Notes on Genus: Cytorhabdovirus

enveloped bacilliform

Type member: Lettuce necrotic yellows virus

General Description

This is one of 2 plant virus genera in the family Rhabdoviridae. It was previously known as Plant Rhabdovirus group A. The genus is characterised by its bacilliform, enveloped, particles which contain a monopartite ssRNA genome and which mature in the cytoplasm of the host plant cell. The name derives from the Greek cyto = cell and rhabdos = rod.

Morphology

Virions regular in shape and size to pleomorphic in shape and size (in unfixed preparations), bacilliform (when fixed prior to negative staining), enveloped, 200-350 nm long and 70-95 nm in diameter. There are distinct surface projections (spikes) dispersed evenly over all the surface. Nucleocapsids filamentous (when uncoiled), with obvious regular cross-banding and with a distinct central canal. Symmetry helical with pitch of 4.2-4.7 nm.

Virions composed of 1 % nucleic acid, 70 % protein and 25 % lipid.

Genome

Monopartite, linear, single-stranded, negative sense RNA, 11000-15000 nucleotides long.

Genus Genomic Organization

The genome organisation is typical of the family with the "standard" genes N, P, M, G and L in order on the template strand. Depending on the species, there are one or more additional genes located between P and M.

Type Member Genomic Organization

There are 6 genes which are listed here in their order on the template strand (i.e. from 3' to 5' with respect to the virion strand):

ORF	Gene	Product	Function
1	N	50.7 kDa	Coat protein (nucleocapsid)
2	P	32.5 kDa	Phosphoprotein
3	4b	33.7 kDa	unknown function
4	M	19.5 kda	Matrix protein
5	G	62.3 kda	Glycoprotein
6	L	236.6 kDa	Polymerase