| Muscovy duck (Cairina moschata) reovirus (DRV) is the causative agent of Muscovy duck Liver white spots disease,a newly recognized Muscovy duck disease of economic importance,characterized by apathy,weak foot.diarrhea and tenosynovitis/viral arthritis.Muscovy duck that recover from infection are markedly stunted in growth.At necropsy,in most cases,liver and spleen are swollen and show small white necrotic foci,kidney is hemorrhagic.During the infection of DRV,young Muscovy ducklings are the most susceptible,the mortality is high. Recently,antigenic variability has been demonstrated among avian reovirus isolates.The S-class genes of the viral genome is the key to research the evolution of avian reovirus in the world ,and two genotypes,i.e.,one genotype which standard strains are DRV-89026 and DRV-89330,the other genotype which standard strain is ARV-S1133.Seven field-isolates were isolated from the liver and spleen with lots of gray-white local necroses of Muscovy ducks in our laboratory,they were identified as DRVs through viral common experimental diagnosis.In order to understand the characteristics of genetic sequences of DRVs in FuJian,nucleotide sequences of the S-class genome segments of DRVs (the field strain YB,the clonal strain YJL and Muscovy duck embryo fibroblast cell passaged strain YH) were examined and analyzed to define phylogenetic profiles and genotype.In this study,one set of oligonucletide primers was designed according to the sequences of the S-class genome segments of American isolate S1133 and 176 and French isolates 89026 and 89330 from Genebank,respectively.3 DRVs were propagated in special antibody negative (SAN) Muscovy duck embryos. The viral RNAs were extracted and used in reverse transcription-polymerase chain reaction (RT-PCR) for amplifying the eight full-length cDNAs of virus genes. The cDNAs were then cloned into pMD18-T vector, and positive plasmids were run on the...
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