Secoviridae

Secoviridae
	Structure of the Cowpea mosaic virus based on PDB 2BFU
Virus classification
(unranked):	Virus
Realm:	Riboviria
Kingdom:	Orthornavirae
Phylum:	Pisuviricota
Class:	Pisoniviricetes
Order:	Picornavirales
Family:	Secoviridae
Genera
	See text

Secoviridae is a family of viruses in the order Picornavirales. Plants serve as natural hosts. There are 8 genera and 86 species in this family, one of which is unassigned to a genus.^[1]^[2]^[3]^[4] 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.^[4]

Taxonomy

The family includes the following genera (-virinae denotes subfamily and -virus denotes genus):^[4]

Comovirinae
- Comovirus
- Nepovirus
- Fabavirus
Unassigned to a subfamily:
- Cheravirus
- Sadwavirus
- Sequivirus
- Stralarivirus
  - Strawberry latent ringspot virus
- Torradovirus
- Waikavirus

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.^[1]^[2]^[3]

Genus	Structure	Symmetry	Capsid	Genomic arrangement	Genomic segmentation
Sequivirus	Icosahedral	Pseudo T=3	Non-enveloped	Linear	Monopartite
Sadwavirus	Icosahedral	Pseudo T=3	Non-enveloped	Linear	Segmented
Nepovirus	Icosahedral	Pseudo T=3	Non-enveloped	Linear	Segmented
Fabavirus	Icosahedral	Pseudo T=3	Non-enveloped	Linear	Segmented
Comovirus	Icosahedral	Pseudo T=3	Non-enveloped	Linear	Segmented
Cheravirus	Icosahedral	Pseudo T=3	Non-enveloped	Linear	Segmented
Torradovirus	Icosahedral	Pseudo T=3	Non-enveloped	Linear	Segmented
Waikavirus	Icosahedral	Pseudo T=3	Non-enveloped	Linear	Monopartite

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.^[1]^[2]^[3]

Genus	Host details	Tissue tropism	Entry details	Release details	Replication site	Assembly site	Transmission
Sequivirus	Plants	None	Viral movement; mechanical inoculation	Viral movement	Cytoplasm	Cytoplasm	Mechanical inoculation: aphids; Mechanical inoculation: Cavariella aegopodii; Mechanical inoculation: Cavariella pastinacae
Sadwavirus	Plants	None	Viral movement; mechanical inoculation	Viral movement	Cytoplasm	Cytoplasm	Nematodes; mites; thrips
Nepovirus	Plants	None	Viral movement; mechanical inoculation	Viral movement	Cytoplasm	Cytoplasm	Nematodes; mites; thrips
Fabavirus	Plants	None	Viral movement; mechanical inoculation	Viral movement	Cytoplasm	Cytoplasm	Mechanical inoculation: aphids
Comovirus	Plants	None	Viral movement; mechanical inoculation	Viral movement	Cytoplasm	Cytoplasm	Mechanical inoculation: beetles
Cheravirus	Plants	None	Viral movement; mechanical inoculation	Viral movement	Cytoplasm	Cytoplasm	Nematodes; mites; thrips
Torradovirus	Plants	None	Viral movement; mechanical inoculation	Viral movement	Cytoplasm	Cytoplasm	Unknown
Waikavirus	Gramineae	Phloem; phloem parenchyma; bundle sheath	Viral movement	Viral movement	Cytoplasm	Cytoplasm	Mechanical innocuation: aphids; mechanical innocuation: leafhoppers

Evolution

The subfamily Comovirinae evolved ~1,000 years ago with extant species diversifying between 50 and 250 years ago.^[5] This time period coincides with the intensification of agricultural practices in industrial societies.^{[citation needed]}

The mutation rate has been estimated to be 9.29×10⁻³ to 2.74×10⁻³ subs/site/year.^{[citation needed]}

References

^ ^a ^b ^c Thompson, JR; Dasgupta, I; Fuchs, M; Iwanami, T; Karasev, AV; Petrzik, K; Sanfaçon, H; Tzanetakis, I; van der Vlugt, R; Wetzel, T; Yoshikawa, N; ICTV Report Consortium (April 2017). "ICTV Virus Taxonomy Profile: Secoviridae". The Journal of General Virology. 98 (4): 529–531. doi:10.1099/jgv.0.000779. PMC 5657025. PMID 28452295.
^ ^a ^b ^c "Secoviridae". ICTV Online (10th) Report.
^ ^a ^b ^c "Viral Zone". ExPASy. Retrieved 15 June 2015.
^ ^a ^b ^c "Virus Taxonomy: 2020 Release". International Committee on Taxonomy of Viruses (ICTV). March 2021. Retrieved 20 May 2021.
^ Thompson, JR; Kamath, N; Perry, KL (2014). "An evolutionary analysis of the secoviridae family of viruses". PLOS ONE. 9 (9): e106305. Bibcode:2014PLoSO...9j6305T. doi:10.1371/journal.pone.0106305. PMC 4152289. PMID 25180860.