Research On The Immediate Early Genes Of White Spot Syndrome Virus

White Spot syndrome virus (WSSV) is currently the major viral pathogen ofaquacultured shrimps that causes huge economic losses to shrimp farming industriesworldwide, however, the mechanism of WSSV infection remains unknown.Immediate-early (IE) genes encode regulatory proteins critical for the virus life cycle,therefore, they are keys to understand how virus infect and proliferate in the host cell.In this study, we screened white spot syndrome virus (WSSV) IE genes withcycloheximide (CHX)-treated primary culture of crayfish hemocyte and a WSSVgenome tiling microarray. Sixteen ORFs, including a known WSSV IE gene(ie1/wsv069), were identified and confirmed by RT-PCR and time course studies. The16 identified IE proteins contain four nuclear proteins (WSV051, WSV069, WSV100,WSV079) with transcription activity, one nuclear protein (WSV083) with a Ser/Thrkinase domain and one (WSV249) previously described to function as an ubiqutin E3ligase which was found to locate on the nuclear membrane. Furthermore, most of theidentified WSSV IE genes cluster in a 14 kb genomic region (WSSV China isolate:36,052 to 50,300 bp). This type of arrangement may facilitate the coordinate controland rapid expression of IE genes.Furthermore, promoters of DNA virus immediate early genes are widely used inexpression vectors to drive down stream gene expression. In this study, we alsoanalysed the promoter regulatory regions of WSSV IE genes and identified five strongpromoters including wsv051P, wsv069P, wsv083P, and wsv249P, which couldfunction in insect high-five cells. Moreover, wsv249P was found to drive gene expression in primary cultured crayfish hemocyte as well.