OM-7D3-B3 is a monoclonal antibody targeting human claudin-1 (CLDN1) (Kd = 4 nM) . OM-7D3-B3 blocks the process in which CLDN1 is involved in the entry of hepatitis C virus (HCV) into cells. OM-7D3-B3 is promising for research of HCV infection[1][2].