Notes on Family: Tombusviridae
- Members of this Family
- General Description
- Genera in the Family
- All Known Sequences
- Curated Sequences
General DescriptionThis family is characterised by its icosahedral particles, a ssRNA genome with (usually) five open reading frames (some of which are expressed from subgenomic RNAs) and transmission through soil or water. The genera have different genome structures and there is little nucleotide similarity between viruses of different genera.
MorphologyVirions isometric and icosahedral (T=3), not enveloped, 28-34 nm in diameter. Nucleocapsids with obvious regular surface structure (of granular appearance). 32 capsomeres per nucleocapsid (virion composed of 180 protein subunits).
Particles contain 17 % nucleic acid.
GenomenMonopartite (except Dianthovirus), linear single stranded positive sense RNA. Total genome 4000-5400 nucleotides long. 3' terminus has no poly (A) tract. 5' terminus probably has a methylated nucleotide cap but this has been demonstrated only in some members.
Genera in the FamilyGenera are distinguished by genome organization and also by phylogenetic analysis of the replication and movement proteins.
|Genome (kb)||ORFs||CP (kDa)||CP at 3'-end?|
|Alphanecrovirus||28||3.6-3.7||5 or 6||27-30||sometimes||Fungus vector|
|Betanecrovirus||28||3.6-3.7||5 or 6||27-30||sometimes||Fungus vector|