However, when stimulated with the polyclonal activator SBE as control, both CD4+ and CD8+ T cells of the HFRS patients presented proliferative activity with a large proportion of CFSEdim cells (representative in Fig 7A and others in S9 Fig), which was obviously higher than that stimulated with HTNV-Gn/Gc peptides (S10 Fig, P = 0.0049 for CD4+T cell and P = 0.0005 for CD8+T cell), suggesting that the impaired T-cell expansion in severe/critical HFRS patients may be refractory to the specific HTNV-Gn/Gc stimulation, but not susceptible to a systemic cell death after activation. This evidence concerns the gene CD4 and hemorrhagic fever with renal syndrome.