FOXP3 and Japanese encephalitis: Because IDO may regulate the equilibrium of CD4+Foxp3+ Tregs and IL-17+CD4+ Th17 cells in inflammatory diseases [49, 50], we examined the generation of each CD4+ Th subset, including CD4+Foxp3+ Tregs, IL-17+CD4+ Th17, and IFN-γ+CD4+ Th1 cells, early during JE progression.