Opossums may save you from deadly snake bites

Scientists have turned to the opossum - a small to medium-sized marsupial - to develop a promising and inexpensive antidote for venomous snake bites.
Worldwide, an estimated 421,000 cases of venomous snake bites and 20,000 deaths from these bites occur yearly, according to the International Society on Toxicology.
Opossums shrug off snake bite venom with no ill effects. Claire F Komives at San Jose State University explained that initial studies showing the opossum's immunity to snake venom were done in the 1940s.
In the early 1990s, a group of researchers identified a serum protein from the opossum that was able to neutralise snake venoms.

One researcher, B V Lipps, found that a smaller chain of amino acids from the opossum protein, called a peptide, was also able to neutralise the venom.
However, it appeared that no one followed up on those studies to develop an antivenom therapy.

Armed with this information, Komives and colleagues had the peptide chemically synthesised.
When they tested it in venom-exposed mice, they found that it protected them from the life threatening effects of bites from US Western Diamondback rattlesnakes and Russell's Viper venom from Pakistan.
The exact mechanism is not known, but recently published computer models have shown that the peptide interacts with proteins in the snake venom that are toxic to humans, Komives said.

"It appears that the venom protein may bind to the peptide, rendering it no longer toxic," Komives added.
Komives' team showed that they could programme the bacteria E coli to make the peptide. Producing the peptide in bacteria should enable the group to inexpensively make large quantities of it.
The peptide should also be easy to purify from E coli.
"Our approach is different because most antivenoms are made by injecting the venom into a horse and then processing the serum," said Komives.
"The serum has additional components, however, so the patient often has some kind of adverse reaction, such as a rash, itching, wheezing, rapid heart rate, fever or body aches. The peptide we are using does not have those negative effects on mice," Komives said.

The antivenom would probably work against venoms from other venomous snakes, as well as against scorpion, plant and bacterial toxins.
The new antivenom has another potential advantage: It likely could be delivered in just one injectable dose, researchers said.
The research will be presented at the 249th National Meeting & Exposition of the American Chemical Society (ACS) in Denver.