IDO is induced during HIV infection in activated dendritic cells and monocytes by interferons and toll-like receptors ligands such as LPS and sCD14, catabolizing tryptophan into kynurenine and other immunologically active catabolites; these catabolites suppress T cell proliferation and/or differentiation, resulting in impairment of the mucosal immunity. The gene discussed is IDO1; the disease is HIV infectious disease.