Comparison of Eight Cell-Free Media for Maintenance of Toxoplasma gondii Tachyzoites.

Background: Toxoplasmosis is considered as one of the most common infectious diseases caused by the protozoan parasite Toxoplasma gondii. Tachyzoite is the main form of Toxoplasma and continuously is maintained in cell culture or injected into the mice peritoneal cavity. This study was designed to evaluate the survival rate of RH strain of T. gondii tachyzoites in different cell free, nutrient and biological media at different temperatures.

Methods: This experimental study was performed at the Toxoplasmosis Research Center, Mazandaran University of Medical Sciences, Sari, Iran, in 2010. One ml of each solution including hypotonic saline (0.3%), normal saline (0.85%), RPMI-1640 (RPMI), RPMI with 10% fetal bovine serum (FBS), RPMI with 20% FBS, ovine hydatid cyst fluid, pasteurized milk of cow, and phosphate buffered saline (PBS) along with 4×10(4) T. gondii tachyzoites were added to plate wells and incubated in 4 °C, 22 °C, 37 °C, and 37 °C under 5% CO2. The survival rate and viability assessment of parasites were performed daily and the results were analyzed using Univariate tests.

Result: Tachyzoites survival rate in PBS (4 °C) and normal saline (4 °C) were considerably high, compared to other solutions in different conditions (P<0.001). The best temperature for Toxoplasma maintenance was 4 °C (P<0.001).

Conclusion: This study introduces two available and economical solutions, PBS (4 °C) and normal saline (4 °C) media, for maintenance of Toxoplasma tachyzoites as appropriate choice media for a noticeable period of time (11 days) in vitro.