Notes on Genus: Cardiovirus
Type member: Encephalomyocarditis virus
The genus Cardiovirus
(from the greek kardia
= heart) 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 which contains a polyC tract and a small leader protein which is not a protease.
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 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.
Type Member Genomic Organization
The genome of about 7,800 nucleotides is translated into a single polyprotein, which is subsequently processed into twelve products:
|L ||7.9 kDa||Leader protein (not a protease)|
|1A ||7.4 kDa||Coat protein VP4 (internal capsid protein)|
|1B ||28.6 kDa||Coat protein VP2 (surface capsid protein)|
|1C ||25.2 kDa||Coat protein VP3 (surface capsid protein)|
|1D ||30.5 kDa||Coat protein VP1 (surface capsid protein)|
|2A ||16.9 kDa||non-structural protein|
|2B ||16.5 kDa||non-structural protein|
|2C ||36.6 kDa||non-structural protein|
|3A ||9.9 kDa||non-structural protein|
|3B ||2.3 kDa||Genome-linked protein (VPg)|
|3C ||21.8 kDa||protease|
|3D ||52.0 kDa||polymerase|