. . "A bacteriophage /\u02C8b\u00E6k\u02C8t\u026A\u0259r.i.o\u028A\u02CCfe\u026Ad\u0292/ (informally, phage /\u02C8fe\u026Ad\u0292/) is a virus that infects and replicates within a bacterium. The term is derived from \"bacteria\" and the Greek: \u03C6\u03B1\u03B3\u03B5\u1FD6\u03BD (phagein), \"to devour\". Bacteriophages are composed of proteins that encapsulate a DNA or RNA genome, and may have relatively simple or elaborate structures. Their genomes may encode as few as four genes, and as many as hundreds of genes."@en .