Figure 1.
Parasite developmental age and infected erythrocyte knob density.
Example atomic force micrographs of erythrocytes infected by a early schizont parasite ex vivo (A) or by a younger VAR2CSA-expressing trophozoite (B). Black scale bars: 1 µm. The inserts show light micrographs of the same infected erythrocytes stained by Giemsa. Close-up micrographs of knobs (C) and of a single knob (D). Black scale bars: 200 nm (C), 75 nm (D).
Figure 2.
The density of knobs on the surface of erythrocytes infected by ex vivo isolates of P. falciparum obtained from Ghanaian acute malaria patients.
The relationship between time since invasion (h) and IE surface knob density (µm–2) on erythrocytes infected by 14 genotypically distinct isolates of P. falciparum (isolate name in brackets), cultured in vitro for less than 30 h (A-N). Individual data points, as well as the linear regression line (with 95% confidence limits) for data points <36 h are shown for each isolate.
Figure 3.
Covariance analysis of the relationship between knob density and time since invasion.
All time/density data points <36 h as well as the common regression line (with 95% confidence interval) for the Ghanaian ex vivo isolates (A) and the laboratory isolates selected for VAR2CSA expression in vitro (C). Adjusted regression lines (assuming parallelism) of individual Ghanaian (B) and VAR2CSA-expressing isolates (D).
Figure 4.
The density of knobs on the surface of erythrocytes infected by long-term in vitro isolates of P. falciparum expressing the PfEMP1 protein VAR2CSA.
The relationship between time since invasion (h) and IE surface knob density (µm–2) on erythrocytes infected by 10 genotypically distinct isolates of P. falciparum (isolate name in brackets), maintained in long-time in vitro culture and selected for expression of the PfEMP1 protein VAR2CSA by regular panning for IE adhesion to CSA (A-J). Individual data points, as well as the linear regression line (with 95% confidence limits) for data points <36 h are shown for each isolate.
Figure 5.
The density of knobs on the surface of erythrocytes infected by isolate GH18 after prolonged culture in vitro.
The relationship between time since invasion and IE surface knob density after in vitro culture of isolate GH18 for 8 weeks (A) or 12 weeks (B). All time/density data points <36 h as well as the common regression line (with 95% confidence interval) for the GH18 (note that the ex vivo data points shown in Fig. 2M are included) (C). Individual data points, as well as the linear regression line (with 95% confidence limits) for data points <36 h are shown. Adjusted regression lines (assuming parallelism) after different times of in vitro culture of isolate GH18 (D).