STEM-12. ZIKA VIRUS TARGETS GLIOBLASTOMA STEM CELLS THROUGH A SOX2-INTEGRIN α vβ 5 AXIS

INTRODUCTION Oncolytic virus hold great promise as a platform for glioblastoma therapeutic development. Zika virus (ZIKV) is an oncolytic virus with exquisite selectivity for infecting and killing glioblastoma stem cells (GSCs). Here, we delineate the molecular determinant of this selectivity. METHODS cell-based glioblastoma models, glioblastoma organoid assays, in vivo murine glioblastoma models, ZIKV infectivity assays, gene silencing, ChIP-seq studies. RESULTS In independent models, ZIKV preferentially infected and lysed SOX2+ GSCs. Silencing of SOX2 expression attenuated this preferential infectivity. Of note, ZIKV infection of GSCs was independent of AXL, its putative receptor in normal brain. ChIP-seq experiments revealed that SOX2 bound within the ITGAV locus (encoding the integrin av subunit), and this binding was associated with accumulation of the active chromatin mark H3K27ac. Silencing of SOX2 suppressed ITGAV expression as well as ZIKV infectivity against GSCs, indicating that integrin is required for ZIKV infection. Of integrin b units, only silencing of integrin b5 prevented the killing of GSCs by ZIKV infection, suggesting ZIKV infection required the avb5 integrin. Supporting this hypothesis, blockade of the avb5 integrin substantially reduced ZIKV infection of GSCs in glioblastoma organoid assays and in clinical glioblastoma specimens. Sox2 expression additionally suppress GSC expression of all members of the interferon-stimulated genes (ISG family), thereby suppressing innate anti-viral response to facilitate ZIKV infection. CONCLUSIONS Collectively, our results reveal that ZIKV infection of GSCs is mediated by integrin α vβ 5 leading to SOX2 expression which negatively regulates antiviral immunity thereby facilitating ZIKV infection.