Cellular entry of the hepatitis B and D viruses (HBV/HDV) requires binding of the viral surface polypeptide preS1 to the hepatobiliary transporter Na⁺-taurocholate co-transporting polypeptide (NTCP). This interaction can be blocked by bulevirtide (BLV, formerly Myrcludex B), a preS1 derivative and approved drug for treating HDV infection. Here, to elucidate the basis of this inhibitory function, we determined a cryo-EM structure of BLV-bound human NTCP. BLV forms two domains, a plug lodged in the bile salt transport tunnel of NTCP and a string that covers the receptor’s extracellular surface. The N-terminally attached myristoyl group of BLV interacts with the lipid-exposed surface of NTCP. Our structure reveals how BLV inhibits bile salt transport, rationalizes NTCP mutations that decrease the risk of HBV/HDV infection, and provides a basis for understanding the host specificity of HBV/HDV. Our results provide opportunities for structure-guided development of inhibitors that target HBV/HDV docking to NTCP.

乙型肝炎和丁型肝炎病毒 (HBV/HDV) 进入细胞需要病毒表面多肽 preS1 与肝胆转运蛋白 Na ⁺ -牛磺胆酸共转运多肽 (NTCP) 结合。这种相互作用可以被 bulevirtide（BLV，以前的 Myrlucex B）阻断，bulevirtide 是一种 preS1 衍生物，已被批准用于治疗 HDV 感染。在这里，为了阐明这种抑制功能的基础，我们确定了 BLV 结合的人 NTCP 的冷冻电镜结构。 BLV 形成两个结构域，一个位于 NTCP 胆汁盐运输通道中的塞子和一个覆盖受体细胞外表面的绳索。 BLV 的 N 端肉豆蔻酰基与 NTCP 的脂质暴露表面相互作用。我们的结构揭示了 BLV 如何抑制胆汁盐转运，合理化 NTCP 突变以降低 HBV/HDV 感染风险，并为了解 HBV/HDV 的宿主特异性提供基础。我们的结果为靶向 HBV/HDV 与 NTCP 对接的抑制剂的结构指导开发提供了机会。