FIG 4.

ZIKV viral burden in the peripheral organs and CNS is reduced with prior flavivirus exposure. Ifnar1^−/− mice were sublethally infected with either ZIKV (n = 10), DENV2 (n = 10), DENV3 (n = 10), YF-17D (n = 10), or PBS as a flavivirus-naive control (n = 10). Thirty days following primary infection, mice were challenged with ZIKV by i.v. administration. At days 4 and 8 post ZIKV challenge (n = 5 mice per group per day), mice were euthanized, perfused with PBS, and organs were weighed and snap-frozen. RNA was extracted, and qRT-PCR was performed to measure viral burden in the spleen (A), liver (B), kidney (C), brain (D), and spinal cord (E). (F) Infectious virus was quantified in the spleen and brain homogenates of infected mice on days 4 and 8 post ZIKV challenge, respectively, via a standard FFA. Data are displayed as Log₁₀ ZIKV genome copies per milligram of tissue. Statistical significance was determined by Mann-Whitney test (*, P = 0.03; **, P = 0.002; ***, P = 0.0002; ****, P < 0.0001).