ACE2 and viral infectious disease: ACE2 was shown to be associated with the acute lung injury caused by influenza virus.33 In the lung, ACE2 is found primarily in epithelial cells,34 and the ACE2/angiotensin-(1–7)/Mas axis directly regulates epithelial cell survival.35,36 In mice, ACE2 is a mediator of the acute lung injury caused by influenza A H5N1- and H7N9-virus infection,37,38 and in patients, increased ACE2 levels are associated with severe disease.37,39 In mice experimentally infected with H5N1 influenza, treatment with an ARB (losartan) improves survival.33,40