Ebola and the Vast Viral Universe Behind the hellish Ebola epidemic ravaging West Africa lies an agent that fittingly embodies the mad contradictions of a nightmare. It is alive yet dead, simple yet complex, mindless yet prophetic, seemingly able to anticipate our every move. For scientists who study the evolution and behavior of viruses, the Ebola pathogen is performing true to its vast, ancient and staggeringly diverse kind. By all evidence, researchers say, viruses have been parasitizing living cells since the first cells arose on earth nearly four billion years ago. Some researchers go so far as to suggest that viruses predate their hosts. That they essentially invented cells as a reliable and renewable resource they could then exploit for the sake of making new viral particles. It was the primordial viral “collective,” said Luis P. Villarreal, director of the Center for Virus Research at the University of California, Irvine, “that originated the capacity for life to be self-sustaining.” “Viruses are not just these threatening or annoying parasitic agents,” he added. “They’re the creative front of biology, where things get figured out, and they always have been.” Researchers are deeply impressed by the depth and breadth of the viral universe, or virome. Viruses have managed to infiltrate the cells of every life form known to science. They infect animals, plants, bacteria, slime mold, even larger viruses. They replicate in their host cells so prodigiously and stream out into their surroundings so continuously that if you collected all the viral flotsam afloat in the world’s oceans, the combined tonnage would outweigh that of all the blue whales. Not that viruses want to float freely. As so-called obligate parasites entirely dependent on host cells to replicate their tiny genomes and fabricate their protein packages newborn viruses, or virions, must find their way to fresh hosts or they will quickly fall apart, especially when exposed to sun, air or salt. “Drying out is a death knell for viral particles,” said Lynn W. Enquist, a virologist at Princeton. How long shed virions can persist if kept moist and unbuffeted — for example, in soil or in body excretions like blood or vomit — is not always clear but may be up to a week or two. That is why the sheets and clothing of Ebola patients must be treated as hazardous waste and surfaces hosed down with bleach. Viruses are masters at making their way from host to host and cell to cell, using every possible channel. Whenever biologists discover a new way that body cells communicate with one another, sure enough, there’s a virus already tapping into exactly that circuit in its search for new meat. __________________________________________________________________ Source : N.Y Times
Posted on: Tue, 28 Oct 2014 12:45:28 +0000
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