Identification of Nectin-4 as a rubella virus entry receptor mediating viral shedding and congenital transmission

Rubella virus (RuV) causes rubella and, when acquired during pregnancy, congenital rubella syndrome (CRS). Despite its clinical significance, the cellular entry mechanism of RuV remains poorly characterized owing to limited knowledge of host receptors, hampering pathogenesis studies and therapeutic development. Here, we identify Nectin-4 as a functional RuV entry receptor through proximity biotin labeling-based proteomics coupled with CRISPR/Cas9 validation. Notably, Nectin-4 is shared with measles virus, revealing convergent evolution in viral entry despite the different viral families. Nectin-4 directly interacts with the RuV envelope glycoproteins through its ectodomain, facilitating receptor-mediated endocytosis following initial calcium-dependent viral attachment. In polarized respiratory epithelial cells, Nectin-4 mediates basolateral viral entry and subsequent apical release of progeny virions, enabling efficient respiratory transmission. Using human placental organoid models, we demonstrate that syncytiotrophoblasts serve as primary targets for transplacental RuV infection, with viral entry significantly inhibited by Nectin-4 blockade. These findings establish Nectin-4 as critical for both horizontal respiratory transmission and vertical maternal–fetal transmission of RuV. Our results provide fundamental insights into RuV pathogenesis and identify Nectin-4 as a promising therapeutic target for CRS. Importantly, the discovery of shared receptor utilization between RuV and measles virus opens new avenues for integrated elimination strategies targeting both pathogens.