Research Note: Duck plague virus pUL48 is a late protein that plays an important role in viral replication.

Duck plague virus (DPV) pUL48 is a homologous of herpes simplex virus VP16, and some studies have shown that VP16 is essential for viral replication and proliferation, but there are few studies on DPV pUL48. Therefore, in order to study the function of pUL48 protein, we constructed a UL48-deleted mutant (DPV-BAC-∆UL48) that completely reemoved the UL48 gene from the DPV BAC genome and the revertant virus (DPV-BAC-∆UL48R) by using the 2-step red recombination system. Compared with the parental virus (DPV-BAC) and the revertant virus, the titer of UL48-deleted mutant was reduced by more than 38.2%, and the efficiency of producing infectious virions was significantly reduced. In addition, the average size of plaques produced by UL48-deleted mutant was about 30% smaller than that of the parental and revertant viruses, suggesting that pUL48 protein affected the cell-to-cell transmission of DPV. Finally, pharmacological inhibition assay showed that pUL48 is a late protein of DPV. In this study, we found that UL48, as a late gene, plays an important role in viral replication by affecting the formation of DPV infectious virion, virus cell-to-cell transmission, and viral genome transcription, which may provide some help for the study of the function of DPV pUL48 protein and the prevention and control of DPV.