluorescent protein in the cytoplasm (RH-GFP).The experiment was divided into four groups: control group (0.9% sodiuom chloride solution), Art group (concentrations of 1.562 5, 3.125, 6.25, 12.5, 25, 50, 100 and 200 μg/mL), Azithromycin (Azm) group (positive control, concentrations of 12.5, 25, 50, 100, 200, 400, 800 and 1 600 μg/mL), Art+Azm group (concentrations of Art 1.562 5+Azm 12.5, Art 3.125+Azm 25, Art 6.25+Azm 50, Art 12.5+Azm 100, Art 25+Azm 200 and Art 50+Azm 400 μg/mL.After 24 hours of incubation, the change in proportion of parasites and cells was detected by flow cytometry, and the morphology and structural changes of tachyzoites were observed by Giemsa staining.

ResultsCompared with the control group, the proportion of tachyzoites in the Art group decreased significantly with the increase of concentration from 3.125 μg/mL (P < 0.01), the proportion of free parasites was less than 0.3% at 50 μg/mL, and the infection rate of Mφ was less than 1.6%.In Azm group, the proportion of tachyzoites was less than 0.6% at 400 μg/mL, and the infection rate of Mφ was less than 3.5%.In the Art+Azm group, the proportion of tachyzoites in the Art 12.5+Azm 100 μg/mL group was less than 0.04%, and the infection rate of Mφ was less than 1.8%.Giemsa staining showed that with the increase of concentration in each group, the Toxoplasma Gondii tachyzoites gradually swelled and transformed from a banana shape to one with foamy cytoplasm.The internal structure collapsed and disintegrated until the cell membrane ruptured and contents spilled out, and only the solidified and deeply stained nuclei or fragments remained in the field of view.

ConclusionsArt can significantly kill the free tachyzoites of Toxoplasma Gondii in vitro experiment and reduce the infection rate of host cells, and the anti-Toxoplasma Gondii effect is positively correlated with the concentration within a certain range.