Hepatitis E virus (HEV): Molecular cloning and sequencing of the full-length viral genome

Abstract

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. o tsst Academic PWSS, IIX.

Isolation and identification of hepatitis E virus in Xinjiang, China

“…All these biophysical characteristics suggest that HEV is similar to caliciviruses, as other investigators have suggested (Arankalle et al, 1988;Bradley et al, 1988). Reyes et al (1990) have recently reported that HEV might be a new virus of the Caliciviridae family, and Tam et al (1991) suggested that HEV represents either the prototype member of an as yet unclassified novel virus family or perhaps a separate genus within the Caliciviridae. Success in cultivating HEV in a human cell line in our laboratory will facilitate further research on HEV.…”

Genetic heterogeneity of hepatitis E virus in Darfur, Sudan, and neighboring Chad

“…IgG and IgM anti-HEV was detected with commercial assays (HEV Elisa and HEV IgM Elisa, Genelabs Diagnostics, Singapore Science Park). RT PCR was performed using the GeneAmp 9600 Thermocycler with primers targeting HEV ORF2 nucleotides 6,653-7,100 as described previously [Tam et al, 1991;Grandadam et al, 2004].…”

The Leu477 and Leu613 of ORF2-Encoded Protein Are Critical in Forming Neutralization Antigenic Epitope of Hepatitis E Virus Genotype 4

“…It occurs in both epidemic and sporadic forms in most developing countries of Asia (1,2), Africa (3) and Latin America (4). The mortality of acute HEV infection ranges from 0.5-1% among the general population to as high as up to 20% in pregnant women (5).…”