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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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Bayesian phylogenetic tree of viral E proteins.The six strains of DTMUV we sequenced were marked with purple background. The Bayesian posterior probabilities were labeled on each node (1, high confident branching; 0, low confident branching). The bottom scale bar represents divergence time (unit: year).
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pone-0071319-g005: Bayesian phylogenetic tree of viral E proteins.The six strains of DTMUV we sequenced were marked with purple background. The Bayesian posterior probabilities were labeled on each node (1, high confident branching; 0, low confident branching). The bottom scale bar represents divergence time (unit: year).

Mentions: A phylogenetic tree was inferred from the nucleotide sequences of E proteins (Fig. 5). Overall, two main clusters were observed with Bayesian posterior probability support of 1. One consisted of Bagaza virus and JEV, the other included Tembusu virus, Sitiawan virus and DTMUV. The phylogenetic closeness of DTMUV to the Tembusu and Sitiawan viruses is consistent with results of previous studies [1], [2], [4], [5]. With the exception of one outlier, all DTMUV isolates were clustered into the two clearly defined genotypes (DTMUV.I and DTMUV.II). Interestingly, DTMUV.I had only four strains and all of them were isolated in the 2010 epidemic. DTMUV.II contained sixteen members that were isolated from 2010 to 2012 epidemics. DTMUV.II was further clustered into two subgroups (DTMUV.II.a and DTMUV.II.b), although the posterior probability support was not high (0.64). Both DTMUV.II.a and DTMUV.II.b contained virus isolates ranging from 2010 to 2012. Three of the six viruses we isolated were in group DTMUV.I (BZ_2010, LD_2010 and LC_2010), two in subgroup DTMUV.II.a (GX_2011 and WFZ_2012) and one in subgroup DTMUV.II.b (FX_2012). In summary, our phylogenetic analysis showed that this new duck flavivirus was closely related to Tembusu and Sitiwan viruses. The results also provided preliminary evidence that currently circulating DTMUV strains likely evolved into two independent genetic subgroups. Finally, we estimated the evolutionary rate of this emerging virus. Our data indicated that the estimated substitution rate for DTMUV was about 5×10−4 nucleotides per site per year (Fig. S1). This estimation was similar to those reported previously for influenza A viruses [22], indicating that this new pathogen evolved with a relative fast rate.


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)

Bayesian phylogenetic tree of viral E proteins.The six strains of DTMUV we sequenced were marked with purple background. The Bayesian posterior probabilities were labeled on each node (1, high confident branching; 0, low confident branching). The bottom scale bar represents divergence time (unit: year).
© Copyright Policy
Related In: Results  -  Collection

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

pone-0071319-g005: Bayesian phylogenetic tree of viral E proteins.The six strains of DTMUV we sequenced were marked with purple background. The Bayesian posterior probabilities were labeled on each node (1, high confident branching; 0, low confident branching). The bottom scale bar represents divergence time (unit: year).
Mentions: A phylogenetic tree was inferred from the nucleotide sequences of E proteins (Fig. 5). Overall, two main clusters were observed with Bayesian posterior probability support of 1. One consisted of Bagaza virus and JEV, the other included Tembusu virus, Sitiawan virus and DTMUV. The phylogenetic closeness of DTMUV to the Tembusu and Sitiawan viruses is consistent with results of previous studies [1], [2], [4], [5]. With the exception of one outlier, all DTMUV isolates were clustered into the two clearly defined genotypes (DTMUV.I and DTMUV.II). Interestingly, DTMUV.I had only four strains and all of them were isolated in the 2010 epidemic. DTMUV.II contained sixteen members that were isolated from 2010 to 2012 epidemics. DTMUV.II was further clustered into two subgroups (DTMUV.II.a and DTMUV.II.b), although the posterior probability support was not high (0.64). Both DTMUV.II.a and DTMUV.II.b contained virus isolates ranging from 2010 to 2012. Three of the six viruses we isolated were in group DTMUV.I (BZ_2010, LD_2010 and LC_2010), two in subgroup DTMUV.II.a (GX_2011 and WFZ_2012) and one in subgroup DTMUV.II.b (FX_2012). In summary, our phylogenetic analysis showed that this new duck flavivirus was closely related to Tembusu and Sitiwan viruses. The results also provided preliminary evidence that currently circulating DTMUV strains likely evolved into two independent genetic subgroups. Finally, we estimated the evolutionary rate of this emerging virus. Our data indicated that the estimated substitution rate for DTMUV was about 5×10−4 nucleotides per site per year (Fig. S1). This estimation was similar to those reported previously for influenza A viruses [22], indicating that this new pathogen evolved with a relative fast rate.

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