鸭肝炎病毒新血清型基因组序列分析

Genomic sequence of a new serotype duck hepatitis virus

【目的】为了揭示鸭肝炎病毒新血清型(DHV-N)G株的演化及其与DHV-1的基因序列差异。【方法】运用RT-PCR结合5′-/3′-RACE策略对DHV-NG株基因组进行扩增,克隆测序后进行序列分析。【结果】DHV-NG株全基因组序列除12ntpoly(A)尾外全长共7774nt,含有一个大的开放阅读框,编码2251aa的蛋白前体,其基因组结构:5′UTR-L-VP0-VP3-VP1-2A1-2A2-2B-2C-3A-3B-3C-3D-3′UTR;3′UTR长为366nt,比1型鸭肝炎病毒C80株多52nt;VP1蛋白与DHV-1相比发生较大的变异,特别在其第140～221位;其基因组与DHV-1、韩国DHV-N和台湾DHV-N的同源率分别为72.8%～73.4%、96.3%～96.5%和78.3%。【结论】DHV-NG株基因组结构与DHV-1存在明显差异,在DHV-N成员DHV-NG株与韩国DHV-N关系更为密切。

[Objective] 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. [ Methods] 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. [Results] 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 Taiwan Residents DHV-N strains, respectively. [ Conclusion] 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 Taiwan Residents.