KLRD1 and hemorrhagic fever with renal syndrome: The ex vivo co-culture of purified NK cells from the PBMCs of HFRS patients and HTNV peptide pulsed K562/HLA-E*0103 cells was then conducted to find out the direct evidence that interaction between CD94/NKG2A and HLA-E/HTNV peptide complex would affect the antiviral ability of CD56dimNKG2A+ NK cells.