Taken together, our in vitro findings of increased KKS activation, clinical data demonstrating activation of PK, and the reported successful treatment of patient with severe HFRS due to Puumala virus infection with a BK antagonist [26] implicates BK in the vascular leakage associated with pathogenic HFRS hantavirus infections. This evidence concerns the gene KNG1 and hemorrhagic fever with renal syndrome.