Phage identification of bacteria

As the name suggests, bacteriophage (literally bacteria eating from the Greek) were discovered by Edward Twort and Felix D’Herelle as lytic agents that destroyed bacterial cells (see [1] for a review of the history of their discovery and application). Bacteriophage are in fact viruses that specifically infect members of the bacterial kingdom. In the eukaryotic kingdom, the visible diversity of biological forms makes it unsurprising that viruses have a specific host range, since it is clear that the organisms affected by the different viruses are very different. However, in the bacterial kingdom, differences between bacterial genera are not as easy to detect, and differentiation between members of a species is often reliably determined only at the molecular level. Hence, in the field of bacteriology, the fact that viruses have evolved to specifically infect only certain members of a genus or species seems to be surprising. However, as the molecular recognition events involved in eukaryotic virus infection are elucidated, it is clear that even subtle difference in cell surface proteins has profound effects on binding and infection of eukaryotic viruses (see [3] for a review), and this is also true for the bacteria-virus interaction.