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Outbreaks of duck Tembusu virus (DTMUV) have caused substantial economic losses in the major duck-producing regions of China since 2010. To improve our understanding of the host cellular responses to virus infection and the pathogenesis of DTMUV infection, we applied isobaric tags for relative and absolute quantification (iTRAQ) labeling coupled with multidimensional liquid chromatography-tandem mass spectrometry to detect the protein changes in duck embryo fibroblast cells (DEFs) infected and mock-infected with DTMUV. In total, 434 cellular proteins were differentially expressed, among which 116, 76, and 339 proteins were differentially expressed in the DTMUV-infected DEFs at 12, 24, and 42 hours postinfection, respectively. The Gene Ontology analysis indicated that the biological processes of the differentially expressed proteins were primarily related to cellular processes, metabolic processes, biological regulation, response to stimulus, and cellular organismal processes and that the molecular functions in which the differentially expressed proteins were mainly involved were binding and catalytic activity. Some selected proteins that were found to be differentially expressed in DTMUV-infected DEFs were further confirmed by real-time PCR. The results of this study provide valuable insight into DTMUV-host interactions. This could lead to a better understanding of DTMUV infection mechanisms.

The genomic sequence of a strain of duck enteritis virus (DEV) was determined and analyzed in this study. The size of its genome is 158,091 bp in length and the genome is predicted to encode 78 putative proteins and resembles the members of the Alphaherpesvirinae in genomic organization and gene composition. The genome of the virus is composed of a unique long (UL) region, a unique short (US) region, a unique short internal repeat (IRS) region and a unique short terminal repeat (TRS) region. Its genomic arrangement pattern (UL-IRS-US-TRS) corresponds to D-type herpesvirus and is consistent with the members of Varicellovirus and Iltovirus genera. Sequence analysis reveals that the genome of the virus contains 67 genes having homologs in most members of the Alphaherpesvirinae. Out of these genes, one gene has a homolog in cercopithecine herpesvirus 8 which is a virus of Betaherpesvirinae, and 5 genes have homologs in avian herpesviruses. Furthermore, the genome possesses three unique genes without homologs in any other herpesviruses. Like most members of the Alphaherpesvirinae, the genes in the UL region of its genome are well conserved, whereas the gene arrangement of IRS-US is similar to that of Marek's disease virus and equine herpesviruses 1. Therefore, our data based on the genomic analysis suggest that DEV represents an osculant taxonomic entity within the Alphaherpesvirinae.

Since the first reported cases of ducks infected with a previously unknown flavivirus in eastern China in April 2010, the virus, provisionally designated Duck Tembusu Virus (DTMUV), has spread widely in domestic ducks in China and caused significant economic losses to poultry industry. In this study, we examined in detail structural, antigenic, and evolutionary properties of envelope (E) proteins of six DTMUV isolates spanning 2010–2012, each being isolated from individual farms with different geographical locations where disease outbreaks were documented. Structural analysis showed that E proteins of DTMUV and its closely related flavivirus (Japanese Encephalitis Virus) shared a conserved array of predicted functional domains and motifs. Among the six DTMUV strains, mutations were observed only at thirteen amino acid positions across three separate domains of the E protein. Interestingly, these genetic polymorphisms resulted in no detectable change in viral neutralization properties as demonstrated in a serum neutralization assay. Furthermore, phylogenetic analysis of the nucleotide sequences of the E proteins showed that viruses evolved into two distinct genotypes, termed as DTMUV.I and DTMUV.II, with II emerging as the dominant genotype. New findings described here shall give insights into the antigenicity and evolution of this new pathogen and provide guidance for further functional studies of the E protein for which no effective vaccine has yet been developed. [ABSTRACT FROM AUTHOR]