Fig. 2

Digestion of host DNA increases the sensitivity of parasite detection in parasite-positive human blood samples. (a) Restriction enzyme digestion yields a marked reduction in human 18S rRNA reads per thousand (left panel, greyscale diamonds) and a 5- to 10-fold increase in parasite reads per thousand (right panel, colored circles) in digested relative to undigested samples (n = 3 biological replicates, mean ± SD, samples were normalized according to the reads per thousand for reads derived from human host and parasite separately, with the central dotted line reflective of a zero fold change, which marks the undigested samples before treatment with restriction enzymes). No statistical difference was found for size selection (i.e., > 2 kb vs. < 2 kb) (two-way ANOVA, p = 0.0631). (b) Proportional composition of human DNA dilutions in undigested (ud) and digested (d) samples demonstrates an average 2-fold reduction in human DNA and a 5-fold increase in parasite reads post-digestion (black bars = C. felis, dark grey bars = H. sapiens, light grey bars = P. falciparum, concentration of 3D7 DNA includes P. falciparum and H. sapiens DNA from 3D7 cultures which contain human blood products, two-way ANOVA with Sidak’s multiple comparisons posttest, p < 0.0001, n = 3, mean ± SD)