A prophage is a bacteriophage (often shortened to "phage") genome
inserted and integrated into the circular bacterial DNA chromosome or
existing as an extrachromosomal plasmid. This is a latent form of a
phage, in which the viral genes are present in the bacterium without
causing disruption of the bacterial cell. Pro means ''before'', so,
prophage means the stage of a virus in the form of genome inserted
into host DNA before attaining its real form inside host.
2 Zygotic induction
4 See also
Upon detection of host cell damage, such as UV light or certain
chemicals, the prophage is excised from the bacterial chromosome in a
process called prophage induction. After induction, viral replication
begins via the lytic cycle. In the lytic cycle, the virus commandeers
the cell's reproductive machinery. The cell may fill with new viruses
until it lyses or bursts, or it may release the new viruses one at a
time in a reverse endocytotic process. The period from infection to
lysis is termed the latent period. A virus following a lytic cycle is
called a virulent virus. Prophages are important agents of horizontal
gene transfer, and are considered part of the mobilome. All families
of bacterial viruses with circular (single-stranded or
double-stranded) DNA genomes or replicating their genomes through a
circular intermediate (e.g., Caudovirales) have temperate members.
Main article: Zygotic induction
If a target cell doesn't have the same prophage, upon infection by a
phage the lytic pathway is immediately activated. This phenomenon is
called zygotic induction.
^ Krupovic M, Prangishvili D, Hendrix RW, Bamford DH (2011). "Genomics
of bacterial and archaeal viruses: dynamics within the prokaryotic
virosphere". Microbiol Mol Biol Rev. 75 (4): 610–635.
doi:10.1128/MMBR.00011-11. PMC 3232739 .
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