Zika virus targets human trophoblast stem cells and prevents syncytialization in placental trophoblast organoids

Zika virus (ZIKV) infection during pregnancy results in an increased risk of spontaneous abortion and vertical transmission across placenta results in severe congenital defects in newborns. While the infectivity and pathological effects of ZIKV on the placental trophoblast progenitor cells in early human embryos remains largely unknown. Here, using the human trophoblast stem cells (hTSCs) isolated from human blastocyst, we showed that hTSCs were permissive to ZIKV infection, while resistance to ZIKV increased with differentiation. Combined CRISPR/Cas9-mediated gene knockout and RNA-seq assays, we demonstrated that the intrinsic expression of AXL and TIM-1, as well as the absence of potent interferon (IFN)-stimulated genes (ISGs), contributed to the high sensitivity of hTSCs to ZIKV. Furthermore, using our newly developed hTSC-derived 3 dimensional (3D) placental trophoblast organoid model, we demonstrated that ZIKV infection completely disrupted the structure of mature hTSC-organoids and inhibited syncytialization. Overall, our results clearly demonstrated that hTSCs represented the major target cells of ZIKV, and a possible reduced syncytialization may result from ZIKV infection of early developing placenta. These findings deepened our understanding of the characteristics and consequences of ZIKV infection of trophoblast stem cells in early human embryo. Overall design: The single cells from hTSC-organoids and hTSC-organoids infected with ZIKV at MOI 1 and 10 for scRNA-seq