Toxoplasma gondii in vitro culture for experimentation

The aim of this study was to develop a culture method for Toxoplasma gondii that could provide fresh viable tachyzoites as and when required. When T gondii was continuously maintained in HeLa cell cultures at 37 degreesC, the time to hat-vest varied from 48 to 144 h. Tachyzoite yields of greater than or equal to1 x 10(6)/ml and greater than or equal to90% viable were obtained from 519/882 (58.8%) cultures and 120/155 (77.4%) harvests were successfully used in the dye test. When cultures were transferred from 37 to 25 degreesC when maximally infected (48-54-h post-infection), they could be stabilised and tachyzoites could be harvested as required, up to 168 11 later. When harvested from 25 degreesC, significantly more cultures 783/811 (96.5%) produced tachyzoite yields greater than or equal to1 x 10(6)/ml greater than or equal to90% viable (p < 0.001). Tachyzoite quality also significantly unproved and 206/224 harvests (91.9%) (p < 0.001) were successfully used in the dye test. We have demonstrated that tachyzoites can be maintained at dye test quality for at least 7 days in HeLa cultures at 25 degreesC. The system is flexible and robust and provides a means whereby tachyzoites of standard quality can be stored for use in experimental models as and when required. (C) 2002 Elsevier Science B.V. All rights reserved.