Characterization of duck enteritis virus US6, US7 and US8 gene

Duck enteritis virus (DEV) is a member of the family Herpesviridae, the genome of which is not completely analyzed. In order to provide further insights into the genomic organization, we decided to amplify the unknown sequence in the US region since three key glycoproteins are coded in this region. Glycoprotein D encoded by US6 gene is essential for virus entry and plays an important role in protecting animals from lethal challenge. Glycoprotein I and E encoded by US7 and US8 gene are required for cell-to-cell spread.

Single oligonucleotide nested polymerase chain reaction was adopted to amplify the unknown sequence. The open reading frames (ORF) were predicted by Editseq program. Then the sequence was submitted to an online program to search promoter, polyadenylation signal and potential N-glycosylation sites. The phylogenetic analysis was performed by MEGA4.1, while multiple alignments were performed by ClustalX.

Three complete ORFs including US6, US7 and US8 were determined. The three genes shared the same polyadenylation signal. Phylogenetic analysis showed that DEV was closed to mardivirus of alphaherpesvirus.

These results extend our understanding of the DEV genome and its classification, and also provide further basic knowledge for functional investigations on the proteins in the US region.