Cloning and Sequence Analysis of Duch Hepatitis B virus Genome from Hubei Brown Ducks
Abstract: Seventy serum samples were collected from adult brown ducks in Hubei were collected in order to clarify the natural Duck hepatitis B virus (DHBV) infection in and to characterize the genome structure of DHBV. The complete genome of the DHBV strain was amplified by polymerase chain reaction (PCR) and cloned into T vector and sequenced. The results showed that the natural infection rate of DHBV in Hubei was 10%. The DHBV genome isolated by PCR (GenBank accession number DQ276978 ) had 3 024 nucleotides with three overlapping reading frames encoding the surface, core and the polymerase proteins, respectively. Comparison of genome sequences of this strain with those of 17 DHBV strains from the GenBank revealed an identity from 89.3% to 93.5% at the nucleotide level. The amino acid sequences of the S protein，core protein，and functional domain of the Pol protein were highly reserved among all of these DHBV strains. This Hubei strain was found to share more signature amino acids in the polymerase genes with the “Chinese” DHBV strains than those of the “Western” country strains. This finding was also corroborated by a phylogenetic tree analysis. Therefore, this Hubei DHBV strain should be classified to a subtype of the Chinese strains.