Monceyron C, Grinde B, Jonassen T O
Department of Virology, National Institute of Public Health, Oslo, Norway.
Arch Virol. 1997;142(4):699-706. doi: 10.1007/s007050050112.
We have sequenced the 3'-end of the RNA genomes of 14 serotyped and 12 untyped isolates of human astrovirus. The sequences, which include all 8 serotypes, were used to predict secondary structures, postulate possible functional domains, reveal conserved regions suitable for nucleic acid amplification and perform phylogenetic analysis. The final nucleotides of the capsid protein precursor gene and the adjacent 3'-noncoding region were highly conserved and, except for 35 nucleotides with homology to a sequence in the 3'-end of a coronavirus RNA genome, unique to astrovirus family. This confirms that the 3'-end is a suitable target for universal and specific detection of astrovirus RNA. For the deduced 72 C-terminal amino acids of the capsid protein precursor, distances between the serotypes were found to vary from 0.1 substitution per site between serotypes 3 and 7 to more than one substitution per site between serotype 4 and the other serotypes. Different isolates of the same serotype were closely related, which indicates that the presently used type-specific antibodies differentiate between phylogenetically distinct groups. RNA secondary structures with minimal free energy were predicted using computer programs. Comparative sequence analysis verified the significance of certain of the predicted structural elements.
我们对14株血清分型的和12株未分型的人星状病毒RNA基因组的3'末端进行了测序。这些序列涵盖了所有8种血清型，用于预测二级结构、推测可能的功能域、揭示适合核酸扩增的保守区域并进行系统发育分析。衣壳蛋白前体基因的最后核苷酸及相邻的3'非编码区高度保守，除了与冠状病毒RNA基因组3'末端一个序列有同源性的35个核苷酸外，是星状病毒科所特有的。这证实了3'末端是星状病毒RNA通用和特异性检测的合适靶标。对于衣壳蛋白前体推导的72个C末端氨基酸，发现血清型之间的位点替换距离从血清型3和7之间的每个位点0.1个替换到血清型4与其他血清型之间的每个位点超过1个替换不等。同一血清型的不同分离株密切相关，这表明目前使用的型特异性抗体可区分系统发育上不同的组。使用计算机程序预测了具有最小自由能的RNA二级结构。比较序列分析证实了某些预测结构元件的重要性。
