Non-enveloped, head-tail structure. The capsid is about 55 nm in diameter, probably with a T=4 icosahedral symmetry . The tail is non-contractile, about 27 nm in length, and has a collar with 12 appendages attached to the neck region that are important for host cell recognition and entry.


Linear, dsDNA genome of about 16 to 20 kb encoding between 20 and 30 genes, with a terminal protein covalently attached at either DNA end.




  1. Adsorption: the phage attaches to target cell through its tail fibers.
  2. Ejection by short tail system: viral DNA is injected in host cell periplasm.
  3. Transcription and translation of early genes
  4. Replication of genomic DNA by the viral DNA polymerase, formation of viral genome concatemers.
  5. Transcription and translation of late genes
  6. Assembly of empty procapsids and viral genome packaging.
  7. Mature virions are released from the cell by lysis.