Figure 1. Immunization with attenuated parasites.

(A) Immunodeficient SCID mice (left panel) or immunocompetent A/J mice (right panel) were administered 10⁶ (left panel) or 10⁷ (right panel) P. chabaudi prbcs attenuated with 2 μM centanamycin or 10⁷ WT parasites (right panel). qPCR was performed to estimate parasite density in the blood at various time points. y axes show the estimated parasite density. (B) To assess immunity, A/J mice (5 per group) were immunized with a single dose of 10⁶P. chabaudi prbcs attenuated with centanamycin, TH-III-149, or AS-VIII-104, as indicated, or left untreated. All were challenged 5 weeks later with 10⁵P. chabaudi prbcs i.v. (C) To assess immunity in a different mouse strain, C57BL/6 mice were either immunized with a single dose of 10⁶P. chabaudi prbcs attenuated with centanamycin or given a saline injection (control) and challenged 9 weeks later with 10⁵P. chabaudi prbcs i.v. (D) TH-III-149 (for P. vinckei challenge) or centanamycin (for P. yoelii challenge) were used to attenuate P. chabaudi, and mice were immunized with a single dose of 10⁶ prbcs and challenged 4 weeks later with either 10⁴P. vinckei or 10⁴P. yoelii prbcs i.v. Plus signs indicate that mice succumbed to the infection.