Kaneko S, Miller R H
Hepatitis Viruses Section, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland 20892.
J Virol. 1988 Nov;62(11):3979-84. doi: 10.1128/JVI.62.11.3979-3984.1988.
In vitro gene expression systems for hepatitis B virus have demonstrated that the virus genome is capable of producing an X-region-specific transcript of approximately 0.7 kilobases (kb). However, this transcript has not been detected in virus-infected cells. We now report the presence of a heterogeneous X-region-specific transcript of approximately 0.65 kb that is found primarily in the nucleus of liver cells infected with the woodchuck hepatitis virus. Interestingly, the majority of the transcripts are not polyadenylated. The transcript, which represents less than 1% of total virus-specific RNA, is found in animals with both acute and chronic woodchuck hepatitis virus infections. While it is probable that the 0.65-kb transcript is involved in the expression of the X gene protein, it may also direct the translation of a protein encoded by a newly identified open reading frame, ORF5, that is present in all hepadnavirus genomes analyzed.
针对乙型肝炎病毒的体外基因表达系统已证明，该病毒基因组能够产生一种大小约为0.7千碱基（kb）的X区域特异性转录本。然而，在病毒感染的细胞中尚未检测到这种转录本。我们现在报告发现了一种大小约为0.65 kb的异质性X区域特异性转录本，主要存在于感染土拨鼠肝炎病毒的肝细胞的细胞核中。有趣的是，大多数转录本没有多聚腺苷酸化。这种转录本在急性和慢性土拨鼠肝炎病毒感染的动物中均有发现，占病毒特异性RNA总量的比例不到1%。虽然0.65 kb的转录本可能参与X基因蛋白的表达，但它也可能指导一种由新鉴定的开放阅读框ORF5编码的蛋白质的翻译，该开放阅读框存在于所有已分析的嗜肝DNA病毒基因组中。
