Bullavirinae

Bullavirinae is a subfamily of viruses in the family Microviridae. Enterobacteria serve as natural hosts. There are 14 species in this subfamily, organized into three genera.

Taxonomy
The following genera and species are recognized:
 * Genus: Alphatrevirus; species:
 * Escherichia virus alpha3
 * Escherichia virus ID21
 * Escherichia virus ID32
 * Escherichia virus ID62
 * Escherichia virus NC28
 * Escherichia virus NC29
 * Escherichia virus NC35
 * Escherichia virus phiK
 * Escherichia virus St1
 * Escherichia virus WA45
 * Genus: Gequatrovirus; species:
 * Escherichia virus G4
 * Escherichia virus ID52 
 * Escherichia virus Talmos
 * Genus: Sinsheimervirus; species:
 * Escherichia virus phiX174

Structure
Viruses in Bullavirinae are non-enveloped, with icosahedral and round geometries, and T=1 symmetry. The diameter is around 30 nm. Genomes are circular, around 6.1kb in length.

Life cycle
Viral replication is cytoplasmic. Entry into the host cell is achieved by pilus-mediated adsorption into the host cell. Replication follows the ssDNA rolling circle model. DNA-templated transcription is the method of transcription. The virus exits the host cell by bacteria lysis.

Enterobacteria serve as the natural host. Transmission routes are passive diffusion.