IL10 and lymphopenia: Importantly, the level of IL-10 was significantly increased from 48 hpi (16.5 ± 4.1 pg/mL, n = 3, p = 0.0266) and then continued to increase until the deaths of the infected mice at 72 hpi (57.6 ± 4.0 pg/mL, n = 3, p = 0.0002) when compared with the mock mice (2.3 ± 0.7 pg/mL, n = 3), which not only coincided with the onset of the viral RNA level in the serum but also coincided with the onset of lymphopenia (Supplementary Figure S5).