Strong upregulation of IL-12p40, CXCL9, IL-16, and CCL27, mainly produced by activated mononuclear leukocytes including lymphocytes, monocytes, and dendritic cells, are suggestive of a role for mononuclear leukocytes in pathogenesis of HFRS. Here, CXCL9 is linked to hemorrhagic fever with renal syndrome.