Bacteriophage

A virus whose host is a bacterial cell; A virus that exclusively infects bacteria. It generally has a protein coat surrounding the genome (DNA or RNA). One of the coliphages most extensively studied is the lambda phage, which is also one of the most important.

Discovered in 1917 by Felix d’Herelle (fr. “bacteria eaters”), a bacteriophage is a virus that attaches to, injects its DNA into, and multiplies inside bacteria; which causes bacteria to die. Often abbreviated as simply phage. Another name for virus. As an example, bacteriophage lambda is commonly used as a vector in rDNA experiments in Escherichia coli and attaches to a specific receptor, which in the bacteria also normally functions in sugar transport across the cell wall. Viruses come in many shapes and sizes.

A virus that destroys bacteria.

Correct term for the more commonly used one—‘phages’—under which heading details are given.

A virus, sometimes called a bacterial virus but more generally simply phage, that causes bacteria to break down (lyse).

A virus that attacks bacteria. In general, a phage consists of a head, tail, and tail fibers, all composed of protein molecules, and a core of DNA. The tail and tail fibers are responsible for attachment to the bacterial surface and for injection of the DNA core into the host cell. The phage grows and replicates in the bacterial cell, which is eventually destroyed with the release of new phages. Each phage acts specifically against a particular species of bacterium. This is utilized in phage-typing, a technique of identifying bacteria by the action of known phages on them.

A VIRUS which invades a bacterium. Containing either single-stranded or double stranded DNA or RNA, a particular phage generally may infect one or a limited number of bacterial strains or species. After infection, once phage nucleic acid has entered the bacterium, a cycle may result whereby the bacteria are programmed to produce viral components, which are assembled into virus particles and released when the bacteria lyse (disintegrate). Other (temperate) phages induce a non-lytic, or lysogenic, state, in which phage nucleic acid integrates stably into, and replicates with, the bacterial chromosome. This relationship can revert to a lytic cycle and production of new phages. In the process the phage may carry small amounts of donor bacterial DNA to a ‘new host: the production of diphtheria toxin by Corynebacterium diphtheriae and of erythrogenic toxin by Streptococcus pyogenes are well-known examples of this effect. Phages have been used in experimental treatment of certain rare metabolic disorders in the hope that they will carry into body cells the enzyme or other chemical which is missing in the patient.

A virus that infects and lyses bacteria. It consists of a head that contains either DNA or RNA and a tail by which it attaches to the host cell.