prophage

bacteriology

Also known as: provirus

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Last updated

July 13, 2026

Quick Summary

A prophage is the dormant, noninfectious form of a bacteriophage (a virus that infects bacteria) within a host cell. When a bacteriophage infects a bacterium, its genetic material can integrate into the host's DNA, becoming a prophage. This integrated viral DNA replicates along with the bacterial chromosome during cell division, and the host bacterium typically remains healthy.12

However, under certain conditions, such as exposure to ultraviolet light, the prophage can be activated. It then excises itself from the bacterial chromosome, replicates, and produces new phage particles, ultimately leading to the destruction (lysis) of the host bacterium. This process, known as lysogeny, was extensively studied by André Lwoff. Lysogeny is a significant aspect of bacterial epidemiology, as it can impart new genetic functions to bacteria, sometimes leading to increased virulence.23

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episome
…become integrated is called a prophage. See lysogeny.
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…become integrated is called a prophage. See lysogeny.
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André Lwoff
…a noninfective form called a prophage. He demonstrated that under certain conditions this prophage gives rise to an infective form that causes lysis, or disintegration, of the bacterial cell; the viruses that are released upon the cell’s destruction are capable of infecting other bacterial hosts. Lwoff also discovered that vitamins…
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…a noninfective form called a prophage. He demonstrated that under certain conditions this prophage gives rise to an infective form that causes lysis, or disintegration, of the bacterial cell; the viruses that are released upon the cell’s destruction are capable of infecting other bacterial hosts. Lwoff also discovered that vitamins…
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virus
Lysogeny
…noninfective precursor phage, called the prophage, remain healthy and continue to grow until they are stimulated by some perturbing factor, such as ultraviolet light. The prophage DNA is then excised from the bacterial chromosome, and the phage replicates, producing many progeny phages and lysing the host bacterial cell. This process,…
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…noninfective precursor phage, called the prophage, remain healthy and continue to grow until they are stimulated by some perturbing factor, such as ultraviolet light. The prophage DNA is then excised from the bacterial chromosome, and the phage replicates, producing many progeny phages and lysing the host bacterial cell. This process,…
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