Administration of a live dengue vaccine to healthy subjects upregulates platelet IFITM3. (A) Schematic of the dengue vaccination clinical trial. After providing informed consent, healthy subjects were randomized to receive either a live, attenuated dengue vaccine (TV003, n = 17) or placebo injection (Placebo, n = 8) in a 2:1 randomization scheme. Investigators were blinded to study group assignment. Immediately before injection (day 0 [D0]) and again 14 days after injection (D14), whole blood samples were drawn from subjects. Purified platelets were isolated as described in “Methods.” (B) IFITM3 expression was measured by using quantitative RT-PCR in isolated platelets. The graph shows the change in IFITM3 expression on D14, compared with D0 levels. (C) Schematic of the influenza vaccination study. Whole blood samples were drawn from healthy subjects (n = 8) immediately before (D0) receiving the 2012 to 2013 inactivated influenza vaccine and again 14 days (D14) after vaccination. Purified platelets were isolated as described in “Methods.” (D) IFITM3 expression was measured by using quantitative RT-PCR in isolated platelets.