In addition, infection by SARS-CoV-2 or the non-related respiratory syncytial virus (RSV), results in increased AHR and IDO-1 lung expression, concomitant with increased pro-inflammatory gene expression, activation of the Tissue Factor/Plasminogen Activator Inhibitor-1 (TF/PAI-1) signaling pathway, and up-regulation of CYP1A1 (98). This evidence concerns the gene IDO1 and infection.