VIRION
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Non-enveloped, head-tail structure. Head is about 60 nm in diameter. The tail is non-contractile, has 6 short subterminal fibers. The capsid is icosahedral with a T=7 symmetry.
GENOME
Linear, dsDNA genome of about 40-42 kb encoding for 55 genes.
GENE EXPRESSION
REPLICATION
CYTOPLASMIC
- The phage attaches to target cell adhesion receptors through its tail fibers.
- Ejection by short tail system: viral DNA is injected in host cell periplasm.
- Transcription of class I genes by host RNA polymerase before the viral genome completely exits out of capsid.
- Transcription of class II genes by T7 RNA polymerase.
- Bacterial genome degradation
- Replication of genomic DNA by T7 DNA polymerase, formation of viral genome concatemers.
- Transcription of class III genes by T7 RNA polymerase.
- Assembly of empty procapsids and viral genome packaging.
- Mature virions are released from the cell by lysis.