Virus hunter. Marilyn Roossinck at Ardmore, Oklahoma. (© 1999 Fred Powledge.)
A bad rap: Until recently, viruses have been known to science and medicine (and certainly to the general public) almost exclusively as troublemakers. A document from an agricultural cooperative extension agency in the United States, for example, starts off its discussion of the creatures with the statement, “Viruses are submicroscopic entities capable of causing disease.”
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Marilyn
J. Roossinck
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As
the world learns more about itself, biodiversity takes on a broadened
definition. It no longer mean only whales and pandas 
— the “cuddlies and fuzzies,” as some put it, or the “charismatic
megafauna,” in the words of others. Biodiversity means pretty much everything,
including our less charming neighbors — the worms and warthogs, kudzu
and cockroaches. But viruses? The things that make us feel awful, keep
us home from work or school, that kill plants and sicken livestock? Marilyn J. Roossinck is happy to invite viruses into biodiversity’s dominion. She professes to love viruses and is on record as thinking they’re “neat.” She also believes that science has lived far too long in ignorance of the viral world, and she wants to do something about it. The Biodiversity Leadership Award winner wants to build an inventory of the viruses that affect plants — or at least start building one, for the task is enormous. Roossinck is beginning with a tablet that is nearly blank: What science knows about viruses can practically be written on the head of a pin, with room for several viruses left over. For starters, scientists don’t have a firm definition of what a virus actually is. Almost always, they are referred to in negative terms; AIDS and Ebola, after all, are the products of viruses. Usually, viruses are described as entities whose genetic constituents are nucleic acids that become most active when they penetrate other entities. Most definitions refer to viruses as “infectious agents” of some sort — microscopically tiny, simple in structure, and essentially dormant until they get inside a living cell of another organism. Once they’re in, they are capable of producing new virus particles rapidly. And they can do all of this in enormous numbers: There are about 6 billion people on Earth; “You could have that many viruses in a few cells” of a plant or animal, Roossinck says. Why all the ignorance? And why are we so uninformed about viruses? One answer is that viruses are so small, and molecular biology has only recently created tools that let researchers probe into their personalities. But Roossinck also thinks it’s because viruses have such a bad reputation. Science, particularly medical and agricultural science, has focussed its attention on the viruses that cause disease. A strictly negative attitude about viruses, thinks Roossinck, is proof that “we don’t know anything about the rest of the virus world. For example: When scientists started doing tissue culture and discovered simian viruses [viruses that infect monkeys and other primates] their findings were numbered, starting at SV-1, and they went up to somewhere around SV-50. Of those, there was one that caused tumors — SV-40 — and that’s the only one that anyone’s ever heard of. The others didn’t cause any disease, so they were never studied. “In humans we have described around two hundred and fifty viruses, most of which cause disease. If that simian virus scenario is an accurate picture of the ratio of disease-causing viruses to harmless viruses, well, in humans there could be as many as twenty thousand viruses. I don’t think that’s an unreasonable guess. But we just have no idea, because we have no data.” [To Roossinck Page 2] |
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