The Third Age of Phage

PLoS Biology: The Third Age of Phage:
"So, naturalists observe, a flea Has smaller fleas that on him prey; And these have smaller still to bite 'em; And so proceed ad infinitum.—Jonathan Swift

If Jonathan Swift was wrong in envisioning his infinite series of parasites, the “ultimate flea” could be a DNA sequence whose sole biological property is to ensure its own reproduction. But close to the diminutive end of this parasitic spectrum, there are the phages-viruses that infect bacteria. Phages were discovered early in the 20th century, and, at first, interest focussed on the potential of phages as therapeutic tools in the fight against bacterial infectious diseases. The advent of antibiotics was an influential factor in sidelining this ambition. Then for many years the study of phages underpinned the development of modern molecular biology, but that too became pass. The third age of phage has begun only recently with the growing recognition that phages may be major players in the great planetary biogeochemical cycles [1] and also may represent the greatest potential genetic resource in the biosphere."