Human serum destroyed only eight of the bacterial strains. But the alligator serum killed all 23, including drug-resistant bacteria such as MRSA (methicillin-resistant Staphylococcus aureus).
(Related news: "Drug-Resistant Bacteria Found in Wild Arctic Birds" [January 24, 2008].)
When the alligator serum was exposed to HIV the researchers found that a good amount of the virus was destroyed.
The study team thinks that pills and creams containing alligator peptides could be available at local pharmacies within seven to ten years.
Such products would be a boon to patients that need extra help preventing infections, such as diabetes patients with foot ulcers, burn victims, and people suffering from auto-immune diseases.
But there may be potential hurdles before alligator-based medicines can reach drugstore shelves.
For example, Darville noted, initial tests have revealed that higher concentrations of the alligator serum tend to be toxic to human cells.
Not So Primitive
Adam Britton is a biologist based in northern Australia who has found similar antimicrobial proteins called crocodillins in the blood of crocodiles.
Antimicrobial peptides in crocodiles and alligators are part of the animals' innate immune systems, Britton said, which provide automatic protection from certain diseases.
By contrast, human immunities are adaptive—people develop resistance to many diseases after exposure, such as the low doses given in vaccines.
Although innate immunity is often considered primitive, there is nothing primitive about its effectiveness, Britton said.
Innate immunities "usually serve to amplify the adaptive immune system, often by weakening the membranes of bacteria," he said.
"It appears that alligator and crocodile antimicrobial peptides are extremely effective agents" against bacteria, he added.
Britton hopes to use Australian crocodile blood to complement the latest work on alligators and answer questions about what these proteins mean for immune systems in general.
"If we can harness these secrets," Britton said, "we could be on the verge of a major advance in medical science."
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