IDO2 and chlamydia infectious disease: Next, we explored whether the expression of IFN-γ and IFN-γ induced genes was altered in FP- and BUD-treated lung tissues, including the typical, inducible defence genes against Chlamydia infection, such as indoleamine 2,3-dioxygenase 1 (IDO1), IDO2, MIG/CXCL9, IP-10/CXCL10 and I-TAC/CXCL11.