Dicistroviridae


Dicistroviridae is a family of viruses in the order Picornavirales. Invertebrates, including aphids, leafhoppers, flies, bees, ants, and silkworms, serve as natural hosts. There are 16 species in this family, assigned to three genera. Diseases associated with this family include: DCV: increased reproductive potential. extremely pathogenic when injected with high associated mortality. CrPV: paralysis and death.

Taxonomy

Although many dicistroviruses were initially placed in the Picornaviridae, they have since been reclassified into their own family. The name is derived from the characteristic dicistronic arrangement of the genome.
This family is a member of the Order Picornavirales. Within this order, the gene order is the gene order of the nonstructural proteins Hel-Pro-RdRp. The Dicistroviridae can be distinguished from the members of the taxa by the location of their structural protein genes at the 3' end rather than the 5' end and by having two genomic segments rather than a single one.
The family contains the following genera and species:
Genus: Aparavirus
Genus: Cripavirus
Genus: Triatovirus
Linepithema humile virus 1 is possibly a member of Dicistroviridae, of unclear placement.

Structure

Viruses in Dicistroviridae are non-enveloped, with icosahedral geometries, and T=pseudo3 symmetry. The diameter is around 30 nm. Genomes are linear and non-segmented, around 8.5-10.2kb in length. The genome has 2 open reading frames.
GenusStructureSymmetryCapsidGenomic arrangementGenomic segmentation
AparavirusIcosahedralPseudo T=3Non-envelopedLinear
CripavirusIcosahedralPseudo T=3Non-envelopedLinearMonopartite

Life cycle

Entry into the host cell is achieved by penetration into the host cell. Replication follows the positive stranded RNA virus replication model. Positive stranded RNA virus transcription is the method of transcription. Translation takes place by viral initiation, and ribosomal skipping. Invertebrates serve as the natural host. Transmission routes are contamination.
GenusHost detailsTissue tropismEntry detailsRelease detailsReplication siteAssembly siteTransmission
AparavirusInvertebrates: honeybee, bumblebees-UnknownUnknownCytoplasmCytoplasmUnknown
CripavirusInvertebrates-Cell receptor endocytosisBuddingCytoplasmCytoplasmFood

RNA structural elements

Many of the Dicistroviridae genomes contains structured RNA elements. For example, the Cripaviruses have an internal ribosome entry site, which mimics a Met-tRNA and is used in the initiation of translation.