Identification of TPRA1 as a Novel Receptor and Predictive Biomarker for Oncolytic Virus M1.

Viral receptors are essential host factors that determine the tropism of oncolytic viruses, and contribute to their selective targeting of cancer cells. In this study, a membrane protein-targeted CRISPR-Cas9 screen is conducted and identify transmembrane protein adipocyte-associated 1 (TPRA1) as a novel receptor for oncolytic virus M1(OVM), a promising oncolytic virus currently under clinical investigation. Mechanistically, TPRA1 facilitates OVM infection by promoting both viral attachment and internalization. Extracellular region of TPRA1 directly binds OVM particles via glycosylation, while its cytoplasmic tail mediates virus endocytosis, collectively enabling efficient viral entry and cancer cell lysis. Importantly, TPRA1 expression in cell lines, mouse models, and patient-derived tumor samples are positively correlated with their respective sensitivity to OVM, and TPRA1 is upregulated in a high proportion of tumors compared to adjacent normal tissues, highlighting its potential as a therapeutic response biomarker. Furthermore, TPRA1 also promotes the entry of Semliki Forest Virus, suggesting its conserved role in alphavirus infection. Together, these findings establish TPRA1 as both a mechanistic determinant of OVM tropism and a biomarker to guide patient selection in clinical trials of OVM-based therapy.