FIG. 1.

Daily parasitemia in A. nancymai monkeys after challenge. Monkeys were vaccinated three times with 50 μg/dose of Pfs25H (a), 50 μg/dose of MSP1₄₂-FVO (b), 50 μg/dose of MSP1₄₂-3D7 (c), or 100 μg/dose of MSP1₄₂-C1 (d). Seventeen days after the final vaccination, they were challenged with 5 × 10⁴ P. falciparum FVO parasitized red blood cells. Parasitemia was monitored daily by inspection of Giemsa-stained thin blood smears until treatment and was calculated based on examination of approximately 2,000 RBCs; if no parasites were seen, then 40 more high-power fields were examined. Monkeys were treated with a curative dose of mefloquine when parasitemia reached 5%, when their hematocrit fell below 25%, or at day 28. T, monkey was treated for high parasitemia; H, monkey was treated for anemia; C, monkey was treated at day 28. D, one monkey in the MSP1₄₂-C1 group was found dead on day 23; the hematocrit on day 21 was 39%, and the parasitemia on day 22 was 0.19%.