Punavirus

VIRION

Non-enveloped, head-tail structure. The icosahedral head is about 85 nm in diameter and virions also produce head size variants (about 47-65 nm). The tail is long, 228 x 18 nm, contractile, has six 90 nm-long kinked fibers and a base plate.

GENOME

Linear, dsDNA genome of about 100 kb, encoding for approximately 100 proteins. The genome is terminally redundant and circularly permuted.

GENE EXPRESSION

Genes are transcribed by operons.

REPLICATION

CYTOPLASMIC

  1. Adsorption: the phage attaches to the target cell through its tail fibers. Two types of fibers are encoded by the phage to allow receptor tropism switching.
  2. Ejection of the viral DNA into host cell cytoplasm by contraction of the tail sheath.
  3. Transcription and translation of early genes.
  4. Synthesis of linear concatemers copies of viral DNA. Transcription and translation of late genes.
  5. Assembly of an empty procapsid and packaging of the genome.
  6. Viral tail fibers assembly and viral tail assembly.
  7. Mature virions are released from the cell by lysis.