Jeng K S, Su P Y, Lai M M
Howard Hughes Medical Institute and Department of Molecular Microbiology and Immunology, University of Southern California School of Medicine, Los Angeles, California 90033-1054, USA.
J Virol. 1996 Jul;70(7):4205-9. doi: 10.1128/JVI.70.7.4205-4209.1996.
The mechanism of regulation for the ribozyme activity of hepatitis delta virus (HDV) RNA in infected cells is unknown. Previously, we developed a direct assay capable of detecting the ribozyme activity of HDV dimer or trimer RNAs in vivo (K.-S. Jeng, A. Daniel, and M. M. C. Lai, J. Virol, 70:2403-2410, 1996). In this study, we used this method to examine the effects of hepatitis delta antigen (HDAg) on the ribozyme activities of HDV RNA in vivo. The HDV multimer cDNAs were cotransfected with plasmids encoding either HDV small delta antigen (SHDAg) or large delta antigen (LHDAg), and the self-cleavage of the primary transcripts from the HDV cDNA was analyzed at day 2 postransfection. The results were as follows. (i) Both HDAgs, particularly LHDAg, enhanced the self-cleavage activity of HDV RNA; however, HDAgs are not required for HDV RNA cleavage. (ii) HDAg could not restore the ribozyme activity of mutant HDV RNAs which have lost the ribozyme function. (iii) The enhancement of ribozyme activity by HDAg does not require HDV RNA replication. (iv) RNA-binding activity of HDAg is required for the enhancement of RNA cleavage. (v) The self-ligation activities of HDV ribozyme also were enhanced by HDAg. These results suggest that HDAg can regulate the cleavage and ligation of HDV RNA during the HDV life cycle.
丁型肝炎病毒（HDV）RNA在受感染细胞中的核酶活性调控机制尚不清楚。此前，我们开发了一种直接检测方法，能够在体内检测HDV二聚体或三聚体RNA的核酶活性（K.-S. Jeng、A. Daniel和M. M. C. Lai，《病毒学杂志》，70:2403 - 2410，1996）。在本研究中，我们使用该方法检测了丁型肝炎抗原（HDAg）对体内HDV RNA核酶活性的影响。将HDV多聚体cDNA与编码HDV小δ抗原（SHDAg）或大δ抗原（LHDAg）的质粒共转染，并在转染后第2天分析HDV cDNA初级转录本的自我切割情况。结果如下：（i）两种HDAg，尤其是LHDAg，增强了HDV RNA的自我切割活性；然而，HDV RNA切割并不需要HDAg。（ii）HDAg不能恢复已丧失核酶功能的突变HDV RNA的核酶活性。（iii）HDAg对核酶活性的增强不需要HDV RNA复制。（iv）HDAg的RNA结合活性是增强RNA切割所必需的。（v）HDAg也增强了HDV核酶的自我连接活性。这些结果表明，HDAg可在HDV生命周期中调节HDV RNA的切割和连接。
