Notes on Genus: Tombusvirus


Type member: Tomato bushy stunt virus


General Description

The genus Tombusvirus (tomato bushy stunt virus group) is one of 11 genera in the family Tombusviridae. The genera are morphologically similar, with icosahedral particles and small, (usually) monopartite ss RNA genomes. Members of this genus have larger genomes (>4.6 kb) than other members of the family, 5 open reading frames and do not have the coat protein at the 3'-terminus of the RNA.


Virions isometric (icosahedral; T=3), not enveloped and about 30 nm in diameter. The nucleocapsids have an obvious regular, apparently round, surface structure. 32 capsomeres per nucleocapsid (virion composed of 180 protein subunits).

Virions composed of 17 % nucleic acid.


Monopartite, linear, single stranded, positive sense RNA of length c. 4800 nucleotides. The 3' terminus has no poly(A) tract. The 5' terminus probably has a methylated nucleotide cap.

Genus Genomic Organization

The RNA of all members investigated so far is translated into five putative products, including a polymerase, a 40-45 kDa coat protein translated from the larger of two subgenomic RNAs and two other products translated from the smaller subgenomic.

Type Member Genomic Organization

The RNA (of the cherry strain) is translated into five putative products:
1. 33 kDaPolymerase
2. 92 kDaPolymerase readthrough
3. 41 kDaCoat protein, translated from subgenomic RNA1 (2156nt)
4. 22 kDaMovement protein, translated from subgenomic RNA2 (935 nt)
5. 19 kDaunknown function, translated from subgenomic RNA2 (935 nt)