Isolation and Purification of Toxoplasma gondii Tachyzoites

Toxoplasma gondii tachyzoites of the parental RH∆ku80 (referred as RH) stain, PYS (ToxoDB#9, Chinese I) strain and gene mutant strains were maintained in confluent monolayers of human foreskin fibroblasts (HFFs, ATCC SCRC-1041^TM) maintained in DMEM supplemented with 2% fetal bovine serum (FBS, Gibco, Auckland, New Zealand), 10 mM HEPES (pH 7.2, Solarbio, Beijing, China), 100 U/mL of penicillin (Solarbio, China) and 100 μg/mL of streptomycin (Solarbio, China) as described previously [20 (link),21 (link)]. For further study, the tachyzoites were isolated and purified by 27-gauge needles (BD Medical, Franklin Lake, WI, USA) and Millipore filters (Merck-Millipore, Darmstadt, Germany) with a pore size of 5 µm. Tachyzoites were counted by hemocytometer measurement and diluted to required number of tachyzoites in 200 μL PBS or DMEM [22 (link)].