Recently we showed that PHT cells and cells pre-exposed to PHT medium are also resistant to infection by Zika virus (ZIKV), an effect mediated by the constitutive release of the type III interferons (IFN) IFN lambda-1 and IFN lambda-2 in trophoblastic medium.
In addition, we found that fetuses lacking type III IFN-λ signaling had increased ZIKV replication in the placenta and fetus when infected at E12, and reciprocally, treatment of pregnant mice with IFN-λ2 reduced ZIKV infection.
Here, we developed 3D cell-line-based models of human syncytiotrophoblasts, cells that lie in direct contact with maternal blood, and show that these cells recapitulate the antiviral properties of primary trophoblasts through the constitutive release of type III IFNs (IFNλ1 and IFNλ2) and become resistant to ZIKV infection.