Figure 2.

Distribution of luciferase expressing Δpm4⁺ and wt⁺ parasites in live mice as visualized by real time in vivo imaging through measurement of luciferase activity. A: A time course of an atypical distribution pattern of schizonts in mice with synchronous infections of Δpm4⁺ and wt⁺ parasites at different time points (hours) after the injection of purified merozoites. Schizont sequestration at 19 and 21 hours in wt⁺-infected mice (belly fat tissue, lungs, and spleen) and reinvasion of ring forms at 23 and 25 hours, resulting in bioluminescence in the whole body. In Δpm4⁺ parasites schizont sequestration and invasion start later (21 and 23 hours), but the distribution remains similar. B: Bioluminescence in organs of mice infected either with wt⁺ or Δpm4⁺ and isolated at 21 and 23 hours after infection, respectively. C: Quantification of luciferase signals in organs of mice infected with wt⁺ and Δpm4⁺ (six mice per group) showed no significant differences in parasite distribution. D: Parasite load and distribution in mice treated with IgG obtained from Δpm4 convalescent mice and infected with wt⁺⁺ parasites. IgG purified from the serum of animals infected with Δpm4cl6 parasites at day 18 or 40 after injection were given to BALB/c mice at days −1, 0, and + 1 relative to the time of i.v. inoculation with wt⁺⁺ parasites. As a control, mice were treated with IgG from wild-type infected mice obtained at day 18 postinfection. Nontreated: BALB/c mice infected with the wt⁺⁺ parasite line only. Parasites were visualized at day 2 after infection of the mice with the wt⁺⁺ parasites. E: Quantification of luciferase signals in organs of mice (six mice per group) treated with the different IgG samples shows a significant increase in parasite accumulation in the spleen of mice treated with IgG from convalescent animals 40 days postinfection. F: The course of the parasitemia in mice treated with the different IgG samples shows a significant reduction of the parasite load in mice treated with IgG that was collected from convalescent animals (day 40 after infection).*P < 0.05. RLU, relative light unit.