Fig. 4: Knockout of SDHA is detrimental for the parasite.

a A 6-day plaque assay to assess the growth of DiCre and Δsdha strains (100 tachyzoites/well and 3 wells for each strain). b The relative size of the plaques from (a). c The replication efficiency of DiCre and Δsdha strains in HFF cells were compared. The parasized HFF cells were cultured for 24 h, and the number of parasites in the vacuoles was determined by IFA. (n = 3 independent experiments, means ± SEM; ****p ≤ 0.0001, two-way ANOVA). d WT mice (ICR) or immune-deficient mice (BLAB/c nude) were infected with DiCre and Δsdha mutants (10⁴ tachyzoites/mouse and 5 mice/strain). Parasite loads in peritoneal fluid were calculated by qPCR after 5 days of infection. The results are mean ± SEM. ****p ≤ 0.0001, Student’s t test. e Virulence test of ICR mice infected with DiCre or Δsdha parasites (100 tachyzoites/mouse and 10 mice/strain). f Virulence test of ICR mice infected with a dose of 10³ parasites of the specified strains (8 mice). The Δsdha mutant was also inoculated at higher doses (10⁴, 10⁵, 10⁶ parasites/mouse; 5 mice/group). g Naive or Δsdha-immunized mice were infected with 10⁴ RH-Luc tachyzoites (3 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 (means ± SEM; ****p ≤ 0.0001, Student’s t test). i The survival of naive or Δsdha immunized mice infected with RH-Luc. j The survival of naive or Δsdha-immunized mice infected with ME49 tachyzoites (10⁴).