The development of temperate phages: Lysogeny
* The lysogenic cycle replicates the phage genome without destroying the host
* The viral DNA molecule is incorporated into the host cell’s chromosome
*This integrated viral DNA is known as a prophage
* Every time the host divides, it copies the phage DNA and passes the copies to daughter cells
* It is relatively harmless and continues to remain in the position until the lytic cycle is triggered.
* It may be spontaneous or due to certain external conditions such as radiation exposure.
* Then the prophage becomes active and a lytic cycle initiates resulting in the lysis of the cell wall.
* After penetration, the phage DNA gets integrated into bacterial DNA and gets replicated along with the bacterial genome.
* As the bacterial genome is inserted into the bacterial genome and bacteria continue to perform the normal activities, the viral genome gets transferred to the progenies as well.
* Bacterial cells containing a prophage are called lysogenic cells.
* The lysogenic cells (having a prophage) may exhibit new properties, e.g. Corynebacterium diphtheriae and Clostridium botulinum, when containing certain prophage DNAs, synthesize toxins, which are harmful.
* Examples of lysogenic phage include lambda (λ) phage.
* Due to the ability to insert their genome specifically and replicate, they are used in genetic recombination.
