Notes on Genus: Parechovirus
Type member: Human parechovirus
The genus Parechovirus
(from the former name of the type member, e
rphan) 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 without a polyC tract, and there is neither a leader protease nor an internal capsid (1A) protein.
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 c.
7.3 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 at the N-terminus.
Type Member Genomic Organization
The genome of about 7,300 nucleotides is translated into a single polyprotein, which is subsequently processed into ten products:
|1B ||31.7 kDa||Coat protein VP2 (surface capsid protein)|
|1C ||28.3 kDa||Coat protein VP3 (surface capsid protein)|
|1D ||26.4 kDa||Coat protein VP1 (surface capsid protein)|
|2A ||16.6 kDa||non-structural protein, possibly a protease|
|2B ||13.5 kDa||non-structural protein|
|2C ||37.9 kDa||non-structural protein|
|3A ||13.3 kDa||non-structural protein|
|3B ||2.2 kDa||Genome-linked protein (VPg)|
|3C ||22.5 kDa||protease|
|3D ||53.7 kDa||polymerase|