Notes on Genus: Babuvirus
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icosahedra
Type member: Banana bunchy top virus
Contents
- Members of this Genus
- General Description
- Morphology
- Electron Micrograph
- Genome
- Genus Genomic Organization
- Genome Map
- Type Member Genomic Organization
- All Known Sequences
- Curated Sequences
General Description
The genus Babuvirus (from the type member Banana bunchy top virus) is one of two genera in the family Nanoviridae, which consists of viruses with small (18-19 nm) isometric virions and a multipartite (6 to 8 or more segments) ssDNA genome, each segment of which is circular and about 1kb in size. It currently contains the single virus with six segments and two unidirectionally transcribed ORFs on DNA1. Viruses of dicotyledonous plants that probably have 8 (or more) monocistronic segments, have been retained in the genus Nanovirus.Morphology
Virions isometric (icosahedral), not enveloped 18-19 nm in diameter.Genome
Six closed circular single stranded DNA components, each about 1kb in size. Additional DNA segments associated with some isolates and encoding replication-associated proteins are now regarded as alphasatellites.Genus Genomic Organization
Most segments are monocistronic. There is a putative stem loop structure in the non-coding region of each segment which has a conserved 9-nucleotide sequence at its apex.Type Member Genomic Organization
The six DNA components and their encoded proteins are:| DNA segment | Size (nt) | putative product |
| DNA-R (1) | 1111 | replication initiator protein M-Rep (34 kDa) and nested protein of about 5 kDa |
| DNA-U3 (2) | 1060 | Unknown protein U3 of about 10 kDa |
| DNA-S (3) | 1075 | coat protein (20 kDa) |
| DNA-M (4) | 1043 | movement protein (14 kDa) |
| DNA-C (5) | 1018 | cell-cycle link (Clink) protein (19 kDa) |
| DNA-N (6) | 1089 | nuclear shuttle protein NSP (17 kDa) |