Temperate phages are bacteriophages that can choose between the lytic and the lysogenic pathways of development. The lytic pathway is similar to that of virulent phages. In the lysogenic pathway, the virus remains dormant until induction. Temperate bacteriophages start their life cycle when they adsorb to permissive host. After injecting their genome into the host cell, they produce a set of early proteins and a few copies of their genome. At this stage a decision "lysis versus lysogeny" is made. Usually, in poor growth conditions of the host cell the phage chooses lysogenic pathway, because the number of progeny it can produce in such cell is usually low. When lysogeny is chosen, the phage integrates its genetic material with the host cell. It may be done by physical incorporation of the phage genome into host genome, or the prophage may be integrated as a stably maintained plasmid.
When a prophage is induced, it starts to produce viral proteins and copies of the viral genome using bacterial resources and biosynthetic apparatus. Progeny virus particles are formed and, after completing the cycle, released during host cell lysis. The animation showing the life cycle of a temperate bacteriophage is shown below: