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.

To detect Salmonella spp. in suspect infected ducks, a loop-mediated isothermal amplification (LAMP) assay was developed. With the help of this assay, we can detect Salmonella enterica serovar Enteriditis and Salmonella enterica serovar Anatis above 6.0 cfu/test and 4.8 cfu/test, respectively, in pure-culture conditions, even in the existence of 0.01 g of duck liver or spleen homogenates; the detection thresholds were still achieved at 6.0 cfu per test tube. Further experiments of the test strains indicated the high specificity of this LAMP assay. In the detection of clinical specimens, a total of 115 Salmonella suspect infected clinical samples was analyzed by traditional culture method, LAMP, and PCR. The results suggested that 11 samples were positive by LAMP and culture methods; however, only 8 specimens were positive by PCR. In consideration of the high sensitivity and fast scanning speed of our LAMP method in clinical specimens, it was more suitable for field application and epidemiological investigation.

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