Fig. 2

RNA integrity analyses for P. falciparum in vitro and field samples using Agilent Bioanalyzer Platform. a Agilent Bioanalyzer gel and electropherograms showing comparison of RNA extracted from serially diluted P. falciparum iRBCs (12 hpi, ring stage) demonstrating difference in migration speeds of human (HS) and parasite (PF) 18S ribosomal subunits. Range of parasitaemia was obtained by serial dilution of initial parasitaemia of 5%. Uninfected RBCs are shown as a control. Individual and combined electropherograms for 5, 0.5 and 0.005% iRBCs are shown in blue, red and green rectangles in the right side panel. b Comparison of Agilent Bioanalyzer RIN values of samples from subfigure (a). c Correlation between parasitaemia and 18S-Pf/18S-Hs peak height ratio. Peak height values were obtained from Bioanalyzer electropherograms. Lab dilutions (red dots) are 3D7 RNA samples shown in subfigure (a); Field samples (black triangles) correspond to 171 RNA samples extracted from malaria patient blood collected during TRAC2 study. Parasitaemia were estimated by Giemsa smear microscopic readings. In order to scale the data, the number of iRBCs per microlitre of whole blood (par/µl) for 3D7 Lab dilutions has been calculated from percentage of iRBCs assuming 40% average haematocrit (e.g. 1% parasitaemia ~ 40,000 par/ µl)