Notes on Genus: Erbovirus


Type member: Equine rhinitis B virus


General Description

The genus Erbovirus (from the type member Equine rhinitis B 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 kDaLeader protease
1A  7.3 kDaCoat protein VP4 (internal capsid protein)
1B  28.5 kDaCoat protein VP2 (surface capsid protein)
1C 25.2 kDaCoat protein VP3 (surface capsid protein)
1D 35.3 kDaCoat protein VP1 (surface capsid protein)
2A 1.7 kDanon-structural protein
2B 33.3 kDanon-structural protein
2C 35.1 kDanon-structural protein
3A 15.8 kDanon-structural protein
3B 2.5 kDaGenome-linked protein (VPg)
3C 26.9 kDaprotease
3D 53.0 kDapolymerase