Notes on Genus: Aparavirus
Type member: Acute bee paralysis virus
This is one of two genera of insect-infecting viruses in the family Dicistroviridae
. The genomes have two polyproteins encoded on a single RNA but in other respects they are similar to those of the plant- and vertebrate-infecting viruses that make up the picornavirus "superfamily", which includes the families Secoviridae
. There are also similarities to the family Caliciviridae
. It differs from the sister genus Cripavirus
in the sequence and structure of the internal ribosome entry site (IRES) at the intergenic region (IGR) and members of the two genera are phylogenetically distinct.
Virions isometric (icosahedral), not enveloped, about 30 nm in diameter.
Monopartite positive sense single-stranded RNA 8.0-10.2 kb in length with a genome-linked protein (VPg) at the 5'-terminus and a 3'-polyA tail.
Genus Genomic Organization
The RNA encodes two polyproteins, the first of which has the domains of the non-structural proteins (helicase, protease and replicase) while the second consists of the (three or more) coat proteins. There is an internal ribosome entry site (IRES) at the intergenic region (IGR) between the two ORFs.
Type Member Genomic Organization
The genome of about 9,500 nucleotides is predicted to be translated into:
- Non-structural polyprotein (219.4 kDa) with (from N- to C- termini) helicase protease and polymerase domains
- Structural polyprotein (102.0 kDa) that is processed into at least three coat proteins