Characterization of a J domain gene of Spodoptera litura multicapsid nucleopolyhedrovirus

Spodoptera litura multicapsid nucleopolyhedrovirus (SpltMNPV) ORF39 (designated as the bjdp gene) is the only J domain gene recorded in baculovirus genomes to date. Computer-assisted analysis revealed that its deduced amino acid sequences possessed a coiled-coil region and a RNA recognition motif (RRM). In vivo the bdjp gene transcription was detected from 24 h post infection (p.i.) and abundant from 72 to 96 h p.i., while in vitro it was first detected 6 h p.i. and was abundant from 12 to 24 h p.i., respectively. Western blot analysis of BJDP expression with an antiserum made against 6 x His tagged BJDP expressed in Escherichia coli showed that it was present from 24 through 96 h p.i. in vitro. Western blot analysis indicated that BJDP was found to be associated with budded and occlusion-derived virions (ODV). Furthermore, BJDP was shown to be present in both envelope and nucleocapsid fraction of ODV. These results suggested that BJDP might be a structural protein.