Interestingly, analysis of the serological status of the study participants revealed that all IPAH patients with positive EBV DNA results had antibody titres indicating a viral reactivation, assessed as described by De Paschale et al. [27] Samples of all of them were positive for anti-VCA IgM, anti-VCA IgG, and anti-EBNA-1 IgG, while results of anti-EA IgM and anti-EBNA-1 IgM were negative. The gene discussed is CD40LG; the disease is idiopathic pulmonary arterial hypertension.