Impact of Zika Virus Infection on Fetal Innate and Adaptive Immunity

PROJECT SUMMARY The objective of this proposal is to define the impact of maternal viral infections and inflammation on immune programming within the fetal brain and lymphoid organs in a well-defined non-human primate (NHP) model. Discoveries in fetal human immunology have primarily come from human cord blood with few studies of fetal blood or the innate immune capacity of major organs. The link between innate immune activation and fetal brain injury is unknown but is of major translational significance to guide novel therapies for fetal protection. Our central hypothesis is that the fetal innate immune programming induced by a maternal ZIKV infection or other infectious triggers initiates a program of cellular stress-response in the fetal brain. This connection between the fetal immune programming and cellular stress-response pathways in the fetal brain has never been studied across gestation or with a suite of diverse and highly sophisticated immunologic tools and platforms. Our preliminary studies in a microculture ex vivo model using human fetal tissues demonstrate active regulation of the innate immune response by Sendai virus (SeV; a model virus inducing innate immune activation) and Zika virus (ZIKV) by 24 hours post-infection. Our preliminary data reveals that 3 days after a maternal ZIKV infection in our NHP model, there is a strong correlation in the fetal brain linking the innate immune response with induction of cellular stress and autophagy. In this proposal, we will use the NHP model to obtain a complete collection of fetal blood and major tissues from the first and third trimesters to interrogate maturation of fetal innate and adaptive immune programming in the fetal brain and major lymphoid organs, which we will link to cellular stress in the fetal brain. In Aim 1, we will use an ex vivo microculture model to determine innate immune pathways activated by model viruses (ZIKV, SeV), Type I IFN (IFN-β), IL-6 and TNF-α in the first and third trimesters within NHP fetal brain and lymphoid organs (fetal brain, placenta, spleen, thymus, blood). In Aim 2, we will use a pregnant NHP model of an acute ZIKV infection to link the profile of fetal innate and adaptive immune activation with production of alarmins and induction of the autophagic response in the fetal brain. In both Aims, we will employ diverse immunologic tools (CyTOF, Nanostring nCounter, Luminex, ELISA, immunohistochemistry, bulk and single cell RNA-Seq) producing high-dimensional data that can be leveraged using bioinformatics to reveal gene networks of innate immune programming that direct viral and inflammatory injury of major fetal organs in early and late gestation, which can inform therapeutic approaches for fetal neuroprotection in the setting of inflammatory preterm birth or congenital viral infection.