IDO1 and AIDS: Strikingly, indoleamine 2,3-dioxygenase 1 (IDO1) activity is significantly elevated in both HIV and Mtb infection, correlating with AIDS and TB diseases (Favre et al., 2010; Drewes et al., 2015; Gostner et al., 2015; Jenabian et al., 2015; Routy et al., 2015; Dagenais-Lussier et al., 2016; du-Gyamfi et al., 2017; Gautam et al., 2018; van Laarhoven et al., 2018).