Pöyry T, Kinnunen L, Hovi T
Department of Virology, National Public Health Institute, Helsinki, Finland.
J Virol. 1992 Sep;66(9):5313-9. doi: 10.1128/JVI.66.9.5313-5319.1992.
Poliovirus has a single-stranded RNA genome of about 7,440 nucleotides (nt) with an unusually long 750-nt noncoding region in the 5' end (5'NCR). Several regulatory functions have been assigned to the 5'NCR. We sequenced the 5'NCRs of 33 wild-type 3 poliovirus strains to study the range and distribution of naturally occurring sequence variations. In this regard, the 5'NCR can be divided into a conserved part (nt 1 to 650) and a hypervariable part (nt 651 to 750). In the conserved part, altogether 234 unevenly distributed nucleotide positions (36%) showed variation. When these positions were plotted against the predicted secondary-structure models, it was found that the existence of most of the proposed stem-loop structures was supported by extensive structure-conserving substitutions in the stems. Regions with conserved sequences, as well as mutational hot spots, were observed. The hypervariable part of the 5'NCR varied up to 56% between the strains studied. The A + U percentage was significantly higher than in the conserved part. The number of AUG codons varied between 5 and 15 in the conserved part of the 5'NCR, while none was found in the hypervariable part. These results provide information that can be used in site-directed mutagenesis and other approaches targeted to reveal the functional domains of the 5'NCR.
脊髓灰质炎病毒具有一个约7440个核苷酸（nt）的单链RNA基因组，其5'端（5'NCR）有一个异常长的750 nt非编码区。5'NCR已被赋予多种调控功能。我们对33株野生型3型脊髓灰质炎病毒株的5'NCR进行了测序，以研究自然发生的序列变异的范围和分布。在这方面，5'NCR可分为保守部分（核苷酸1至650）和高变部分（核苷酸651至750）。在保守部分，共有234个分布不均的核苷酸位置（36%）出现变异。当将这些位置与预测的二级结构模型相对应绘制时，发现大多数提出的茎环结构的存在都得到了茎中广泛的结构保守取代的支持。观察到了保守序列区域以及突变热点。所研究的毒株之间，5'NCR的高变部分差异高达56%。A+U百分比显著高于保守部分。5'NCR保守部分的AUG密码子数量在5至15个之间变化，而高变部分未发现AUG密码子。这些结果提供了可用于定点诱变和其他旨在揭示5'NCR功能域的方法的信息。
