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Scientists have zoomed in on mimivirus, the enormous virus with the delicate name that has perplexed scientists since 1992, when it was found living in an amoeba in a water tower in England. “This is like landing on the moon,” says Michael Rossmann of Purdue University in West Lafayette, Ind. Rossmann and an international team of scientists report the results of their reconnaissance online April 27 in PLoS Biology. Mimivirus, full name Acanthamoeba polyphaga Mimivirus, is the largest known virus in the world. Its mass is more than 100 times that of the virus that causes the common cold, says...

Enlarge ImageBigger fleas have littler fleas. And Mimiviruses are infected with smaller Sputnik viruses.Credit: Courtesy of Bernard La Scola/URMIT Little more than protein capsules chock-full of genetic material, viruses barely rank among the living. Yet like people, at least one virus can catch a virus--the viral equivalent of coming down with the flu. This "flu" virus impairs the host virus's ability to grow and reproduce, a research team studying the largest known viruses reports. Viruses are tiny biological hijackers that cause diseases that include the common cold, the flu, chickenpox, and AIDS. They infect animals, plants, and microorganisms and...

Web address:     http://www.sciencedaily.com/releases/2008/05/     080531090353.htm Invasion Strategy Of World's Largest Virus Revealed enlarge (A) TEM image of cryo-fixed sectioned and stained extracellular Mimivirus particles revealing a star-shaped structure at a unique vertex. (B) Cryo-TEM image of a whole vitrified fiber-less Mimivirus. (C) SEM image of the star-shaped structure in a mature extracellular Mimivirus particle. (D) Cryo-SEM of an immature, fiber-less particle. (E) Tomographic slice of a mature intracellular Mimivirus particle captured at a late (12 h post infection) infection stage. As shown in Video S1, at this late stage the host cell is packed with mature viral particles. (F and G) Volume...

A monstrous discovery suggests that viruses, long regarded as lowly evolutionary latecomers, may have been the precursors of all life on Earth Few things on Earth are spookier than viruses. The very name virus, from the Latin word for "poisonous slime," speaks to our lowly regard for them. Their anatomy is equally dubious: loose, tiny envelopes of molecules—protein-coated DNA or RNA—that inhabit some netherworld between life and nonlife. Viruses do not have cell membranes, as bacteria do; they are not even cells. They seem most lifelike only when they invade and co-opt the machinery of living cells in order to...

French biologists have just mapped out the genetic sequence of the largest known virus, and the complexity of the thing has them questioning what it is. The genetic code of the mimivirus, as it is called, is three times longer than that of other viruses and contains elements that blur the lines between life and non-life. Whether viruses are alive has been a matter of debate for more than half a century. They are often thought of as merely complex "biomolecules" – lifeless capsules of genetic information that must invade a living cell and hijack its machinery to reproduce. The...