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Crocodile blood may yield powerful new antibiotics

SYDNEY (Reuters) - Scientists in Australia's tropical north are

collecting blood from crocodiles in the hope of developing a

powerful antibiotic for humans, after tests showed that the

reptile's immune system kills the HIV virus.

The crocodile's immune system is much more powerful than that of

humans, preventing life-threatening infections after savage

territorial fights which often leave the animals with gaping wounds

and missing limbs.

" They tear limbs off each other and despite the fact that they live

in this environment with all these microbes, they heal up very

rapidly and normally almost always without infection, " said U.S.

scientist Mark Merchant, who has been taking crocodile blood samples

in the Northern Territory.

Initial studies of the crocodile immune system in 1998 found that

several proteins (antibodies) in the reptile's blood killed bacteria

that were resistant to penicillin, such as Staphylococcus aureus or

golden staph, Australian scientist Adam Britton told Reuters on

Tuesday. It was also a more powerful killer of the HIV virus than

the human immune system.

" If you take a test tube of HIV and add crocodile serum it will have

a greater effect than human serum. It can kill a much greater number

of HIV viral organisms, " Britton said from Darwin's Crocodylus Park,

a tourism park and research center.

Britton said the crocodile immune system worked differently from the

human system by directly attacking bacteria immediately an infection

occurred in the body.

" The crocodile has an immune system which attaches to bacteria and

tears it apart and it explodes. It's like putting a gun to the head

of the bacteria and pulling the trigger, " he said.

For the past 10 days Britton and Merchant have been carefully

collecting blood from wild and captive crocodiles, both saltwater

and freshwater species. After capturing a crocodile and strapping

its powerful jaws closed the scientists extract blood from a large

vein behind the head.

" It's called a sinus, right behind the head, and it's very easy just

to put a needle in the back of the neck and hit this sinus and then

you can take a large volume of blood very simply, " said Britton.

The scientists hope to collect enough crocodile blood to isolate the

powerful antibodies and eventually develop an antibiotic for use by

humans.

" We may be able to have antibiotics that you take orally,

potentially also antibiotics that you could run topically on wounds,

say diabetic ulcer wounds; burn patients often have their skin

infected and things like that, " said Merchant.

However, the crocodile's immune system may be too powerful for

humans and may need to be synthesized for human consumption.

" There is a lot of work to be done. It may take years before we can

get to the stage where we have something to market, " said Britton.