Bacteriophages
A bacteriophage (informally, phage) is a virus that infects and replicates within bacteria. The term is derived from 'bacteria' and the Greek φαγεῖν phagein "to devour". Bacteriophages are composed of proteins that encapsulate a DNA or RNA genome, and may have relatively simple or elaborate structures. Their genomes may encode as few as four genes, and as many as hundreds of genes. Phage replicate within bacteria following the injection of their genome into the cytoplasm. Bacteriophage are among the most common and diverse entities in the biosphere.
Phages are widely distributed in locations populated by bacterial hosts, such as soil or the intestines of animals. One of the densest natural sources for phages and other viruses is sea water, where up to 9×108 virions per milliliter have been found in microbial mats at the surface, and up to 70% of marine bacteria may be infected by phages.They have been used for over 90 years as an alternative to antibiotics in the former Soviet Union and Eastern Europe, as well as in France.They are seen as a possible therapy against multi-drug-resistant strains of many bacteria.
Since ancient times, reports of river waters having the ability to cure infectious diseases have been documented, such as leprosy. In 1896, Ernest Hanbury Hankin reported that something in the waters of the Ganges and Yamuna rivers in India had marked antibacterial action against cholera and could pass through a very fine porcelain filter. In 1915, British bacteriologist Frederick Twort, superintendent of the Brown Institution of London, discovered a small agent that infected and killed bacteria. He believed the agent must be one of the following: a stage in the life cycle of the bacteria; an enzyme produced by the bacteria themselves; or a virus that grew on and destroyed the bacteria.
Twort's work was interrupted by the onset of World War I and shortage of funding. Independently, French-Canadian microbiologist Félix d'Hérelle, working at the
Phages are widely distributed in locations populated by bacterial hosts, such as soil or the intestines of animals. One of the densest natural sources for phages and other viruses is sea water, where up to 9×108 virions per milliliter have been found in microbial mats at the surface, and up to 70% of marine bacteria may be infected by phages.They have been used for over 90 years as an alternative to antibiotics in the former Soviet Union and Eastern Europe, as well as in France.They are seen as a possible therapy against multi-drug-resistant strains of many bacteria.
Since ancient times, reports of river waters having the ability to cure infectious diseases have been documented, such as leprosy. In 1896, Ernest Hanbury Hankin reported that something in the waters of the Ganges and Yamuna rivers in India had marked antibacterial action against cholera and could pass through a very fine porcelain filter. In 1915, British bacteriologist Frederick Twort, superintendent of the Brown Institution of London, discovered a small agent that infected and killed bacteria. He believed the agent must be one of the following: a stage in the life cycle of the bacteria; an enzyme produced by the bacteria themselves; or a virus that grew on and destroyed the bacteria.
Twort's work was interrupted by the onset of World War I and shortage of funding. Independently, French-Canadian microbiologist Félix d'Hérelle, working at the