Notes on Genus: Aphthovirus

icosahedra

Type member: Foot-and-mouth disease 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 Aphthovirus (from the greek aphtha = vesicles in the mouth) is one of the genera in the family Picornaviridae. Genome organisation is fairly conserved within the family but members of this genus have a very long (>1kb) 5'-UTR which contains a polyC tract, a leader protease and a very short 2A protein. The type member is unusual in having three VPg proteins.

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 7.5-8.2 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, following the self-cleaving leader protease.

Type Member Genomic Organization

The genome of about 8,100 nucleotides is translated into a single polyprotein, which is subsequently processed into fourteen products:

L	22.8 kDa	Leader protein (protease)
1A	8.8 kDa	Coat protein VP4 (internal capsid protein)
1B	24.3 kDa	Coat protein VP2 (surface capsid protein)
1C	24.0 kDa	Coat protein VP3 (surface capsid protein)
1D	22.9 kDa	Coat protein VP1 (surface capsid protein)
2A	1.7 kDa	non-structural protein
2B	16.9 kDa	non-structural protein
2C	35.9 kDa	non-structural protein
3A	17.4 kDa	non-structural protein
3B	2.7 kDa	Genome-linked protein (VPg1)
3B	2.7 kDa	Genome-linked protein (VPg2)
3B	2.6 kDa	Genome-linked protein (VPg3)
3C	23.0 kDa	protease
3D	52.8 kDa	polymerase

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