Picovirinae

VIRION

Non-enveloped, head-tail structure. Head is about 54 nm in diameter. The tail is non-contractile and has a collar with 12 appendages. The capsid is icosahedral with a T=3 symmetry.

GENOME

Linear, dsDNA genome of about 16 to 20 kb encoding between 20 and 30 genes.

GENE EXPRESSION

REPLICATION

CYTOPLASMIC

  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.