Figure 3.

Changes in VAR4 surface expression and transcription of the 3D7_SM subline left to drift (3D7_SM-drift). Left Y-axis, percentage of infected blood cells positive for VAR4 using flow cytometry and VAR4-specific CIDR1α (closed circle) and DBL5δ (open triangle) rabbit antibodies. Right Y-axis, percentage var4 gene transcription in ring stage (closed square) parasites calculated as: (var4 absolute copy number/∑copy number of all 3D7 var genes) × 100%. Fluorescence of 3D7_SM-drift stained with pre-immune serum was used to separate positive cells from cells with background fluorescence.