In our PAH transcriptomic analysis, HPV and HCV infection might be important in PAH pathogenesis, which may interact with specific membrane receptors or viral proteins (HPV-E6, HCV-NS5A, and HCV-CORE) to activate MAPK and NOTCH signaling pathways, and in turn to regulate TF expression like IRF9, BLC6, HEY2, and RXRG (Figure 5). This evidence concerns the gene IRF9 and pulmonary arterial hypertension.