Scientists Discover Virus that Infects Other Viruses

One of the fundamental questions in science is "what is life?", a question particularly pertinent of late with the search for signs of life on Mars and the advances in developing synthetic life in a lab. Scientists have devised many complex answers to the question, but basically most scientists would agree that a "living" creature must be able to produce a variety of useful structural units (proteins), carry a genetic code (DNA), and reproduce.

Following this definition of life, viruses typically met the latter two tests, but failed the first as they only produced a few structural or protective proteins to encase themselves. This was a primary justification in classing them as nonliving. However, recent discoveries have troubled this comfortable notion of the solid boundary between life and nonlife. First, a variety of parasitic bacteria have been discovered, many of which lack the key protein enzymes needed to survive outside their host -- another bacteria.