[Genomic sequence of a new serotype duck hepatitis virus]

A strain of highly pathogenic duck hepatitis virus was isolated in south China from a Pekin duck flock in 1999. No cross reaction with type 1 and 3 duck hepatitis virus was found by serum neutralization. We suggested the strain should be classified as a new serotype of duck hepatitis virus and named it as DHV-N G strain in our previous study. We wanted to reveal the evolution of this virus in molecular level and gene sequence differences between it and DHV-1 strains.

We used RT-PCR and 5'-/3'-RACE to amplify the complete genome sequence of DHV-N G strain and compared it with other picornaviruses.

The genome of DHV-N G consists of 7774 nucleotides excluding a poly (A) tail of 12 nucleotides. It contains a single large open reading frame encoding a polypeptide of 2251 amino acid residues. The length of 3' UTR of DHV-N G is 366 nucleotides, which is 52 nucleotides longer than that of DHV-1 C80 strain. Significant amino acid variation was found in the protein VP1, especially at the position of 140 - 221 comparing with DHV-1. The DHV-N G genome shares 72.8% - 73.4%, 96.3% - 96.5% and 78.3% similarity with DHV-1 strains, Korea's and Taiwanese DHV-N strains, respectively.

The genome structure of DHV-N G strain is obviously different with that of DHV-1 strains. The homologies of genome among the DHV-N group are variable, therein DHV-N G strain is more homologous with Korea's strains than with Taiwanese.