Differential growth of Toxoplasma gondii isolates in ovine trophoblast AH-1 cells. A Parasite invasion rate at 4 and 8 hpi and total parasite invasion rate at 56 hpi (pInvR4h, pInvR8h, and pInvRT, respectively) of TgShSp1, TgShSp2, TgShSp3, TgShSp11, TgShSp16 and TgShSp24 isolates infecting AH-1 cells. Parasite infection rates were defined as the percentage of invading tachyzoites (number of infection events per well) at the different time points for each isolate. Each column and error bar represent the mean and the SD of 3 replicates from 3 independent assays at the indicated sampling times. B Proliferation kinetics of each of the isolates in AH-1 cells. The number of tachyzoites/ng of total DNA reached at specific times after infection (8, 24, 32, 48, 56, 72, 80 and 96 hpi) by each isolate is represented. TgShSp1 vs. TgShSp24 at 32 h (p < 0.01), 48 h (p = 0.0001), 56 h (p < 0.0001), 72 h (p < 0.0001), 80 h (p < 0.0001), and 96 h (p < 0.001); TgShSp2 vs. TgShSp24 at 56 h (p < 0.05), 72 h (p < 0.001), 80 h (p < 0.01), and 96 h (p < 0.001). C, D Tachyzoite yield at 72 hpi (TY72h) reached by each isolate. TY72h mean values for each isolate are tabulated. *p < 0.05; **p < 0.01; ***p < 0.001; ****p < 0.0001.