ABSTRACT Zika virus (ZIKV) infection is associated with congenital ZIKV syndrome (CZS), including various brain anomalies and microcephaly. Our recent studies suggested that yolk sac (YS)-derived microglia (primary immune cells in the brain) and Peli1 (an E3 ubiquitin ligase) are involved in ZIKV infection and its associated CZS. However, it is unknown whether and how Peli1 contributes to the YS-microglia-mediated spread of ZIKV into brain, whether viral infection affects the normal function of microglia, and how such effects influence neural differentiation. Based on preliminary data, we hypothesize that Peli1 plays a critical role in fetal brain ZIKV infection via promoting YS-microglia-mediated ZIKV dissemination into fetal brain and via altering microglial function to affect neural differentiation. This hypothesis will be tested by two specific aims: 1) to determine how Peli1 promotes ZIKV infection of YS-microglia and virus dissemination from microglia to neural stem cells in fetal brains; and 2) to determine how Peli1 mediates microglial activation and alters neural differentiation after ZIKV infection. This integrative study employs biochemical and genetic manipulations in both in vivo animal models and in vitro mouse and human cell platforms. The outcomes will be evaluated by molecular, cellular, and neuroanatomical analyses. Understanding the molecular mechanisms underlying the role of microglia in ZIKV-related brain infection may lead to identification of new targets for prevention and treatment of ZIKV and other virus-mediated congenital neural infections.