A so called "new duck disease" with the character of necrosis of spleen and pancreas broke out in flocks of muscovy ducks at the end of 1999 in Zhejiang province. Viruses with different conformation and size, one of which was similar to reovirus were found under electronic microscope in allantoic fluid for virus isolation. Three pairs of primers were designed and synthesized based on the published S1 sequences of muscovy duck reovirus (mDRV). Specific RT-PCR products were obtained from both diseased tissues and allantoic fluid for virus isolation. Cloning and sequencing of the fragment and BLAST analysis result further verified the existence and participation of mDRV in the disease. A 1 260 bp S1 full-length sequence of the virus (ZJ99) was further amplified and sequenced. Phylogenic analysis result based on S1 sequences showed that the ZJ99 was in the same group with mDRVs of the French strain and the Fujian strain, while it had some distance to the group of the chicken reoviruses and was far more distant to that of mammalian. On the other hand, the nucleotide sequence of S1 of the ZJ99 strain had a homology of 98% with that of Fujian strain (300 bp partial sequence), while only had 90% homology to that of French strain. It was speculated that mDRVs isolated from different area of China, which had some differences with French strains, were the same strain but spreading in different area.
