Stoltzfus C M, Kuhnert L K
J Virol. 1979 Nov;32(2):536-45. doi: 10.1128/JVI.32.2.536-545.1979.
The polyribosomal fraction from chicken embryo fibroblasts infected with B77 avian sarcoma virus contained 38S, 28S, and 21S virus-specific RNAs in which sequences identical to the 5'-terminal 101 bases of the 38S genome RNA were present. The only polyadenylic acid-containing RNA species with 5' sequences which was detectable in purified virions had a sedimentation coefficient of 38S. This evidence is consistent with the hypothesis that a leader sequence derived from the 5' terminus of the RNA is spliced to the bodies of the 28S and 21S mRNA's, both of which have been shown previously to be derived from the 3' terminal half of the 38S RNA. The entire 101-base 5' terminal sequence of the genome RNA appeared to be present in the majority of the subgenomic intracellular virus-specific mRNA's, as established by several different methods. First, the extent of hybridization of DNA complementary to the 5'-terminal 101 bases of the genome to polyadenylic acid-containing subgenomic RNA was similar to the extent of its hybridization to 38S RNA from infected cells and from purified virions. Second, the fraction of the total cellular polyadenylic acid-containing RNA with 5' sequences was similar to the fraction of RNA containing sequences identical to the extreme 3' terminus of the genome RNA when calculated by the rate of hybridization of the appropriate complementary DNA probes. This suggests that most intracellular virus-specific RNA molecules contain sequences identical to those present in the 5'-terminal 101 bases of the genome. Third, the size of most of the radioactively labeled DNA complementary to the 5'-terminal 101 bases of the genome remained unchanged after the probe was annealed to either intracellular 38S RNA or to various size classes of subgenomic RNA and the hybrids were digested with S1 nuclease and denatured with alkali. However, after this procedure some DNA fragments of lower molecular weight were present. This was not the case when the DNA complementary to the 5'-terminal 101 bases of the genome was annealed to 38S genome RNA. These results suggest that, although the majority of the intracellular RNA contains the entire 101-base 5'-terminal leader sequence, a small population of virus-specific RNAs exist that contain either a shortened 5' leader sequence or additional splicing in the terminal 101 bases.
感染了B77禽肉瘤病毒的鸡胚成纤维细胞的多核糖体组分含有38S、28S和21S病毒特异性RNA，其中存在与38S基因组RNA 5'末端101个碱基相同的序列。在纯化的病毒粒子中可检测到的唯一含有聚腺苷酸且具有5'序列的RNA种类沉降系数为38S。这一证据与以下假设一致，即源自RNA 5'末端的前导序列被剪接到28S和21S mRNA的主体上，这两种mRNA先前已被证明源自38S RNA的3'末端一半。通过几种不同方法确定，基因组RNA的整个101个碱基的5'末端序列似乎存在于大多数亚基因组细胞内病毒特异性mRNA中。首先，与基因组5'末端101个碱基互补的DNA与含聚腺苷酸的亚基因组RNA的杂交程度，与其与感染细胞和纯化病毒粒子的38S RNA的杂交程度相似。其次，当通过适当的互补DNA探针的杂交速率计算时，总细胞含聚腺苷酸RNA中具有5'序列的部分，与含与基因组RNA极端3'末端相同序列的RNA部分相似。这表明大多数细胞内病毒特异性RNA分子含有与基因组5'末端101个碱基中存在的序列相同的序列。第三，与基因组5'末端101个碱基互补的大多数放射性标记DNA在探针与细胞内38S RNA或各种大小类别的亚基因组RNA退火后，其大小保持不变，杂交体用S1核酸酶消化并用碱变性。然而，在此过程后存在一些较低分子量的DNA片段。当与基因组5'末端101个碱基互补的DNA与38S基因组RNA退火时，情况并非如此。这些结果表明，尽管大多数细胞内RNA含有整个101个碱基的5'末端前导序列，但存在一小部分病毒特异性RNA，其含有缩短的5'前导序列或在末端101个碱基中有额外的剪接。
