Our previous work has shown that the overexpression of the negative co-stimulatory molecule PD-1 and the PD-L1 ligand is closely related to idiopathic pulmonary arterial hypertension (iPAH) and the presence of Epstein-Barr virus (EBV) reactivation markers [18]. The gene discussed is CD274; the disease is idiopathic pulmonary arterial hypertension.