Notes on Genus: Varicosavirus

rigid rods

Type member: Lettuce big-vein associated 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

Members of this genus have rather labile rod shaped particles and are transmitted internally in spores of the chytrid fungus Olpidium brassicae. The name arises from the apparently swollen (varicose) veins that were thought to be caused in lettuce by the type member. Unfortunately, recent data suggest that these symptoms are actually caused by Mirafiori lettuce big-vein virus, a member of the genus Ophiovirus, with which LBVaV is often associated.

Morphology

Virions rod-shaped, not enveloped, straight or slightly flexuous, with distinct central canal. They are 320-360 nm long and c. 18 nm wide, with a pitch of 5nm.

Genome

Although orginally believed to be dsRNA and possibly bipartite, it is now known to be bipartite single stranded negative sense RNA.

Genus Genomic Organization

Only the type member has been sequenced. RNA1 is about 6.8kb and encodes a single polymerase gene while the coat protein and other products of unknown function are encoded on RNA2 (6.1 kb).

Type Member Genomic Organization

RNA1 (6.8 kb) encodes a 232 kDa polymerase (L) gene in the negative sense.

RNA2 (6.1 kb) also codes in the negative sense. The genes identified are listed here in their order on the template strand (i.e. from 3' to 5' with respenct to the virion strand):

The coding strategy and the sequences of the polymerase and coat protein show similarity to rhabdoviruses.