Notes on Genus: Megabirnavirus


Type member: Rosellinia necatrix megabirnavirus 1


General Description

The genus is the only member of the family Megabirnaviridae and currently consists of only one virus. The virus infects fungi and its genome is much larger than that of other dsRNA viruses. It is named for its large (mega) bipartite dsRNA genome.


Virions are isometric (icosahedral) and about 50 nm in diameter.


Bipartite dsRNA with segments of about 9 and 7 kbp.

Genus Genomic Organization

There are two ORFs predicted on each RNA segment.

Type Member Genomic Organization

RNA1 encodes the single major capsid protein of 135 kDa and an RNA polymerase of 123 kDa that may be expressed with the capsid protein by ribosomal frameshift. The two ORFs on RNA2 (152 and 24 kDa) have no homologies with known proteins and their functions are therefore unknown.