Effect of the 5'-untranslated region of pestivirus genome on the host range

黄病毒科的鼠疫病毒属有四个已确定的种；牛病毒性腹泻病毒1 （BVDV-1）、牛病毒性腹泻病毒2 （BVDV-2）、边境病病毒（BDV）和猪瘟病毒（CSFV）以及一个暂定的“长颈鹿”物种。虽然这些病毒种类大多是根据其分离的动物宿主物种来鉴定的，但它们之间存在广泛的抗原交叉反应性，它们可以跨越宿主物种屏障，感染偶蹄动物内部的不同动物物种。血清学数据表明，鼠疫病毒的宿主范围包括大多数偶蹄类动物。鼠疫病毒不仅从家畜中分离出来，而且从鹿或长颈鹿等野生动物中也分离出来。对这些野生动物分离株的分类研究将为鼠疫病毒的生态学和进化提供有用的信息。疫病毒基因组的5′-未翻译区（UTR）在疫病毒属的所有成员中高度保守，因此对物种或基因型的表征很有用。虽然5'-UTR的核苷酸序列在鼠疫病毒属的成员中保守得很好，但已知5'-UTR至少包含三个可变位点。这些可变位点上的核苷酸替换尤其重要，因为正义RNA病毒的5'-UTR通常包含对病毒存活不可或缺的调控基序。因此，5'-UTR的随机突变极有可能与病毒生存不相容。因此，在这一水平上稳定的核苷酸变异在病毒进化史上具有高度的重要性。鼠疫病毒5'-UTR中三个可变位点的核苷酸序列已被证明是回文的，并且能够形成每种鼠疫病毒特有的稳定的茎环结构。为了维持回文序列，茎区经常发生核苷酸替换，从而形成稳定的茎环结构。因此，这种类型的突变被称为回文核苷酸替代（PNS）。根据5′-UTR的PNS，在鼠疫病毒属中区分出5个种（BVDV-1、BVDV-2、CSFV、BDV和“长颈鹿”）。少

The genus Pestivirus of the family Flaviviridae is represented by four established species ; Bovine viral diarrhea virus 1 (BVDV-1), Bovine viral diarrhea virus 2 (BVDV-2), Border disease virus (BDV) and Classical swine fever virus (CSFV) and a tentative "Giraffe" species. Although these viral species are identified mostly according to the animal host species from which they are isolated, there is an extensive antigenic cross reactivity among them, and they can cross the host species barrier and infect different animal species within the cloven-footed animals. Serological data indicate that the host range of pestiviruses includes most even-toed ungulates. Pestiviruses have been isolated not only from domestic animals but also from wildlife, such as deer or giraffe. Taxonomic study on these isolates from wildlife will provide useful information on the ecology and evolution of pestiviruses. The 5'-untranslated region (UTR) of pestivirus genome is highly conserved among all members within … More the genus Pestivirus, thus being useful for the characterization of species or genotypes. Although the nucleotide sequence of the 5'-UTR is well conserved among the members of the Pestivirus genus, the 5'-UTR has been known to contain at least three variable loci. The nucleotide substitutions at these variable loci are particularly important because the 5'-UTR of positive-sense RNA viruses generally includes regulatory motifs, which are indispensable to viral survival. Therefore, random mutations at the 5'-UTR have a high probability of incompatibility with viral survival. Thus stable nucleotide variations at this level assume high importance in terms of virus evolutionary history. Nucleotide sequences at the three variable loci in the 5'-UTR of pestiviruses have been shown to be palindromic and capable of forming a stable stem-loop structure peculiar to each Pestivirus species. Nucleotide substitutions in the stem regions always occur to maintain the palindromic sequence and thereby form a stable stem-loop structure. Thus, this type of mutation was referred to palindromic nucleotide substitutions (PNS). On the basis of the PNS at the 5'-UTR, five species (BVDV-1, BVDV-2, CSFV, BDV and "Giraffe") were distingushed in the genus Pestivirus. Less