Origin and evolution of viruses causing classical swine fever in Cuba
Origin and evolution of viruses causing classical swine fever in Cuba
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DOI：
10.1016/j.virusres.2005.03.018
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发表时间：
2005-09-01
期刊：
影响因子：
5
通讯作者：
Núñez, JI
中科院分区：
文献类型：
--
作者：
de Arce, HD;Ganges, L;Núñez, JI
我们通过对 E2 糖蛋白和 NS5B（聚合酶）基因内的区域进行核苷酸测序，分析了自 2001 年以来影响古巴的猪瘟 (CSF) 病毒的起源和进化。确定了在岛上不同地点分离的 10 种 CSF 病毒的 E2 基因 190 个核苷酸的序列，并用于系统发育分析，包括先前确定的 1993-1997 年流行病病毒的序列，以及来自不同 CSFV 基因型代表的序列。获得的系统发育树表明，目前流行的病毒属于1.2亚组，与1993-1997年动物流行期间分离的病毒密切相关，包括用于古巴疫苗效力测试的玛格丽塔毒株。然而，这些分析揭示的进化模式与之前观察到的不同，其中西部分离株与玛格丽塔菌株几乎相同，而东部分离株则表现出更高水平的遗传多样性。在这种情况下，所有分析的病毒都分组在一个独立的、定义的簇中，该簇与先前在古巴西部传播的玛格丽塔相关病毒密切相关，但又有所区别。此外，2001-2003 年病毒显示出分支模式，其序列多样化水平与东部 1993-1997 年病毒中观察到的相似。有趣的是，E2 序列中发现的突变中有很大一部分（约 54%）导致氨基酸替换。这种高比率的非同义突变在之前的古巴流行病中没有发现，也没有在其他脑脊液疫情中报告过。尽管进行了这些氨基酸替换，但不同分离株与 CSFV 特异性单克隆抗体和多克隆血清的反应性没有观察到抗原变化。 7个分离株和Margarita菌株NS5B基因409个核苷酸的系统发育树与E2序列得到的系统发育树一致。在这个编码非结构蛋白的区域中，观察到非同义突变的固定水平较低。获得的结果表明，在古巴当前的动物流行期间，影响猪瘟病毒传播的流行病学因素可能有利于E2基因中非同义突变的固定，这可能与大多数受影响动物出现的临床症状的严重程度较低有关。 (c) 2005 年 Elsevier B.V. 出版
We have analyzed the origin and evolution of viruses from the classical swine fever (CSF) epidemic that affects Cuba since 2001 by nucleotide sequencing of regions within the E2 glycoprotein and the NS5B (polymerase) genes. The sequence of 190 nucleotides from E2 gene was determined for 10 CSF viruses isolated at different locations of the island, and used for phylogenefic analyses, including sequences from viruses of the 1993-1997 epizootic, previously determined, as well as those from representatives of the different CSFV genotypes. The phylogenetic tree obtained indicates that viruses circulating at present belong to the subgroup 1.2 and are closely related to those isolated during the 1993-1997 epizootic, including the strain Margarita used for vaccine potency tests in Cuba. However, the pattern of evolution revealed by these analyses was different than that observed previously, in which western isolates were almost identical to Margarita strain, while eastern isolates showed a higher level of genetic diversification. In this case, all the viruses analyzed grouped in an independent, define cluster that is closely related, albeit distinguishable, from that of Margarita-related viruses that previously circulated in the western part of Cuba. In addition, the 2001-2003 viruses showed a branched pattern with a level of sequence diversification similar to that observed in the eastern 1993-1997 viruses. Interestingly, a significant fraction (about 54%) of the mutations found in the E2 sequence led to amino acid replacements. This high rate of non-synonymous mutations was not found in the previous Cuban epizootic and has not been reported for other CSF outbreaks. In spite of these amino acid replacements, no antigenic changes were observed in the reactivity of different isolates with CSFV-specific MAbs and polyclonal sera. The phylogenetic tree derived from 409 nucleotides of NS5B gene of seven isolates and Margarita strain, was consistent with that obtained from E2 sequences. In this region, encoding a non-structural protein, a low level of fixation of non-synonymous mutations was observed. The results obtained suggests that epidemiological factors affecting CSFV spread during the current epizootic in Cuba can favour the fixation of non-synonymous mutation in the E2 gene, which could be associated with a lower severity in the clinical signs developed by most of the affected animals. (c) 2005 Published by Elsevier B.V.