| Duck hepatitis serotype I is a kind of highly lethal infectious disease caused by duck hepatitis virus serotype I that can make young duck infected. It mainly against within the 4-week-old ducklings,especially less than 1 week ducklings are most easily to infect,the mortality rate may reach 90%. It has become one of the main serious infectious diseases that exist in duck industry. Duck hepatitis was found in the United States the first time in 1945, then the clinical case was reported in Shanghai, China in 1963, and the virus was isolated in 1980. So far, The duck hepatitis virus serotype I spreads widely and speedily. Therefore, it have great significance to conduct a study about the duck hepatitis and the pathogen of the disease. In this study, we took DHV-I strain VFY and strain NFY which were isolated in Fuzhou and preserved in our laboratory as materials, carried out the cloning and sequencing of their complete gene , analysed the amino acid from polyprotein of DHV-I Strain VFY and prognosed the functional sites and the secondary structure of the polypeptide.1. In accordance with the reference of duck hepatitis virus serotype I genome, we designed eight pairs of primers, took the nucleic acid chain of DHV-I local strains VFY and NFY which were isolated in Fuzhou as a template for RT-PCR, then gained the desired objectives of gene fragments. Via nucleic acid sequence splicing we obtain the complete genome of DHV-I strains VFY and NFY.2. We analysed the amino acid polypeptide from open reading frame of DHV-I Strain VFY and prognosed the functional sites and the secondary structure of the polypeptide. The results showed that the polypeptide contains 11 N-glycosylation site, 26 protein kinase C phosphorylation site, 38 casein kinaseⅡphosphorylation site, 32 N-myristoylation site, 4 cAMP-and cGMP-dependent protein kinase phosphorylation site and 2 Tyrosine kinase phosphorylation site. By prediction of the polyprotein secondary structure, it was found that this polyprotein composed of 27.70%α-helical, 23.39%β-pleated sheet, 48.91% Loop or other structures and possesed 2 transmembrane region which are located in 1066-1083 and 1556-1573.3. The results of gene sequencing analysis of DHV-I VFY and NFY showed that: the identity of nucleotide sequence between the two DHV-I and GDZJ strains, 03D strain, A66 strain, JX strains, C80 strains respectively are 97.6%/97.7%, 96.9%/97.0%, 95.4%/95.4%,95.3%/95.4%,95.4%/95.5%.The identity of amino acid sequence respectively are 98.4%/98.4%, 98.2%/98.2%, 97.5% /97.5%, 97.5%/97.5%, 97.6%/97.6%. The identity of nucleotide sequence between DHV-I VFY and NFY is 99.5%, while the identity of amino acid sequence is 98.9%.By gene phylogenetic tree analysis, we know that DHV-I strains VFY and DHV-I strains NFY are in the same branch of the recent genetic relationship. The two strains of DHV-I isolated in Fuzhou and the other DHV-I strains: GDZJ strains, 03D strain, A66 strain, JX strains, C80 strains are in the same small branch indicated that they may have a near genetic relationship. The two DHV-I strains VFY and NFY may have a certain degree of genetic relationship with other domestic DHV-I strains since the identity of nucleotide sequence and amino acid sequence between them are close to each other. But they have far genetic relationship with the new type DHV-I strains which recently isolated in Taiwan and South Korea since their nucleotide homology and amino acid homology is lower. So that the two virus strains may be classified as traditional DHV-I.
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