SLC35E1 is a putative orphan transporter localized to the Golgi apparatus with antiporter activity and transmembrane transport capabilities 1. Functionally, SLC35E1 plays a critical role in herpes simplex virus 1 (HSV-1) nuclear egress; knockout of SLC35E1 reduces HSV-1 replication and causes aberrant accumulation of perinuclear enveloped virions and mislocalization of the viral nuclear egress complex, indicating SLC35E1 is required for efficient viral de-envelopment 1. Beyond viral biology, SLC35E1 expression is dysregulated across multiple disease contexts. In rectal cancer, SLC35E1 was identified as part of a 42-gene expression signature that predicts response to neoadjuvant chemoradiotherapy with 71% sensitivity and 86% specificity for nonresponders 2. SLC35E1 is among five solute carrier genes significantly associated with papillary thyroid cancer recurrence and serves as an independent prognostic variable for disease-free survival 3. Additionally, SLC35E1 emerges as a critical marker in SARS-CoV-2 infection, distinguishing infected from uninfected nasopharyngeal cells and suggesting involvement in viral immune responses 4. SLC35E1 is also implicated in heroin addiction and major depressive disorder as a dysregulated gene in affected brain tissue 56, indicating broader relevance to neuropsychiatric conditions.