Figure 1.
Figure 1. P falciparum growth and proliferation are not inhibited in HbF-containing erythrocytes. (A) Flow cytometry analysis of average number of nuclei per parasite in synchronized, RNase-treated, SYBR Green–stained P falciparum 3D7 IG06 parasites grown in normal adult (AA) and cord blood erythrocytes at 9 to 16, 24 to 28, 30 to 32, and 34 to 36 hpi in 1% O2 demonstrating no significant growth differences using paired analysis in each time point of the cell cycle; N = 6 experiments. (B) Representative Pf3D7 IG06 parasites in thin smears of adult (top) and cord (bottom) blood erythrocytes at 16, 28, 32, and 36 hpi. May-Grünwald-Giemsa stain; scale bars, 10 μm. (C) Parasite multiplication rate (PMR) of Pf3D7 IG06 parasites in cord blood and normal adult blood erythrocytes are similar in 1% O2. PMR in sickle cell trait (AS) RBCs is significantly reduced in low O2; N = 2-3 experiments. (D) Flow cytometry analysis of average number of nuclei per parasite in synchronized, RNase-treated, SYBR Green–stained P falciparum CDPK5 D10 parasites off shield demonstrating equal terminal merozoites in both normal adult and cord blood erythrocytes; N = 2000 infected RBCs counted. (E) Overlap of flow cytometry–based growth curves of average number of nuclei per parasite in synchronized, RNase-treated, SYBR Green–stained Pf3D7 IG06 parasites grown in normal adult (AA) and cord blood erythrocytes at 16, 28, 32, and 36 hpi in 1% and 10% oxygen; N = 3 experiments. (F) Flow cytometry analysis of average number of nuclei per parasite in synchronized, RNase-treated, SYBR Green–stained Pf3D7 IG06 parasites grown in normal adult (AA) and A/HPFH blood erythrocytes at 16, 28, 32, and 36 hpi demonstrating no significant growth difference. (G) Representative Pf3D7 IG06 parasites in thin smears of adult (top) and A/HPFH (bottom) blood erythrocytes at 16, 28, 32, and 36 hpi also demonstrating no difference in morphology. May-Grünwald-Giemsa stain; scale bars, 10 μm. Each colored icon signifies an individual experiment. Error bars are standard error of the mean; ****P = .0001. Avg, average; ns, not significant.

P falciparum growth and proliferation are not inhibited in HbF-containing erythrocytes. (A) Flow cytometry analysis of average number of nuclei per parasite in synchronized, RNase-treated, SYBR Green–stained P falciparum 3D7 IG06 parasites grown in normal adult (AA) and cord blood erythrocytes at 9 to 16, 24 to 28, 30 to 32, and 34 to 36 hpi in 1% O2 demonstrating no significant growth differences using paired analysis in each time point of the cell cycle; N = 6 experiments. (B) Representative Pf3D7 IG06 parasites in thin smears of adult (top) and cord (bottom) blood erythrocytes at 16, 28, 32, and 36 hpi. May-Grünwald-Giemsa stain; scale bars, 10 μm. (C) Parasite multiplication rate (PMR) of Pf3D7 IG06 parasites in cord blood and normal adult blood erythrocytes are similar in 1% O2. PMR in sickle cell trait (AS) RBCs is significantly reduced in low O2; N = 2-3 experiments. (D) Flow cytometry analysis of average number of nuclei per parasite in synchronized, RNase-treated, SYBR Green–stained P falciparum CDPK5 D10 parasites off shield demonstrating equal terminal merozoites in both normal adult and cord blood erythrocytes; N = 2000 infected RBCs counted. (E) Overlap of flow cytometry–based growth curves of average number of nuclei per parasite in synchronized, RNase-treated, SYBR Green–stained Pf3D7 IG06 parasites grown in normal adult (AA) and cord blood erythrocytes at 16, 28, 32, and 36 hpi in 1% and 10% oxygen; N = 3 experiments. (F) Flow cytometry analysis of average number of nuclei per parasite in synchronized, RNase-treated, SYBR Green–stained Pf3D7 IG06 parasites grown in normal adult (AA) and A/HPFH blood erythrocytes at 16, 28, 32, and 36 hpi demonstrating no significant growth difference. (G) Representative Pf3D7 IG06 parasites in thin smears of adult (top) and A/HPFH (bottom) blood erythrocytes at 16, 28, 32, and 36 hpi also demonstrating no difference in morphology. May-Grünwald-Giemsa stain; scale bars, 10 μm. Each colored icon signifies an individual experiment. Error bars are standard error of the mean; ****P = .0001. Avg, average; ns, not significant.

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