Notes on Genus: Partitivirus

icosahedra
icosahedra

Type member: Atkinsonella hypoxylon virus

Contents

General Description

This is now the only mycovirus genus in the family Partitiviridae. The name is from the Latin partitus, meaning "divided". Similar viruses of fungi with four genomic components are placed in the genus Chrysovirus (family Chrysoviridae). Some sequences with high similarity to partitiviruses have now been isolated from plants; it is not yet clear whether these are genuine plant pathogens, or whether they have been isolated from a parasitic fungus within the plant.

Morphology

Virions isometric (icosahedral), not enveloped, 30-35 nm in diameter.

Genome

Bipartite, linear, double stranded RNA. The segments are unrelated, separately encapsidated, and 1.4-2.2 kb in size. Additional segments of satellite or defective dsRNA may also be present.

Genus Genomic Organization

The segments are monocistronic and similar in size. RNA1 (the slightly larger segment) encodes an RNA-dependent RNA polymerase (77-86 kDa in currently sequenced members), while RNA2 encodes the coat protein (57-76 kDa in currently sequenced members).

Type Member Genomic Organization

  • RNA1 (2180 nt) encodes a polymerase of 77.6 kDa
  • RNA2 (2135 nt) encodes the coat protein of 73.7 kDa