The UL13 protein of the duck enteritis virus (DEV), predicted to encode a Ser/Thr protein kinase, belongs to the family of conserved herpesvirus protein kinases (CHPK), which plays an important role in herpesvirus proliferation. In this study, truncated UL13 was expressed as a fusion protein of approximately 44 kDa using a prokaryotic expression system, and this protein was used to generate a specific anti-UL13 antibody. This antibody detected UL13 starting at 4 h post infection in duck embryonic fibroblast cells and identified UL13 to be present in both the cytoplasm and the nucleus. UL13 RNA was found to be transcribed starting at 2 h post infection, and the synthesis of the UL13 mRNA was found to be sensitive to the protein synthesis inhibitor cycloheximide (CHX) and tolerant of the DNA polymerase inhibitor ganciclovir (GCV). Its nuclear location and status as an early gene suggested that DEV UL13 might play important roles in DEV replication, which was confirmed by comparing the proliferation of a UL13-knockout mutant virus, a revertant virus, and the parent virus in cell culture. The specific mechanisms of UL13 in viral replication need to be further studied.

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Potato virus Y (PVY) is a serious global virus. At present, PVY are mainly focused on strain analysis and protein interaction with host, but independent studies on PVY replication in vitro are still weak, the main problem is that there is no independent in vitro replication system for PVY. This study was focused on the creation of in vitro replication system mediated by NIb of PVY. The optimal expression concentration of MBP-NIb is 0.2 mM by the IPTG gradient experiment. Based on the solubility analysis, it is suggested that 37℃ is feasible and the soluble ratio of MBP-NIb is about 10%, which is enough for following affinity chromatography against MBP-tag. The purified MBP-NIb can specifically recognize the 3' terminal region of PVY plus or minus strand and perform in vitro replication. This is the first time that an in vitro replication system for PVY has been established. This in vitro replication system will facilitate the study of mechanism on PVY replication.