Necroptosis-based CRISPR Knockout Screen Reveals Neuropilin-1 As a Critical Host Factor for Early Stages of Murine Cytomegalovirus Infection.

Significance Human cytomegalovirus (HCMV) is a β-herpesvirus that establishes life-long infection, leaving the risk of persistent reactivation and disease. Inhibition of viral entry into susceptible cells is an attractive strategy to prevent infection. MCMV is a surrogate to model host-pathogen interactions; however, the precise mechanism of MCMV entry remains incomplete. Here, we utilized a pronecroptotic form of MCMV as a strategy to perform a genome-wide forward genetic screen to identify host factors essential for infection. We characterize VEGF receptor Nrp-1 as a novel mediator of MCMV infection required for viral gene expression, replication, and necroptosis induction. Our observations define Nrp-1 as a key cellular factor that facilitates MCMV infection and may be an entry receptor for the virus. Herpesviruses are ubiquitous human pathogens that cause a wide range of health complications. Currently, there is an incomplete understanding of cellular factors that contribute to herpesvirus infection. Here, we report an antiviral necroptosis-based genetic screen to identify novel host cell factors required for infection with the β-herpesvirus murine cytomegalovirus (MCMV). Our genome-wide CRISPR-based screen harnessed the capacity of herpesvirus mutants that trigger antiviral necroptotic cell death upon early viral gene expression. Vascular endothelial growth factor (VEGF) and semaphorin-binding receptor Neuropilin-1 (Nrp-1) emerge as crucial determinants of MCMV infection. We find that elimination of Nrp-1 impairs early viral gene expression and reduces infection rates in endothelial cells, fibroblasts, and macrophages. Furthermore, preincubation of virus with soluble Nrp-1 dramatically inhibits infection by reducing virus attachment. Thus, Nrp-1 is a key determinant of the initial phase of MCMV infection.