Investigation of nervous necrosis virus (NNV) replication in vitro using RNA in situ hybridization.

•Viral segments RNA1 and RNA2 were localized in NNV-infected cells by ISH using labeled RNA probes.•RNA1 and RNA2 was expressed at an early stage, virions are then assembled through the initially expressed viral genes.•The RNA1 gene was expressed separately by double labeling RNA-ISH.•Although the packaging of infectious particles is efficient, the RNA1 gene was still over-produced.