Notes on Genus: Levivirus


Type member: Enterobacteria phage MS2


General Description

This is one of the genera in the family Leviviridae. Members have a genome of less than 4 kb which encodes a separate lysis gene.


Virions isometric (icosahedral), not enveloped, c. 26 nm in diameter.


Monopartite, linear, postive sense ssRNA of 3.5-3.6 kb.

Genus Genomic Organization

There are 4 ORFs including a single capsid protein, a replicase and a lysis protein.

Type Member Genomic Organization

The 4 ORFs are
  • A protein, 43.9 kDa (required for attachment and virion maturation)
  • Capsid protein, 13.8 kDa
  • Lysis protein, 8.9 kDa
  • Replicase, 60.8 kDa