Interaction between nucleophosmin and HBV core protein increases HBV capsid assembly

•An interaction between HBV core and B23 is proposed.•Oligomerization of B23 is mandatory for its interaction with HBV core protein.•B23 facilitates HBV core protein assembly and increases capsid stability.•Inhibition of B23 reduces capsid formation and HBV production in HepG2.2.15 cells. Host factors are involved in Hepatitis B virus (HBV) genome replication and capsid formation during the viral life cycle. A host factor, nucleophosmin (B23), was found to bind to HBV core protein dimers, but its functional role has not been studied. This interaction promoted HBV capsid assembly and decreased the degree of capsid dissociation when subjected to denaturant treatments in vitro. In addition, inhibition of B23 reduced intracellular capsid formation resulting in a decrease of HBV production in HepG2.2.15 cells. These results provide important evidence that B23 acts on core capsid assembly via its interaction with HBV core dimers. B23 and Cp149colocalize by cosedimentation through density gradient (View interaction) Cp149physically interacts with B23 by anti bait coimmunoprecipitation (1, 2) B23 and B23bind by blue native page (View interaction) Cp149 and B23bind by cosedimentation through density gradient (View interaction) B23binds to Cp149 by anti bait coimmunoprecipitation (1, 2, 3, 4)