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I3-like virus

Molecular biology

VIRION

Nonenveloped, head-tail structure. The head is about 85 nm in diameter. Tails are contractile which is very rare among phages of high G+C branch of Gram-positive bacteria.

GENOME

Linear, dsDNA genome of about 156 kb, containing about 225 genes.

GENE EXPRESSION

Genes are transcribed by operons.

REPLICATION

CYTOPLASMIC

1. Adsorption: the phage attach to target cell trhough its tail fibers.
2. Viral lysozyme degrades cell wall locally
3. Injection: viral DNA is injected in host cell periplasm by contraction of the tail
4. Transcription and traduction of early genes
5. Replication of genomic DNA
6. Transcription and traduction of late genes
7. Assembly of new virions in host cell cytoplasm
8. Mature virions are released from the cell by lysis