Abstract
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.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Animals
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Bayes Theorem
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Disease Outbreaks
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Ducks
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Evolution, Molecular
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Flavivirus / metabolism*
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Genome, Viral
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Geography
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Glycosylation
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Molecular Sequence Data
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Mutation
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Neutralization Tests
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Phylogeny
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Polymorphism, Genetic
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Poultry
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Poultry Diseases / virology*
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Protein Structure, Tertiary
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Sequence Homology, Amino Acid
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Viral Envelope Proteins / chemistry*
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Viral Envelope Proteins / genetics*
Grants and funding
The study was partially supported by funds from Shandong Provincial Natural Science Foundation (BS2009YY019), Taishan Scholar Program to Institute of Poultry Science, Chinese National Science foundation (31172355/C1806), Agro-scientific research in the public interest (201003012):Rapid diagnosis and vaccine development in major infectious diseases of waterfowl, and the key agricultural program of application technology of Shandong province in 2012: Integrated preventing and controlling technique of Duck Tembusu virus. Works at South Dakota State University (SDSU) were supported in part by the SDSU AES Fund 3AH203 and SD 2010 Research Center (Biological Control and Analysis of Applied Photonics, BCAAP) Fund (3SJ163 to F.L.). Research in the S.C. laboratory was supported by the SDSU AES to S.C. and the South Dakota 2010 Research Center, BCAAP (Biological Control and Analysis of Applied Photonics) Fund (3SG163 to S.C.). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.