Plasmodium infection increased platelet Ido1. (A) Heat map of RNA-seq for IDO1 expression in platelets isolated from patients infected with P vivax and healthy controls. Individual bars represent samples derived from 7 controls and 7 patients with P vivax infection. (B) Percentage of SYBR⁺ parasitized RBCs measured at multiple time points using flow cytometry. (n = 5, ∗P < .05). (C) Platelet counts were obtained on multiple days after infection and expressed as fold change vs uninfected controls (n = 5). (D) RNA-seq of mouse platelets also revealed changes in Ido1 in a mouse infection model. (E) Platelet RNA was isolated from PyNL-infected mice and polymerase chain reaction performed for Ido1 expression at multiple time points. (∗P < 0,5, ∗∗P < .01, and ∗∗∗∗P < .0001).