Notes on Genus: Barnavirus


Type member: Mushroom bacilliform virus


General Description

The genus Barnavirus (bacilliform RNA virus) is the only genus in the family Barnaviridae. The single member is the only known ssRNA virus that infects fungi and it has distinctive bacillifom virions.


Virions are bacilliform, not enveloped, about 18-20 nm in diameter and 48-53 nm long. There are no obvious surface projections. The virions contain about 20 % nucleic acid.


Monopartite, linear, single stranded, positive sense RNA of about 4kb. The 3' terminus has no poly(A) tract and there appears to be no cap at the 5' terminus.

Genus Genomic Organization

A total of seven open reading frames have been identified but it is not clear whether all are expressed in vivo. The coat protein is towards the 3'-terminus and is probably expressed from a 3'-terminal subgenomic RNA.

Type Member Genomic Organization

Seven open reading frames have been identified:

1. 20 kDaunknown function
2. 73 kDaprobable replication protein
3. 47 kDaRNA-dependent RNA polymerase
4. 22 kDaCoat protein, probably translated from a subgenomic RNA
5. 8 kDaunknown function: may not be expressed
6.    6.5 kDaunknown function: may not be expressed
7. 6 kDaunknown function: may not be expressed