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Giving Termites a Lethal Bug

April 16, 2003

Heather Heilman

hheilman@tulane.edu

New Orleans is the center of the Formosan termite invasion that is spreading across the southern United States. Although more than a billion dollars are spent every year to prevent infestation or to repair the damage once it's done, the bugs continue to claim new territory. And no one has been able to get rid of a colony once it's established.

"Chemical agents can kill the ones that are exposed, but they don't always get to the root of the problem, which is underground," said Sharon Isern, research assistant professor of tropical medicine. "Termites have a fantastic ability to protect themselves. If a termite is sick it will leave the colony and the other termites will wall it off, basically burying it alive. There's very little contact between sick termites and healthy termites."

Isern is a virologist with a background in designing vectors used to deliver gene therapy. Because of her interest in retroviruses and how viruses can be modified, she applied for and received a grant from the National Science Foundation to study virus entry into a number of different invertebrate organisms, including sponges, hydra, microcrustaceans and termites.

Because termites were on the agenda, she found herself involved in an endeavor by the U.S. Department of Agriculture and the Tulane-Xavier Center for Bioenvironmental Research to develop a method of termite biocontrol.

"The idea is to find a naturally occurring virus that's already in the termites or some other invertebrate that will kill termite cells and not, say, mammalian cells," Isern said.

She's just received another grant to develop methods for introducing genes into termite cells. Working in collaboration with the Formosan termite research unit at the U. S. Department of Agriculture's Southern Regional Research Institute in New Orleans, Isern's lab will make a sterile culture of termite cells from termite eggs and then use those cells to find pathogenic termite viruses.

"We'll isolate the infected cells and try to propagate the virus," she said. "Then we'll use these viruses to infect other termite cells and see which viruses actually cause cell death."

Using a virus that's already out there would be preferable to biocontrol approaches that involve designing a new virus or otherwise genetically altering organisms, Isern said.

"We don't want to genetically engineer a new virus and put it out there. We're trying to get rid of an invasive species; we don't want to introduce a new one."

If she finds a virus that kills termites without harming other things, it could be used in a baiting system that could potentially get rid of a whole colony of termites. Since the bugs wouldn't know they were infected, their normal defense mechanisms would be bypassed. But a new method of controlling termites, if one emerges, would be a byproduct of Isern's greater project of studying invertebrates and the viruses that infect them.

"I believe that by studying these really basic organisms we're going to get a lot of basic information that can be used down the road in medicine," she said.

Heather Heilman can be reached at hheilman@tulane.edu.

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