Fig. 2: SCSα is vital for the lytic cycle of T. gondii.

a Endogenous tagging of SCSα confirms its mitochondrial localization. b A 7-day plaque assay to assess the growth of DiCre and Δscsα strains (100 tachyzoites/well and 3 wells for each strain). c The relative size of plaques from (b) (means ± SEM; ****p ≤ 0.0001, Student’s t test). d Intracellular growth of Δscsα in vitro. The strain was cultured for 24 h after infection with HFF cells, and the number of parasites in vacuoles was recorded by IFA (n = 3 independent experiments, means ± SEM; two-way ANOVA). e Virulence tests of DiCre and Δscsα strains in ICR mice (10², 10³, 10⁴, 10⁵, 10⁶ parasites/mouse and 5–8 mice/group). f ICR mice (WT) or immunodeficient mice (BLAB/c nude) infected with DiCre and Δscsα strains (10⁴ tachyzoites/mouse, 5–6 mice/strain). 5 days after infection, the parasite load in the peritoneal fluid was analyzed by qPCR. (means ± SEM; t-test). g Naive or Δscsα-immunized mice were infected with 10⁴ RH-Luc tachyzoites (4 mice in each group). The parasite load of mice was analyzed by the IVIS Spectrum imaging system 5 days after RH-Luc infection. h The bioluminescence signal intensity of mice from (g) was calculated and plotted. i The survival of naive or Δscsα immunized mice infected with RH-Luc (**p = 0.0084, simple survival analysis). j The survival of naive or Δscsα-immunized mice infected with 10⁴ ME49 tachyzoites. Statistical significance was examined by log-rank Mantel–Cox test (*p = 0.0144).