Furthermore, given that the pulmonary artery endothelial dysfunction plays a key role in the initiation and progression of PAH [35-37], utilizing the primary pulmonary endothelial cell-culture system we next delineated the importance of oxidative stress and HIF-1α activation in viral protein mediated up-regulation of PDGF-BB. This evidence concerns the gene HIF1A and pulmonary arterial hypertension.