Levivirus

Levivirus is a genus of viruses in the family Leviviridae. These viruses are bacteriophages, meaning they infect bacteria. Specifically, leviviruses infect Gram-negative bacteria, with their host range primarily including species within the genus *Escherichia* and related genera. They are single-stranded RNA viruses with a positive-sense genome. The virion is non-enveloped and roughly spherical in shape.

The genome of a levivirus is small, typically around 3.5 to 4 kilobases in length. It encodes for a limited number of proteins, including structural proteins that form the viral capsid and non-structural proteins involved in replication and assembly. The replication cycle of leviviruses involves the direct translation of the viral RNA by the host cell's ribosomes, followed by replication of the RNA genome. Assembly of new virions occurs within the cytoplasm of the infected bacterium, and release is typically achieved through lysis of the host cell.

Leviviruses are generally considered to be lytic phages, meaning they replicate within the host bacterium and cause its destruction. However, the precise interaction and outcome can vary depending on the specific levivirus and its host. Their study has contributed to our understanding of RNA virus replication and bacteriophage biology. Examples of leviviruses include MS2 bacteriophage, which is a well-studied model organism in molecular biology research.