Notes on Genus: Hepatovirus
Type member: Hepatitis A virus
The genus Hepatovirus
(from the greek hepatos
= liver) is one of the genera in the family Picornaviridae
. Genome organisation is fairly conserved within the family but members of this genus have a 5'-UTR which has no polyC tract, there is no leader protein, the internal capsid (1A) protein is extremely small and the 2A protein is not a protease.
Virions isometric (icosahedral), not enveloped 30 nm in diameter, made of 60 units (protomers) each consisting of one molecule of each of three surface coat proteins.
Monopartite positive sense single-stranded RNA 7.0-7.5 kb in length. There is a genome-linked protein (VPg) at the 5'-terminus and a 3'-polyA tail.
Genus Genomic Organization
The RNA encodes a single polyprotein that is subsequently processed into the functional products. The major structural proteins are encoded near the N-terminus.
Type Member Genomic Organization
The genome of about 7,500 nucleotides is translated into a single polyprotein, which is subsequently processed into eleven products:
|1A ||2.5 kDa||Coat protein VP4 (internal capsid protein)|
|1B ||24.8 kDa||Coat protein VP2 (surface capsid protein)|
|1C ||27.8 kDa||Coat protein VP3 (surface capsid protein)|
|1D ||33.2 kDa||Coat protein VP1 (surface capsid protein)|
|2A ||22.0 kDa||non-structural protein|
|2B ||12.1 kDa||non-structural protein|
|2C ||38.5 kDa||non-structural protein|
|3A ||8.0 kDa||non-structural protein|
|3B ||2.5 kDa||Genome-linked protein (VPg)|
|3C ||24.1 kDa||protease|
|3D ||56.3 kDa||polymerase|