Notes on Genus: Hepevirus
Type member: Hepatitis E virus
The genus is the only member of the family Hepeviridae
and currently consists of only one virus. It shares some similarity in genome organisation with members of the family Caliciviridae
but there is no VPg at the 5'-terminus of the genome and the non-structural proteins are alpha-like and thus resemble those of members of the family Togaviridae
Virions isometric (icosahedral), not enveloped 27-34 nm in diameter.
Monopartite positive sense single-stranded c.
RNA 7.2 kb in length without a genome-linked protein (VPg) at the 5'-end but with a 3'-polyA tail.
Genus Genomic Organization
The RNA encodes 3 open reading frames. The largest ORF, towards the 5'-end of the genome is a polyprotein encoding the non-structural proteins. ORF2 encodes the coat protein and there is a third, smaller, ORF overlapping the other two encoding a protein of unknown function.
Type Member Genomic Organization
The genome of about 7,200 nucleotides has three open reading frames:
- Non-structural polyprotein (185 kDa) with motifs for methyltransferase, protease, helicase and RNA polymerase activity
- Coat protein (71 kDa)
- ORF3 (13 kDa) of unknown function