Prophage

Prophage is a term in microbiology that refers to the genetic material of a bacteriophage that is incorporated into the DNA of a bacterium and replicates with it. This process is a part of the lysogenic cycle, a phase in the life cycle of certain viruses, including bacteriophages, during which they integrate their DNA into the host's genome.

Overview

A prophage is formed when a bacteriophage infects a bacterium. The bacteriophage injects its DNA into the bacterium, where it becomes incorporated into the bacterial DNA. This integrated viral DNA is then replicated along with the bacterial DNA when the bacterium divides, producing copies of the virus within each new bacterium.

Lysogenic Cycle

The lysogenic cycle is one of two cycles of viral reproduction, the other being the lytic cycle. The lysogenic cycle is characterized by integration of the bacteriophage nucleic acid into the host bacterium's genome or formations of a circular replicon in the bacterial cytoplasm. In this condition the virus remains in the host cell without causing its lysis. The virus genome is replicated along with the host cell genome.

Role in Bacterial Evolution

Prophages are important agents of horizontal gene transfer, which increases genetic diversity among bacteria. They can carry accessory genes, such as toxin genes, among bacteria. This can lead to increased virulence in certain bacteria, such as those that cause diphtheria and cholera.

See Also

• Bacteriophage
• Lysogenic cycle
• Lytic cycle
• Horizontal gene transfer
• Virulence

References

• 
  Diagram of a prophage lifecycle
• 
  Illustration of a prophage