Miami Herald - May 29, 2008
Curtis Morgan, cmorgan@MiamiHerald.com

Scientists in Louisiana recently found the blood of the American alligator such a potent killer of bacteria, including some resistant to existing antibiotics, that they are hoping to use it to develop new medicines.

Researchers at Louisiana State University and McNeese State University stress it will take years to tell whether reptile extracts would even work in the human bloodstream. Some skeptics, including experts at the University of Florida, aren't enthused about the prospects for pharmaceutical gator aid.

But study co-author Mark Merchant, an assistant professor of biochemistry at McNeese State, sees promise in decoding the alligator's primitive but powerful immune system. He believes the reptiles, which date to the twilight of the dinosaur age 80 million years ago, have built biological defenses against infections to survive mangling and maiming caused by territorial and mating battles.

"Humans don't rip each other's legs off. Alligators live a very aggressive lifestyle -- they have put this evolutionary pressure on themselves," said Merchant, who has studied alligators for decades. "What we may see come out of crocodilian species is going to be different and perhaps better than things we have seen before."

Before ordering up a quart of miracle healing elixir from the local gator farm, however, consider that raw animal blood, whether from gator or goat, can make humans sick -- or worse.

Researchers use vials of blood drawn from living gators to isolate and extract active antibodies, a handful of proteins called peptides, in infection-fighting white blood cells. Study co-author Lancia Darville, a doctoral student in analytical chemistry at LSU, said the goal is to study how the material works and then synthetically duplicate it for drug development.

"Obviously, we can't just give alligator serum to humans," Darville said. "The body is going to reject anything it detects as foreign."

BACTERIA KILLER

In the study, which Darville presented in April at an American Chemical Society conference in New Orleans, the scientists reported proteins extracted from gator blood killed about two dozen strains of bacteria, including E. coli, strep and salmonella. It also handled a sometimes deadly form of staph skin infection and three other "super bugs" the U.S. Centers for Disease Control considers resistant to many existing antibiotics.

The gator proteins, they said, fought three times as many of the bacteria that human blood did. It also worked well on West Nile virus and HIV, Merchant said.

Merchant cautioned that doesn't necessarily make gator blood a candidate to be an AIDS drug. Bleach will do the same thing in a petri dish, he said. In high concentrations, Darville said, gator blood also killed not just the virus but the surrounding cell, which isn't good.

While agreeing the research has potential, two University of Florida experts said initial media reports overhype its possibilities.

"I don't see any reason to think the blood of reptiles has any special anti-microbial properties that we should all get really excited about," said Daniel Brown, a professor of infectious diseases in veterinary medicine at UF.

'SCANTY DATA'

Brown said he was skeptical about the key premise that alligators have some sort of super immunity. Observations of legless but otherwise healthy gators are mostly anecdotal, supported, he said, by "scanty data."

Brown said his research into mycoplasma, a bacteria that ravaged a gator farm in 1995, showed the creatures have all kinds of bacteria in their blood and can succumb to infections as other animals do.

"No one is out there examining 1,000 alligators every month, year after year, and assessing what injuries they sustained and what infections they developed," Brown said. "Their immune systems basically contain the same elements of defense against infection that mammals and birds and other reptiles have."

Although Lou Guillette, a distinguished professor of zoology at UF who has studied the debilitating impacts of pesticides and fertilizers on gators, also has doubts about unique curative properties, he said, "I am not completely convinced nothing is there."

"If you are exposed to certain bacteria on a regular basis, your body's immune system is prepared for it, reacts rapidly and minimizes the infection," Guillette wrote in an e-mail. "Given that, I also have been amazed that gators missing limbs, etc., are not dead from infections as they swim around in the swamp."

The Louisiana researchers expect it could take seven to 10 years before any resulting drug, perhaps in cream or pill form, could be ready.

They acknowledge hurdles ahead. Gator proteins could produce side effects or even prove toxic. Tests on cultured human cells will be a major hurdle. Other antibiotics developed from animals also are in the works but have not yet been cleared by federal regulators for testing on people.

Merchant sees a potential use for natural gator blood -- replacing tetracycline in hog feed, a practice studies indicate is spawning drug-resistant bacteria.

"I don't want to put forth that alligators are immune to any kind of infection," he said. "They do seem to me much more resistant. Every one heals themselves. They heal from nasty wounds in the marsh without infections, which is kind of a hallmark."

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