BLOOD BATTALION. Alligator blood harbors proteins that show promise for fighting several disease-causing microbes, including methicillin-resistant bacteria.U.S. Fish & Wildlife Service

Researchers hunting for new antibiotics might get some aid from gator blood. Scientists are zeroing in on snippets of proteins found in American alligator blood that kill a wide range of disease-causing microbes and bacteria, including the formidable MRSA or methicillin-resistant Staphylococcus aureus.

Previous experiments have revealed that gator blood extract cripples many human pathogens, including E. coli, the herpes simplex virus and some strains of the yeast Candida albicans. The serum's antimicrobial power probably derives from protein bits called peptides. Widespread among reptiles and amphibians, several such germ-fighting peptides have been isolated from the skin of frogs in recent years.

Many of these critters live in "sort of nasty places" that are polluted, and gators probably eat all kinds of sick animals, comments Paul Klein, a reptile infectious disease specialist at the University of Florida College of Medicine in Gainesville. Fierce battles with prey and other gators can leave gaping flesh wounds—but the animals are fairly hardy. These peptides provide a first line of defense—important in the lower vertebrates, who have a slower antibody response than humans, says Klein.

"It seems Mother Nature has built in a circulating system of antimicrobial factories that protect the animals while they are waiting to develop the cell-mediated response that we would develop quickly," he says.

Fishing around in the reptile's blood, the scientists identified four or five super-active peptides, reports chemistry doctoral student Lancia Darville of Louisiana State University in Baton Rouge. She collaborated with LSU chemist Kermit Murray and with Mark Merchant of McNeese State University in Lake Charles, La., and presented the work in New Orleans April 6 at a meeting of the American Chemical Society.

While alligators' immune response is mighty in some regards—they rarely develop tumors, for example—the beasts are by no means immune to all ills, notes Elliott Jacobson of the University of Florida College of Veterinary Medicine in Gainesville. Thirty-three alligators died and 13 more were euthanized when an epidemic caused by mycoplasma, the bacterial group responsible for pneumonia, swept through a gator farm in Florida in 1995. Later dubbed Mycoplasma alligatoris by Jacobson's colleague Daniel Brown, the previously unidentified bacteria quickly kill their reptilian hosts. "There are unique proteins in amphibians as well," says Jacobson. "But those animals are in a major decline due to diseases."

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