Nervous necrosis virus capsid protein exploits nucleolar phosphoprotein Nucleophosmin (B23) function for viral replication.

Nucleolar proteins facilitate the replication of certain human and animal viruses through interaction with viral proteins. In this study, an interaction between nervous necrosis virus capsid protein and nucleolar phosphoprotein B23 was identified using in vitro experimental approaches. The capsid protein binds to B23 early during the viral infection and accumulates in the nucleus, particularly in the nucleolus. However, over the course of the infection B23 is redistributed from the nucleoli to the nucleoplasm. siRNA-mediated knockdown of B23 reduced viral replication and cytopathic effect. Thus, B23 targets capsid protein to the nucleus and facilitates NNV replication. The results provide the first demonstration that nucleolar protein B23 has a direct role in the nodavirus replication process.