P chabaudi infection kinetics and survival in ferrochelatase knockdown mice. Parasitemia of P chabaudi–infected female (A) and male (C) mice. Data (±SE) represent the mean percentage of infected red cells in mice on the indicated day following inoculation with P chabaudi blood-stage parasites. The strains of mice used (all on a C57BL/6 genetic background) were (n = female and male): Fech^+/+ (WT, n = 22 and 20), Fech^+/m1Pas (Het, n = 17 and 23), and Fech^m1Pas/m1Pas (Mut, n = 12 and 16). There was a significant difference between Fech^m1Pas/m1Pas mice and both the Fech^+/+ and Fech^+/m1Pas strains at the day of peak infection (female, day 6, P < .01; male, day 8, P < .01). All parasitemias returned to 0 in surviving mice. Survival of P chabaudi–infected female (B) and male (D) mice. Mice were infected with P chabaudi and monitored for survival over the time period indicated. The mice used were the same as those used to study the parasitemias above. There was a significant difference in survival between Fech^m1Pas/m1Pas mice and both Fech^+/+ and Fech^+/m1Pas strains (female, P < .01; male P < .01). SE, standard error; WT, wild type.