Current evidence suggests that probiotics/prebiotics can improve microbial translocation, regulate intestinal microbes, promote CD4+ T cell reconstitution, and reduce the activity of indoleamine 2,3-dioxygenase-1 (IDO-1), contributing to the protection of Th17 cells during infection (Vujkovic-Cvijin et al., 2015; Ortiz et al., 2016). The gene discussed is IDO1; the disease is infection.