Identification and molecular analysis of the highly pathogenic duck hepatitis virus type 1 in Hubei province of China.

Duck hepatitis virus types 1 (DHV-1) JX strain was isolated from infected ducklings with clinical symptoms from Hubei province of China. These isolated strains showed high pathogenicity to both duck embryo and duckling in Duck embryo neutralization assay and animal infection experiment. The complete genome of JX strain was sequenced. Comparative genome analysis with other available strains in GenBank indicated that JX strain shared 94-99% similarity at the nucleotide level and 95-99% at amino acid level with other DHV-1 strains. Sequence results showed that mutations of nucleotide and amino acid were mainly distributed in VP1 genes. Our result implied that the VP1 probably was the major virulent determinant of DHV-1. In addition, 13 DHV-1 strains from different area were analyzed in phylogeny and they can be grouped into four distinct lineages. The new-identified JX strain was grouped into one lineage with A66 and C80 strains, which were also isolated from China.