Notes on Genus: Erbovirus
Type member: Equine rhinitis B virus
The genus Erbovirus
(from the type member E
virus) 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 of c.
900nt, which contains a polyC tract, and a leader protease. The 2A protein is extremely small.
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 and with a fourth internal capsid protein.
Monopartite positive sense single-stranded RNA c.
8.8 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 8,800 nucleotides is translated into a single polyprotein, which is subsequently processed into twelve products:
|L ||24.8 kDa||Leader protease|
|1A ||7.3 kDa||Coat protein VP4 (internal capsid protein)|
|1B ||28.5 kDa||Coat protein VP2 (surface capsid protein)|
|1C ||25.2 kDa||Coat protein VP3 (surface capsid protein)|
|1D ||35.3 kDa||Coat protein VP1 (surface capsid protein)|
|2A ||1.7 kDa||non-structural protein|
|2B ||33.3 kDa||non-structural protein|
|2C ||35.1 kDa||non-structural protein|
|3A ||15.8 kDa||non-structural protein|
|3B ||2.5 kDa||Genome-linked protein (VPg)|
|3C ||26.9 kDa||protease|
|3D ||53.0 kDa||polymerase|