Sharmeen L, Kuo M Y, Dinter-Gottlieb G, Taylor J
Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111.
J Virol. 1988 Aug;62(8):2674-9. doi: 10.1128/JVI.62.8.2674-2679.1988.
The structure and replication of the single-stranded circular RNA genome of hepatitis delta virus (HDV) are unique relative to those of known animal viruses, and yet there are real similarities between HDV and certain infectious RNAs of plants. Therefore, since some of the latter RNAs have been shown to undergo in vitro site-specific cleavage and even ligation, we tested the hypothesis that similar events might also occur for HDV RNA. In partial confirmation of this hypothesis, we found that in vitro the RNA complementary to the HDV genome, the antigenomic RNA, could undergo a self-cleavage that was not only more than 90% efficient but also occurred only at a single location. This cleavage was found to produce junction fragments consistent with a 5'-hydroxyl and a cyclic 2',3'-monophosphate. Since the observed cleavage was both site-specific and occurred only once per genome length, we propose that the site may be relevant to the normal intracellular replication of the HDV genome. Because the site is located almost adjacent to the 3' end of the delta antigen-coding region, the only known functional open reading frame of HDV, we suggest that the cleavage may have a role not only in genome replication but also in RNA processing, helping to produce a functional mRNA for the translation of delta antigen.
丁型肝炎病毒（HDV）的单链环状RNA基因组的结构和复制相对于已知动物病毒而言是独特的，然而HDV与某些植物感染性RNA之间确实存在相似之处。因此，鉴于一些后者的RNA已被证明在体外会发生位点特异性切割甚至连接，我们测试了HDV RNA可能也会发生类似事件的假设。部分证实这一假设的是，我们发现体外与HDV基因组互补的RNA，即反基因组RNA，能够进行自我切割，其效率不仅超过90%，而且仅在单个位置发生。发现这种切割产生的连接片段与5'-羟基和环状2',3'-单磷酸一致。由于观察到的切割既是位点特异性的，并且每个基因组长度仅发生一次，我们提出该位点可能与HDV基因组的正常细胞内复制有关。因为该位点几乎位于δ抗原编码区（HDV唯一已知的功能性开放阅读框）的3'端附近，我们认为这种切割不仅可能在基因组复制中起作用，还可能在RNA加工中起作用，有助于产生用于δ抗原翻译的功能性mRNA。
