IFNG and chlamydia trachomatis infectious disease: IFN-γ enhances the ability of macrophages to clear chlamydial infections [20], [21] and it is a powerful activator of indoleamine 2,3-dioxygenase (IDO) and inducible nitric oxide sythase (iNOS), which prevent bacterial growth by limiting tryptophan availability and upregulating nitric oxide (NO) production, respectively [22], [23], [24], [25].