Fig 4. ZIKV-DAK detection in MFI and fetal tissues and fluids.

A) Illustration of the rhesus macaque conceptus depicting evaluated tissues and fluids. The pregnant uterus is lined by the maternal endometrium of pregnancy called the decidua. The layers of the placenta are shown as the trophoblastic shell where the trophoblasts and the decidua meet, the placental villi, and the chorionic plate made up of the chorion and large fetal vessels. The chorionic membrane is the outer fetal membrane and the inner fetal membrane is the amniotic membrane. As the fetus grows the amniotic membrane is pushed up against the chorionic membrane and the membranes are fused. Fused fetal membranes were only observed in one case, 45/14-4. B) ZIKV RNA burden as detected by RT-qPCR on RNA isolated from indicated tissues and fluids. The level of ZIKV burden is summarized as high (>1000 ZIKV RNA copies/mg of tissue or mL of fluid), medium (>100 ZIKV RNA copies/mg or mL), low (< 100 ZIKV RNA copies/mg), or below the limit of detection. The limit of detection for all the fluids listed (CSF, amniotic fluid, umbilical cord blood) is 150 copies/mL. The theoretical limit of detection for all of the tissues is 3 copies/mg. Placental viral loads are presented as the mean of three tissue biopsies per disc. Placental biopsies represent a general survey of the placenta as these samples contain maternal blood, chorionic plate, and portions of the trophoblastic shell in addition to placental villi. C) ZIKV RNA presence as detected by ISH. ZIKV RNA was noted as present (+) or absent (-) in the indicated tissues. In some instances, a histological sample was not obtained, thus ZIKV RNA presence or absence could not be properly evaluated (/).