NCAM1 and hemorrhagic fever with renal syndrome: Previous study on PUUV-infected HFRS patients found that the number of CD56+CD16+ NK cells in bronchoalveolar lavage (BAL) fluid of patients was increased, whereas the number of NK cells in the peripheral blood of the PUUV-infected patients decreased at the acute stage of HFRS compared with the healthy individuals [23,24].