U.S. Geological Survey, Western Fisheries Research Center, Seattle, WA 98115, USA.
Virus Res. 2011 Jun;158(1-2):116-23. doi: 10.1016/j.virusres.2011.03.019. Epub 2011 Mar 31.
Beginning in 1988, the Chinook salmon embryo (CHSE-214) cell line was used to isolate a novel virus from spawning adult trout in the state of California, USA. Termed the cutthroat trout (Oncorhynchus clarkii) virus (CTV), the small, round virus was not associated with disease, but was subsequently found to be present in an increasing number of trout populations in the western USA, likely by a combination of improved surveillance activities and the shipment of infected eggs to new locations. Here, we report that the full length genome of the 1988 Heenan Lake isolate of CTV consisted of 7269 nucleotides of positive-sense, single-stranded RNA beginning with a 5' untranslated region (UTR), followed by three open reading frames (ORFs), a 3' UTR and ending in a polyA tail. The genome of CTV was similar in size and organization to that of Hepatitis E virus (HEV) with which it shared the highest nucleotide and amino acid sequence identities. Similar to the genomes of human, rodent or avian hepeviruses, ORF 1 encoded a large, non-structural polyprotein that included conserved methyltransferase, protease, helicase and polymerase domains, while ORF 2 encoded the structural capsid protein and ORF 3 the phosphoprotein. Together, our data indicated that CTV was clearly a member of the family Hepeviridae, although the level of amino acid sequence identity with the ORFs of mammalian or avian hepeviruses (13-27%) may be sufficiently low to warrant the creation of a novel genus. We also performed a phylogenetic analysis using a 262nt region within ORF 1 for 63 isolates of CTV obtained from seven species of trout reared in various geographic locations in the western USA. While the sequences fell into two genetic clades, the overall nucleotide diversity was low (less than 8.4%) and many isolates differed by only 1-2 nucleotides, suggesting an epidemiological link. Finally, we showed that CTV was able to form persistently infected cultures of the CHSE-214 cell line that may have use in research on the biology or treatment of hepevirus infections of humans or other animals.
自 1988 年以来，奇努克鲑鱼胚胎（CHSE-214）细胞系被用于从美国加利福尼亚州产卵的成年鳟鱼中分离出一种新型病毒。这种病毒被称为虹鳟鱼病毒（CTV），是一种小型圆形病毒，与疾病无关，但随后在西美的越来越多的鳟鱼种群中发现了这种病毒，这可能是由于监测活动的改善和感染卵被运送到新地点的综合作用。在这里，我们报告称，1988 年海嫩湖分离株的 CTV 全长基因组由 7269 个核苷酸组成，为带有 5'非翻译区（UTR）的正链单链 RNA，随后是三个开放阅读框（ORF）、3'UTR 和 polyA 尾。CTV 的基因组大小和组织与戊型肝炎病毒（HEV）相似，与 HEV 共享最高的核苷酸和氨基酸序列同一性。与人类、啮齿动物或禽类 hepeviruses 的基因组相似，ORF 1 编码一个大型非结构多蛋白，其中包括保守的甲基转移酶、蛋白酶、解旋酶和聚合酶结构域，而 ORF 2 编码结构衣壳蛋白，ORF 3 编码磷蛋白。总之，我们的数据表明，CTV 显然是 hepeviridae 家族的一员，尽管与哺乳动物或禽类 hepeviruses 的 ORF 氨基酸序列同一性（13-27%）可能足够低，需要创建一个新属。我们还使用 ORF 1 内的 262nt 区域对从美国西部七个不同地理地点饲养的七种鳟鱼中获得的 63 个 CTV 分离株进行了系统发育分析。尽管这些序列分为两个遗传枝，但总的核苷酸多样性很低（小于 8.4%），许多分离株仅相差 1-2 个核苷酸，表明存在流行病学联系。最后，我们表明 CTV 能够形成持续感染 CHSE-214 细胞系的培养物，这可能有助于研究人类或其他动物的 hepevirus 感染的生物学或治疗方法。
