State scientists and regulators mobilized against the threat, known as white spot syndrome virus. They destroyed tons of farm-raised shrimp, launched field surveys and lab studies and took extreme measures to sterilize the state-owned Waddell Mariculture Center in Bluffton.

"We nuked it," joked Bob Chapman, a S.C. Department of Natural Resources research scientist at the Hollings Marine Laboratory.

Then came the twist: In May 1997, state DNR researchers announced that the same white spot virus they'd found in shrimp farms that winter was turning up practically everywhere they looked. They found it in wild shrimp, in crabs, in a wide array of tiny animals, maybe even floating freely in the water itself.

Chapman provided the next surprise: He found genetic evidence in 10-year-old tissue samples from crabs that suggested the virus had been hanging around the Lowcountry since at least 1988.

"All of which means it's probably been there for a long time," said Paul Sandifer, a former state scientist who now works for the National Oceanic and Atmospheric Administration.

Today, seven years removed from the original crisis, the white-spot scare of 1997 looks like a stroke of remarkably good luck: It generated significant research funding, gave birth to the field of marine genomics, improved scientists' ability to manage disease in shrimp farms and set in motion a series of discoveries that someday could produce new classes of disease-fighting drugs for humans.

AND LIKE SO MANY SCIENTIFIC SUCCESS STORIES, THIS ONE REALLY BEGINS WITH A GRADUATE STUDENT WHO LOOKED AT HIS LAB RESULTS ONE DAY AND SAID, "WELL, THAT'S FUNNY."ANCIENT IMMUNITY

Not so very long ago, biologists operated under the assumption that shrimp and other invertebrates somehow got by without any immune system at all. They were wrong: Invertebrate immunity just doesn't work quite like ours.

Human immunity is actually a series of interlocking systems, some with roots deep in our evolutionary past. The best known is the antibody-producing adaptive immune system, but the unsung hero in the war against microbial invasion is called innate immunity. When challenged, this system confronts foreign microbes with specialized cells and germ-fighting proteins. According to Gregory Warr, a biochemist at the Medical University of South Carolina, innate immunity successfully handles 99.9 percent of our microbial interactions.

Adaptive immunity only rides to the rescue when the frontline defenses of innate immunity fail. It offers a variety of powerful responses to threats such as bacteria and fungi, but adaptive immunity really shines in the fight against our trickiest infective foe: viruses.

Viruses are small (the common cold virus is about 1/100th the size of an E. coli bacteria), highly adaptive and don't even fit our standard definition of a living organism. That's because they don't reproduce: Instead, a virus hijacks the chemical machinery inside a host's cells and makes them churn out copies. To attack a virus, the body must literally attack itself.

Making matters worse, viruses mutate so quickly that it's not uncommon for a new strain to arise in less time than it takes for scientists to find a way to attack the old one. "We're always in a race with this," said Chapman.

That's why the HML team focused on the shrimp's response rather than the virus itself.

The discovery of latent white spot syndrome virus in native waters immediately challenged old thinking about invertebrate immunity. Virtually every shrimp in the Lowcountry carried it, yet there was no evidence that it was affecting the wild population.

But what was keeping those shrimp alive?

The breakthrough at Hollings Marine Lab began unexpectedly. Graduate student Javier Robalino had been conducting an experiment on shrimp in which he used a viral byproduct to attack immunity-related genes, then exposed the shrimp to the actual virus. The shrimp should have died faster because their immune systems had been suppressed.

Only, the shrimp didn't die faster. In fact, most of them didn't die at all.

Nor did it matter what form of the viral byproduct researchers applied: The mere presence of double-stranded RNA appeared to boost the shrimp's resistance. Instead of weakening the animals, it appeared to be immunizing them.

In follow-up tests, Hollings Marine Lab scientists found that low-level exposure to dsRNA increased a shrimp's chance of surviving a viral infection by 50 to 75 percent. The discovery pointed to what Chapman called a cryptic system of viral immunity.

The existence of such a system was exciting news, though its details await discovery. "Basically," said crustacean biologist Paul Gross, "all we know is that there is an immunity."

But that's huge, according to Sandifer. "The immediate payoff may be that we figure out how to control shrimp disease, ... but when you look at the longer-range implications, it's really striking."

One of the more intriguing possibilities involves tiny chains of common proteins known as antimicrobial peptides, or AMPs.

Unrelated clinical trials suggest AMPs could be used effectively in a variety of human disease-fighting medications. But there's something special about AMPs that makes instant sense to anyone who has ever struggled to fight off a persistent infection: Unlike antibiotics, there's no evidence yet that diseases develop resistance to AMPs.

BRING IT HOME

Obviously, shrimp and people don't have a whole lot in common. A virus that attacks one species is typically no threat to the other. So why all the fuss?

One not-so-obvious answer is that nature doesn't reinvent the wheel. Successful developments in biochemistry tend to be conserved, appearing in multiple species. For example, after the discovery of a chemical receptor that activates the immune system in fruit flies, scientists went looking for something similar in humans -- and found it. The structures, called Toll-like receptors, have been adapted to a couple of different jobs in humans, but the efficient biochemical "conveyor belt" that drives them remains basically unchanged despite millions of years of evolution.

Such unexpected connections lie at the heart of the federal government's Oceans and Human Health Initiative, a new approach to marine research that emphasizes the practical payoffs of such studies. The OHHI umbrella covers traditional environmental studies, but also topics such as toxic algal blooms and marine genomics.

There's no sign at the gate commemorating the event, but Fort Johnson is the birthplace of marine genomics. The science got its start here about five years ago with Chapman, and today his international marine genomics mailing list counts 55 members. Though immensely promising, the field remains in its infancy, and despite all their progress, team members have only deciphered about 10 percent of shrimp DNA.

So when five scientists with a stake in the project sit down to talk about their work, simple questions spawn lengthy discussions. What's different about this "cryptic system"? What gene controls it? How might it be related to our own? Ideas flash back and forth across the table as the scientists cite unpublished studies and challenge each other's assumptions.

It makes Craig Browdy, a senior marine scientist at DNR's Marine Resources Research Institute, laugh. "This sounds an awful lot like a lab meeting," he said.

Warr shrugs. "We're on the cutting edge here. You always get these disputes."

The disagreements are collegial and telling: The Hollings Marine Lab is a multiagency facility, and in true HML style, the five men around the table come from diverse backgrounds. Chapman, considered the "founding father of marine genomics," is a state DNR scientist. Warr, an MUSC biochemist, came to genomics late in his career. Despite his specialty as a crustacean biologist, Gross is actually an assistant professor on the MUSC faculty. Browdy is a hands-on shrimp-farming expert with the state's mariculture program in Bluffton. Sandifer is a former executive director of the DNR's Fort Johnson lab who now holds the title of NOAA senior scientist. A sixth partner, Eric Lacy of MUSC, runs the medical school's Marine Biomedicine and Environmental Sciences Center.

All six are quick to share credit, perhaps because so much of their program depends on sharing resources. Their efforts have attracted about $4 million in grant funding, most of it federal. While the state hasn't picked up any of the bill, the group points out repeatedly that it wouldn't even be here, as Gross said, "if South Carolina had not had the foresight to build a strong research component."

Chapman suspects their research could lead to insights on how organisms develop from embryos and the treatment of genetic diseases. You just never know.

"Whenever you start to understand a basic process," he said, "you get amazed by how it works and what spins out of it."