Intracellular SCARB2 mimicry overcomes decoy failure to broadly inhibit enteroviruses.

Enterovirus A71 (EV-A71) and coxsackievirus A16 (CV-A16) are leading causes of severe hand, foot, and mouth disease (HFMD) with high childhood mortality and no specific antiviral therapy. SCARB2 is the essential uncoating receptor, yet extracellular SCARB2-Fc decoys fail to block infection, representing a decade-old paradox in enterovirus therapeutics. Here, we overcome this limitation by engineering RMP(R8), a cell-penetrating SCARB2 mimetic peptide comprising the minimal VP2-binding domain (W146-K166) fused to an octa-arginine transporter. RMP(R8) shows potent antiviral activity (EC50 = 0.156 μg/mL), outstanding safety (selectivity index > 2003), and excellent aqueous solubility, a critical asset for clinical translation. It broadly inhibits genetically divergent EV-A71 isolates and CV-A16 in intestinal and neural cells by blocking viral entry. In a lethal neonatal mouse model, RMP(R8) increases survival against EV-A71 and CV-A16 challenge in vivo. Intracellular receptor mimicry thus establishes a generalizable strategy for viruses refractory to extracellular intervention. RMP(R8) is a promising clinical candidate to address the unmet need for targeted anti-enterovirus treatment, and our findings redefine how to drug virus-receptor interactions that act inside cells.