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Structural, antigenic, and evolutionary characterizations of the envelope protein of newly emerging Duck Tembusu Virus.

Yu K, Sheng ZZ, Huang B, Ma X, Li Y, Yuan X, Qin Z, Wang D, Chakravarty S, Li F, Song M, Sun H - PLoS ONE (2013)

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: College of Veterinary Medicine, Yangzhou University, Yangzhou, China ; Institute of Poultry Science, Shandong Academy of Agricultural Sciences, Jinan, China.

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.

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Related in: MedlinePlus

Multiple sequence alignment of the E proteins.The predicted glycosylation sites were marked with star underneath the alignment. Conserved histidines at E protein oligomerization interfaces were labeled with blue circle while histidines conserved in DTMUV and JEV viruses were labeled with magenta circle. The diagram of secondary structure was determined according to the modeled structure of E protein of FX-2012 strain and shown underneath the sequence alignment (rectangle, helix; arrow, β strand). Transmembrane helixes were predicted with TMHMM. Color scheme for sequence alignment position: positive charged amino acids: red; negative charged amino acids, magenta; polar amino acids, green; hydrophobic amino acids, blue. Less conserved positions were colored with lighter color of the corresponding amino acid category. Color scheme for secondary structure: orange, domain I; green, domain II; blue, domain III; red, transmembrane helix.
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pone-0071319-g003: Multiple sequence alignment of the E proteins.The predicted glycosylation sites were marked with star underneath the alignment. Conserved histidines at E protein oligomerization interfaces were labeled with blue circle while histidines conserved in DTMUV and JEV viruses were labeled with magenta circle. The diagram of secondary structure was determined according to the modeled structure of E protein of FX-2012 strain and shown underneath the sequence alignment (rectangle, helix; arrow, β strand). Transmembrane helixes were predicted with TMHMM. Color scheme for sequence alignment position: positive charged amino acids: red; negative charged amino acids, magenta; polar amino acids, green; hydrophobic amino acids, blue. Less conserved positions were colored with lighter color of the corresponding amino acid category. Color scheme for secondary structure: orange, domain I; green, domain II; blue, domain III; red, transmembrane helix.

Mentions: Multiple sequence alignment demonstrated that six E proteins shared approximately 98% identity (data not shown) and only thirteen positions of the E protein were shown to exhibit genetic polymorphisms (Figs. 2 and 3). To map structurally these mutations in E proteins of six viruses, we took advantage of the recently resolved crystal structure of the E protein of a Japanese Encephalitis virus (JEV) [10], a mosquito-borne zoonotic flavivirus, which has about 65% sequence identity with DTMUV E protein. The relatively high protein identity should allow us to establish a reliable model of DTMUV E protein that can be used to predict its important structural features.


Structural, antigenic, and evolutionary characterizations of the envelope protein of newly emerging Duck Tembusu Virus.

Yu K, Sheng ZZ, Huang B, Ma X, Li Y, Yuan X, Qin Z, Wang D, Chakravarty S, Li F, Song M, Sun H - PLoS ONE (2013)

Multiple sequence alignment of the E proteins.The predicted glycosylation sites were marked with star underneath the alignment. Conserved histidines at E protein oligomerization interfaces were labeled with blue circle while histidines conserved in DTMUV and JEV viruses were labeled with magenta circle. The diagram of secondary structure was determined according to the modeled structure of E protein of FX-2012 strain and shown underneath the sequence alignment (rectangle, helix; arrow, β strand). Transmembrane helixes were predicted with TMHMM. Color scheme for sequence alignment position: positive charged amino acids: red; negative charged amino acids, magenta; polar amino acids, green; hydrophobic amino acids, blue. Less conserved positions were colored with lighter color of the corresponding amino acid category. Color scheme for secondary structure: orange, domain I; green, domain II; blue, domain III; red, transmembrane helix.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3750017&req=5

pone-0071319-g003: Multiple sequence alignment of the E proteins.The predicted glycosylation sites were marked with star underneath the alignment. Conserved histidines at E protein oligomerization interfaces were labeled with blue circle while histidines conserved in DTMUV and JEV viruses were labeled with magenta circle. The diagram of secondary structure was determined according to the modeled structure of E protein of FX-2012 strain and shown underneath the sequence alignment (rectangle, helix; arrow, β strand). Transmembrane helixes were predicted with TMHMM. Color scheme for sequence alignment position: positive charged amino acids: red; negative charged amino acids, magenta; polar amino acids, green; hydrophobic amino acids, blue. Less conserved positions were colored with lighter color of the corresponding amino acid category. Color scheme for secondary structure: orange, domain I; green, domain II; blue, domain III; red, transmembrane helix.
Mentions: Multiple sequence alignment demonstrated that six E proteins shared approximately 98% identity (data not shown) and only thirteen positions of the E protein were shown to exhibit genetic polymorphisms (Figs. 2 and 3). To map structurally these mutations in E proteins of six viruses, we took advantage of the recently resolved crystal structure of the E protein of a Japanese Encephalitis virus (JEV) [10], a mosquito-borne zoonotic flavivirus, which has about 65% sequence identity with DTMUV E protein. The relatively high protein identity should allow us to establish a reliable model of DTMUV E protein that can be used to predict its important structural features.

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: College of Veterinary Medicine, Yangzhou University, Yangzhou, China ; Institute of Poultry Science, Shandong Academy of Agricultural Sciences, Jinan, China.

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.

Show MeSH
Related in: MedlinePlus