bacteriophage (rus. бактериофаг otherwise фаг; вирус бактерий) — (from “bacteria” and Greek φᾰγω meaning "to devour") a virus able to infect bacterial cells.


Viruses that cause death (lysis) of infected bacteria are known as lytic bacteriophages (phages). The so-called moderate bacteriophages insert their own DNA into the bacterial chromosome. Synthesis of virus-specific proteins and nucleic acids in such phages is suppressed by a specific repressor, therefore the bacteria does not die and becomes "immune" to re-infection (lysogenic). The integration of the phage DNA into the bacterial genome may alter the antigenic and morphological properties of the bacterial cell, and synthesis of virulence factors (lysogenic conversion). With a moderate phage DNA replication occurs synchronously with the reproduction of lysogenic bacteria, but sometimes (in one for every 102-105 bacteria) the phage starts to proliferate spontaneously and lyses the cell. While replicating in the cell, some moderate bacteriophages are able to capture the bacterial genes and transfer them to a new host upon infection of another bacterial cell (transduction). The transducing phages transfer bacterial DNA only (generalised transduction) or viral DNA with regions of bacterial DNA (specialised transduction). Such phages are not able to produce progeny phage particles, i.e. they are defective. Such defective phages are used in genetic engineering as vectors. Acteriophage research has been useful in resolving a number of important problems in molecular biology and molecular genetics. The bacteriophage model was used to demonstrate that DNA is the physical carrier of heredity; to discover modification-restriction and transcription phenomena; to conduct research into replication, recombination, and morphogenesis. The bacteriophage classification system is based on antigenic structure, phage morphology, spectrum of action, chemical composition, etc. Most phages are DNA-containing viruses with a nucleocapsid organised according to mixed symmetry. According to the action spectrum the phages are classified into the following categories: typical phages (T-phages) lysing bacteria of separate types belonging to one species; monovalent phages lysing the bacteria of one species; and polyvalent phages lysing bacteria of several species.

Bacteriophage phi29 has a complex system of DNA packaging into capsid. This well-studied nanomotor can be chemically or genetically modified to be integrated into the liposomal membrane and to be used in drug delivery systems for controlled drug release at the pathological sites. Sensitive Sensors for in vitro diagnostics are being developed based on arrays of modified nanomotors that recognize different biomarkers.

Bacteriophages (their capsids), as well as other viruses, can be used as scaffolds, giving specific spatial arrangement to non-biogenic nanoparticles. Such "scaffolding" can not only create planar structures with a specific shape and size, but also enables one to design and create three-dimensional nanostructures, even rather complex ones such as a tetrahedron or a sphere, enabling the creation of nanostructures or materials with new useful properties for applications in various fields of nanotechnology.


T4 bacteriophage structure:  1 — head; 2 — tail; 3 — nucleic acid; 4 — capsid; 5 —
T4 bacteriophage structure: 1 — head; 2 — tail; 3 — nucleic acid; 4 — capsid; 5 — "collar"; 6 — tail's protein jacket; 7 — tail fibril; 8 — spikes; 9 — basal plate.


  • Kurochkin Ilya N.
  • Naroditsky Boris S.
  • Borisenko Grigory G.
  • Nesterenko Lyudmila N.


  1. Zhdanov V.M. Evolution of viruses (monograph) (in Russian) . — Moscow: Medicina, 1990. — 376 pp.
  2. Bacteriophage //Wikipedia, the free encyclopedia. — (reference date: 12.12.2011).
  3. NIH Nanomedicine Development Center // Peixuan Guo, 2006. —

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