Tam A W, Smith M M, Guerra M E, Huang C C, Bradley D W, Fry K E, Reyes G R
Molecular Virology Department, Genelabs Incorporated, Redwood City, California 94063.
Virology. 1991 Nov;185(1):120-31. doi: 10.1016/0042-6822(91)90760-9.
We have recently described the cloning of a portion of the hepatitis E virus (HEV) and confirmed its etiologic association with enterically transmitted (waterborne, epidemic) non-A, non-B hepatitis. The virus consists of a single-stranded, positive-sense RNA genome of approximately 7.5 kb, with a polyadenylated 3' end. We now report on the cloning and nucleotide sequencing of an overlapping, contiguous set of cDNA clones representing the entire genome of the HEV Burma strain [HEV(B)]. The largest open reading frame extends approximately 5 kb from the 5' end and contains the RNA-directed RNA polymerase and nucleoside triphosphate binding motifs. The second major open reading frame (ORF2) begins 37 bp downstream of the first and extends approximately 2 kb to the termination codon present 65 bp from the 3' terminal stretch of poly(A) residues. ORF2 contains a consensus signal peptide sequence at its amino terminus and a capsid-like region with a high content of basic amino acids similar to that seen with other virus capsid proteins. A third open reading frame partially overlaps the first and second and encompasses only 369 bp. In addition to the 7.5-kb full-length genomic transcript, two subgenomic polyadenylated messages of approximately 3.7 and 2.0 kb were detected in infected liver using a probe from the 3' third of the genome. The genomic organization of the virus is consistent with the 5' end encoding nonstructural and the 3' end encoding the viral structural gene(s). The expression strategy of the virus involves the use of three different open reading frames and at least three different transcripts. HEV was previously determined to be a nonenveloped particle with a diameter of 27-34 nm. These findings on the genetic organization and expression strategy of HEV suggest that it is the prototype human pathogen for a new class of RNA virus or perhaps a separate genus within the Caliciviridae family.
我们最近报道了戊型肝炎病毒（HEV）部分序列的克隆，并证实了其与经肠道传播（水源性、流行性）的非甲非乙型肝炎的病因学关联。该病毒由一个约7.5kb的单链正义RNA基因组组成，3'端有多聚腺苷酸化。我们现在报告代表HEV缅甸株[HEV(B)]全基因组的一组重叠、连续的cDNA克隆的克隆及核苷酸测序情况。最大的开放阅读框从5'端延伸约5kb，包含RNA指导的RNA聚合酶和核苷三磷酸结合基序。第二个主要开放阅读框（ORF2）在第一个开放阅读框下游37bp处开始，延伸约2kb至距多聚（A）残基3'末端延伸65bp处的终止密码子。ORF2在其氨基末端含有一个共有信号肽序列和一个衣壳样区域，该区域碱性氨基酸含量高，类似于其他病毒衣壳蛋白。第三个开放阅读框部分与第一个和第二个重叠，仅包含369bp。除了7.5kb的全长基因组转录本外，使用来自基因组3'端三分之一的探针在受感染肝脏中检测到两条约3.7kb和2.0kb的亚基因组多聚腺苷酸化信息。该病毒的基因组结构与5'端编码非结构蛋白、3'端编码病毒结构基因一致。该病毒的表达策略涉及使用三个不同的开放阅读框和至少三种不同的转录本。HEV先前被确定为直径27 - 34nm的无包膜颗粒。这些关于HEV基因组织和表达策略的发现表明，它是一类新型RNA病毒的人类病原体原型，或者可能是杯状病毒科内的一个独立属。
