Definition of Bacteriophage

A bacteriophage is a class of viruses that is responsible for infecting bacterial cells. They are also termed as phage and bacterial viruses and were first discovered by Twort and Herelle. The name bacteriophage was given by Herelle to such viral entities due to their bactericidal ability. There are thousands of bacteriophages and each phage is involved in infecting a few types of bacteria.

The structure of a bacteriophage is composed of a protein capsid that encloses the genetic material either DNA or RNA. The nucleic acid may be single or double-stranded. Bacteriophages have 3 basic structural forms i.e. icosahedron with tail, icosahedron that lacks a tail, and filamentous form.