NitricOxide (NO), mainly produced by epithelial and white blood cells (iNOS) and to a lesser extent by endothelial cells (eNOS), is able to significantly reduce viral infection and replication of SARS-CoV in normal condition through two distinct mechanisms: impairment of the fusion between the spike protein and its receptor ACE2, and reduction of viral RNA production [40]. Here, ACE2 is linked to viral infectious disease.