Fig. 2

Knockout of MCA1 and MCA2 affected the growth of the tachyzoites. a Plaque assay of Δmca1, Δmca2, Δmca1Δmca2, and Δku80 tachyzoites. Each well of HFF was infected with 500 parasites and plaques were stained 7 days later. The plaque of Δmca1Δmca2 was not obvious compared to the other strains, which explained the defective proliferation of double-knockout strain. b Intracellular replication assay of Δmca1, Δmca2, Δmca1Δmca2, and Δku80 strains. A total of 100 PVs of each strain were counted, and data compiled from three independent assays were analyzed. X-axis is the number of tachyzoites in each PV. Y-axis is the percentage of PVs with different number of tachyzoites. *P < 0.5 was significant by the chi-square test. c Motility assay of Δmca1Δmca2 and Δku80. The motility was observed using IFA as the surface protein SAG1 was left behind with the motion of the parasites. The motility of Δku80 (top panel) was normal for most of the parasites had gliding and cycling motion. However, the double-knockout strain Δmca1Δmca2 (middle and bottom panel) showed abnormal morphology, with almost round shape of the extracellular parasites, and the abnormal extracellular parasites showed defective motility without any gliding and cycling motion. The scale bar from top to bottom panel: 2.5 μm, 2 μm and 3 μm