Alligators are more likely to make people think of life-threatening injuries than new ways of healing. But researchers in Louisiana have found that alligators - and their unusual immune system - may one day help us in our fight against serious infections, as Véronique LaCapra reports.

Proteins from the blood of American alligators (Alligator mississippiensis) could provide a powerful new source of antibiotics for fighting human infections

Growing up hunting and fishing in the swamps of Louisiana and Southeast Texas, Mark Merchant was around a lot of alligators. Now an Associate Professor of Biochemistry at Louisiana's McNeese State University, he still has a strong admiration-and respect-for these fiercely territorial predators.

"Alligators are very aggressive animals and they in engage in a lot of fighting," he explains. "During these fights they sometimes can inflict serious injury on each other, including loss of entire limbs."

Alligators spend their lives in wetlands, in what amounts to a marshy soup of bacteria, so you might think that wounded animals would be prime targets for infection. But speaking on a mobile phone from Argentina, where he is doing research, Merchant says that's not the case. "Despite the fact that they live in an environment which is very conducive to infection, they heal most often without any signs of infection and quite rapidly in fact."

The surprising healing abilities of alligators prompted Merchant to look more closely at their immune system. "One of the things that we're very excited about is that we think that we have some very strong evidence that their white blood cells are producing [...] small proteins that have some pretty incredible antibiotic and antifungal activities."

Lancia Darville, a graduate student at Louisiana State University and a collaborator on Merchant's research, describes one of his early experiments: "He was able to take alligator blood and expose it to various strains of bacteria - 23 different strains of bacteria to be specific - and he found that all 23 […] were depleted."

When Merchant performed the same experiment using human blood, he found that only eight of the 23 strains of bacteria were depleted. "A good indication," says Darville, "that the alligators had different proteins present that we as humans don't have."

Darville has been working on the next step in this research: "to separate and identify the antimicrobial proteins that are present in the American alligator that are causing them to have such a high innate immune system."

By isolating these proteins, and determining their chemical structure, Merchant and Darville hope they can ultimately be used to develop new antibiotics for human use.

For example, the proteins could be used in antibiotic creams for treating foot ulcers in diabetics, or preventing infections in burn patients. If all goes well, alligator-based medications could be available for human use in seven to ten years.

Darville says the alligator proteins also show promise for combating viruses. "Long term," she explains, "Dr. Merchant is suggesting that these blood proteins may also be used to fight off the HIV virus, which is the virus that causes AIDS."

Darville presented their research on April 6th, at the national meeting of the American Chemical Society.