TFRC and hemorrhagic fever with renal syndrome: To further confirm these RBCs are nucleated erythroid cells, the flow cytometry was also applied to detect CD71+CD235a+ cells, which are the erythroid lineage markers as previously reported (14), in PBMCs from 52 HFRS samples (40 HFRS patients including 29 critical HFRS samples, and 23 moderate HFRS samples) and 7 health donors (setting as normal control, NC).