Sodium taurocholate cotransporting polypeptide acts as a receptor for hepatitis B and D virus.

Infection of hepatitis B virus (HBV) remains a major public health problem worldwide. Understanding the viral infection and developing antivirals against HBV have been hampered by the lack of convenient culture systems and animal models for the infection. Sodium taurocholate cotransporting polypeptide (NTCP), a key bile acid transporter expressed in liver, was recently identified as a critical receptor for viral entry of HBV and its satellite virus hepatitis D virus (HDV). This finding enabled a reliable cell culture system for the viruses. Detailed studies have shown that NTCP is the major determinant for the species specificity of HBV and HDV at entry level. NTCP is responsible for most sodium-dependent bile salt uptake in liver. The molecular determinant critical for HBV/HDV infection overlaps with that for bile acids transporting on NTCP. We evaluated bile acids as potential antivirals for HBV and HDV infection, and developed bile acid derivatives that effectively block taurocholate transporting as well as viral infections. The discovery that NTCP acts as a receptor for HBV has opens a new door for future studies towards the ultimate goal of curative treatment of HBV infection.