Bacteriophage

A bacteriophage, or phage, is a virus that infects bacteria.

A bacteriophage, or phage, is a virus that infects bacteria. They are also called bacterial viruses and are among the most abundant biological entities on Earth. Bacteriophages are widely distributed and have been studied for their roles in bacterial ecology, genetics, and potential therapeutic use against antibiotic-resistant infections.

Definition and structure

Bacteriophages are viruses that infect bacteria, and some sources also note infection of archaea. They consist of nucleic acid (either DNA or RNA) packaged in a protein capsid, and many have distinctive head-and-tail structures.

Life cycle

Phages can follow a lytic cycle, in which new viral particles are produced and the host cell bursts, or a lysogenic cycle, in which viral genetic material is maintained within the host and may later become active.

Discovery and naming

Bacteriophages were described independently by Frederick W. Twort in 1915 and Félix d’Hérelle in 1917. D’Hérelle coined the term bacteriophage, meaning “bacteria eater.”

Scientific and medical importance

Phages have been important tools for studying genetics, nucleic acid replication, and protein synthesis. They are highly specific, often infecting only one or a few bacterial types. They are also being investigated as a potential treatment for bacterial infections, including drug-resistant infections.