Notes on Family: Picornaviridae



General Description

This family consists of viruses that infect vertebrates and which have isometric virions (30 nm) and a monopartite ssRNA genome which encodes a single polyprotein (except in the genus Dicipivirus, where it is split into two sections). It is of interest to plant virolgoists because of its association with the plant virus family Secoviridae within the order Picornavirales. The family Potyviridae is also often considered to be part of the picornavirus "superfamily". The name reflects the small (pico) RNA genome.


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 6.7-8.9 kb in length with a genome-linked protein (VPg) at the 5'-terminus and a 3'-polyA tail. It encodes a single polyprotein (two polyproteins in the genus Dicipivirus) that it is subsequently processed into the functional products:
L Leader protein (absent in some genera; sometimes with protease activity)
1A Coat protein VP4 (internal capsid protein; absent in some genera)
1B Coat protein VP2 (surface capsid protein)
1C Coat protein VP3 (surface capsid protein)
1D Coat protein VP1 (surface capsid protein)
2A non-structural protein (sometimes with protease activity; very small in some genera)
2B non-structural protein
2C non-structural protein
3A non-structural protein
3B Genome-linked protein (VPg)
3C protease
3D polymerase

Genera in the Family

Aphthovirus>1kb; polyC tractProtease+very
Aquamavirus500nt; no polyC tract None ++(2)
Avihepatovirus620nt; no polyC tract None++(2)
Cardiovirus800nt; polyC tractNot a protease++
Cosavirus>1kb; no polyC tractNone + very small
Dicipivirus*>1kb; no polyC tract None ++
Enterovirus 740nt; no polyC tract None+ Protease
Erbovirus900nt; polyC tract Protease+very
Hepatovirus700nt; no polyC tract Nonevery
Kobuvirus700nt; no polyC tract Protease-+
Megrivirus460nt; no polyC tract None ++
Parechovirus700nt; no polyC tract None-+
Sapelovirus440nt; no polyC tractNot a protease+ Protease
Salivirus700nt; no polyC tract Protease?+Protease
Senecavirus700nt; no polyC tractNot a protease+very
Teschovirus330nt; polyC tract Protease+very
Tremovirus500nt; no polyC tract None-+

* separate structural and non-structural polyproteins