Notes on Genus: Megrivirus
Type member: Melegrivirus A
The genus Megrivirus
is one of the genera in the family Picornaviridae
and is named from the host of the type species (turkey, genus name Meleagris
). Genome organisation is fairly conserved within the family but members of this genus have no leader protease, a single 2A protein and one or more proteins of unknown function in the region immediately downstream of the capsid proteins.
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 9.1 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 9,100 nucleotides is translated into a single polyprotein, which is subsequently processed into at least twelve products:
||Coat protein VP4+VP2 precursor|
||17.9 kDa||Coat protein VP3 (surface capsid protein)|
||26.3 kDa||Coat protein VP1 (surface capsid protein)|
||22.6 kDa||non-structural protein|
||20.3 kDa||non-structural protein|
||41.8 kDa||non-structural protein|
||17.1 kDa||non-structural protein|
||Genome-linked protein (VPg)|