Notes on Genus: Cardiovirus
icosahedra
Type member: Encephalomyocarditis virus
Contents
General Description
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.
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.
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 |
