Notes on Genus: Erbovirus

icosahedra

Type member: Equine rhinitis B virus

Contents

Members of this Genus General Description Morphology Electron Micrograph Genome Genus Genomic Organization Genome Map Type Member Genomic Organization Curated Sequences

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.

Morphology

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.

Genome

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

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