Slobodskaya O R, Gmyl A P, Maslova S V, Tolskaya E A, Viktorova E G, Agol V I
M.P. Chumakov Institute of Poliomyelitis and Viral Encephalitides, Russian Academy of Medical Sciences, Moscow Region, Russia.
Virology. 1996 Jul 1;221(1):141-50. doi: 10.1006/viro.1996.0360.
Poliovirus mutants with extended (> 150-nt) deletions in the 5'-untranslated region between the internal ribosome entry site and the initiator codon have been selected previously (Pilipenko et al., Cell 68, 119-131, 1992; Gmyl et al., J. Virol. 67, 6309-6316, 1993). These deletions were transferred into the genome of a mouse-pathogenic poliovirus strain and found to be strongly attenuating. The deletions can be considered as covering three structural elements, a stem-loop (domain E) with a conserved cryptic AUG and two spacers, upstream and downstream of it. In an attempt to identify putative essential determinants of neurovirulence in these individual structural elements, appropriate mutants were engineered. The results demonstrated that neither of the above elements is essential for neurovirulence. The results strongly suggested that the presence of a cryptic AUG in the oligopyrimidine/AUG tandem followed, at a sufficient distance, by the initiator codon was necessary to ensure the neurovirulent phenotype of our constructs. On the other hand, the attenuated phenotype appeared to correlate with the occurrence of the initiator AUG as a moiety of the oligopyrimidine/AUG tandem. Possible mechanisms underlying these effects are discussed. Identification of the cryptic AUG as an essential determinant for neurovirulence provides a rational basis for the design of genetically stable attenuated poliovirus variants.
此前已筛选出脊髓灰质炎病毒突变体，其在内部核糖体进入位点与起始密码子之间的5'-非翻译区存在延伸（> 150个核苷酸）的缺失（Pilipenko等人，《细胞》68卷，119 - 131页，1992年；Gmyl等人，《病毒学杂志》67卷，6309 - 6316页，1993年）。这些缺失被转移到一种小鼠致病性脊髓灰质炎病毒株的基因组中，发现具有很强的减毒作用。这些缺失可被视为覆盖了三个结构元件，一个带有保守隐蔽AUG的茎环（结构域E）以及它上游和下游的两个间隔区。为了确定这些单个结构元件中假定的神经毒力必需决定因素，构建了合适的突变体。结果表明，上述元件均不是神经毒力所必需的。结果强烈提示，在寡嘧啶/AUG串联中存在隐蔽AUG，并在足够距离后紧跟起始密码子，对于确保我们构建体的神经毒力表型是必要的。另一方面，减毒表型似乎与起始AUG作为寡嘧啶/AUG串联的一部分的出现相关。讨论了这些效应背后可能的机制。将隐蔽AUG鉴定为神经毒力的必需决定因素为设计基因稳定的减毒脊髓灰质炎病毒变体提供了合理依据。
