Thus, obtained results indicate that the influenza A(H1N1)pdm09 virus causes endothelial dysfunction with alteration in endothelial protein expression (eNOS, tPA, PAI-1) in the pulmonary vascular endothelium in non-lethal influenza virus infection and requires a new approach to influenza therapy, in particular, the administration of vaso-protective medications in combination with etiotropic therapy. The gene discussed is NOS3; the disease is endothelial dysfunction.