Abstract
The complete genomic sequence of a Pekin duck origin reovirus (DRV) from China was determined. The genome comprises 23,419 bp, with segments ranging from 1,191 bp (S4) to 3,959 bp (L1). Pairwise comparisons and phylogenetic analysis indicate that the Pekin duck origin reovirus is more closely related to the new type of Muscovy duck origin reovirus (N-MDRV) identified recently than to the chicken origin avian orthoreovirus (ARV) and the originally described Muscovy duck origin reovirus (ARV-Md).
GENOME ANNOUNCEMENT
Avian orthoreovirus (ARV), one of the five recognized species in the genus Orthoreovirus of the family Reoviridae, has been reported to infect a wide variety of poultry flocks, including chickens, Muscovy ducks, turkeys, and geese (1). Two different reoviruses have been detected in Muscovy ducks: the originally described Muscovy duck reovirus (ARV-Md) (1, 5, 7) and a recently identified new type (or pathotype) of Muscovy duck origin reovirus (N-MDRV) (2, 3, 6).
A recent study involving isolation of a duck reovirus (DRV) marks the emergence of orthoreoviruses capable of causing a fatal disease in Pekin ducklings (4). The disease, known locally as duck spleen necrosis disease, is characterized by one or more large necrotic foci in spleen. To date, only partial nucleotide sequences of σA- and σNS-encoding segments have been determined for the virus (4). To provide more information about this virus, we determined the complete genomic sequence of a DRV (strain 091) which was isolated from a dead Pekin duckling with lesions of spleen necrosis from Jiangsu Province, China, in 2009.
Sequences of the 10 segments were amplified by reverse transcription-PCR (RT-PCR) using primers designed based on the available sequences of the L-, M-, and S-class segments from N-MDRV (6), ARV, and ARV-Md. The termini of the segments were determined by 5′ rapid amplification of cDNA ends protocol.
The DRV 091 genome comprises 23,419 bp, and the sizes of the 10 genome segments are as follows: L1, 3,959 bp; L2, 3,830 bp; L3, 3,907 bp; M1, 2,284 bp; M2, 2,158 bp; M3, 1,996 bp; S1, 1,568 bp; S2, 1,324 bp; S3, 1,202 bp; and S4, 1,191bp. All genome segments are monocistronic and encode one single primary translation product with the exception of S1, which is tricistronic, with three partially overlapping open reading frames (ORFs) encoding p10 (97 amino acids [aa]), a function-unknown protein p18 (162 aa), and σC (321 aa), respectively. The proteins expressed by other 9 genome segments are as follows: λA, 1,293 aa; λB, 1,259 aa; λC, 1285 aa; μA, 732 aa; μB, 675 aa; μNS, 635 aa; σA, 416 aa; σB, 367 aa; and σNS, 367 aa. Pairwise comparisons and phylogenetic analyses indicate that DRV strain 091 is more closely related to N-MDRV than to chicken reoviruses and ARV-Md isolates.
It has been shown that ARV-Md is nonpathogenic for Pekin ducklings (5, 7). However, the pathogenicity of N-MDRV to Pekin ducks remains to be tested. Whether or not DRV and N-MDRV belong to the same virus that may transmit across Pekin ducks and Muscovy ducks is still unclear. Further studies need to be done to address these questions.
Nucleotide sequence accession numbers.
The sequences of the 10 segments of DRV isolate 091 have been deposited in GenBank, with accession numbers ranging from JX478250 (segment L1) to JX478259(segment S4).
ACKNOWLEDGMENTS
This work was supported by the China Agriculture Research System (CARS-43) and Special Fund for Agro-scientific Research in the Public Interest (201003012).
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