While it is evident that Ct does not completely evade immune responses, it remains unclear if the induction of a strong type I IFN response by ECS cells at 24hpi is sufficient to clear infection, facilitate infection, or encourage persistence by regulating indoleamine 2,3-dioxygenase (IDO), the induction of which depletes tryptophan, an essential amino acid required for Ct growth and replication (Puccetti, 2007; Trinchieri, 2010; Bommana et al., 2021). This evidence concerns the gene IDO2 and infection.