Notes on Genus: Idaeovirus

icosahedra

Type member: Raspberry bushy dwarf 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 Idaeovirus currently consists of one virus, raspberry bushy dwarf, and the name is derived from the scientific name for raspberry, Rubus idaeus. It was originally placed with the genus Ilarvirus in the family Bromoviridae because of its isometric particles, pollen-associated transmission and multi-partite genome. Now that sequence data is available, it is clear that the genome strategy is quite distinct, justifying a genus separate from that family.

Morphology

Virions isometric (icosahedral) but slightly flattened, not enveloped, of three types but similar in size (33 nm). The nucleocapsids appear to be angular.

Virions composed of 24 % nucleic acid and 76 % protein.

Genome

Three components (2 genomic and 1 subgenomic), linear, single stranded, positive sense RNA distributed among the particles which can therefore be separated on their densities. The three RNAs have c. 5400 (RNA1), 2200 (RNA2) and 1000 (subgenomic RNA3) nucleotides. The 3'-terminal regions of the RNAs may form a stem loop structure.

Genus Genomic Organization

RNA1 has a single open reading frame, RNA2 has two open reading frames and RNA3 is the encapsidated subgenomic of RNA2 expressing the coat protein

Type Member Genomic Organization

RNA1 has a single open reading frame:
1. 191.1 kDa Polymerase: multi-function replication protein containing methyl transferase, helicase and RNA polymerase domains

RNA2 has two open reading frames:
2. Movement protein, 38.9 kDa with some homology to the alfalfa mosaic virus 32 kDa protein (3a)
3. Coat protein, 30.5 kDa

RNA3 is an encapsidated subgenomic expressing the coat protein