Secoviridae


Secoviridae is a family of viruses in the order Picornavirales. Plants serve as natural hosts. There are currently 86 species in this family, divided among 8 genera or not assigned to a genus. The family was created in 2009 with the grouping of families Sequiviridae, now dissolved, and Comoviridae, now subfamily Comovirinae, along with the then unassigned genera Cheravirus, Sadwavirus, and Torradovirus.

Structure

Viruses in Secoviridae are non-enveloped, with icosahedral geometries, and T=pseudo3 symmetry. The diameter is around 25-30 nm. Genomes are linear and segmented, bipartite, around 24-7kb in length.
GenusStructureSymmetryCapsidGenomic arrangementGenomic segmentation
SequivirusIcosahedralPseudo T=3Non-envelopedLinearMonopartite
SadwavirusIcosahedralPseudo T=3Non-envelopedLinearSegmented
NepovirusIcosahedralPseudo T=3Non-envelopedLinearSegmented
FabavirusIcosahedralPseudo T=3Non-envelopedLinearSegmented
ComovirusIcosahedralPseudo T=3Non-envelopedLinearSegmented
CheravirusIcosahedralPseudo T=3Non-envelopedLinearSegmented
TorradovirusIcosahedralPseudo T=3Non-envelopedLinearSegmented
WaikavirusIcosahedralPseudo T=3Non-envelopedLinearMonopartite

Life cycle

Viral replication is cytoplasmic. 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. The virus exits the host cell by tubule-guided viral movement.
Plants serve as the natural host. Transmission routes are mechanical.
GenusHost detailsTissue tropismEntry detailsRelease detailsReplication siteAssembly siteTransmission
SequivirusPlants-Viral movement; mechanical inoculationViral movementCytoplasmCytoplasmMechanical inoculation: aphids; Mechanical inoculation: Cavariella aegopodii; Mechanical inoculation: Cavariella pastinacae
SadwavirusPlants-Viral movement; mechanical inoculationViral movementCytoplasmCytoplasmNematodes; mites; thrips
NepovirusPlants-Viral movement; mechanical inoculationViral movementCytoplasmCytoplasmNematodes; mites; thrips
FabavirusPlants-Viral movement; mechanical inoculationViral movementCytoplasmCytoplasmMechanical inoculation: aphids
ComovirusPlants-Viral movement; mechanical inoculationViral movementCytoplasmCytoplasmMechanical inoculation: beetles
CheravirusPlants-Viral movement; mechanical inoculationViral movementCytoplasmCytoplasmNematodes; mites; thrips
TorradovirusPlants-Viral movement; mechanical inoculationViral movementCytoplasmCytoplasmUnknown
WaikavirusGramineaePhloem; phloem parenchyma; bundle sheathViral movementViral movementCytoplasmCytoplasmMechanical innocuation: aphids; mechanical innocuation: leafhoppers

Taxonomy

Group: ssRNA

Evolution

The subfamily Comovirinae evolved ~1,000 years ago with extant species diversifying between 50 and 250 years ago. This time period coincides with the intensification of agricultural practices in industrial societies.
The mutation rate has been estimated to be 9.29×10−3 to 2.74×10−3 subs/site/year.