In a stunning twist that makes human ingenuity look a bit lazy, scientists at the University of Maryland have discovered that western diamondback rattlesnakes have been carrying around a superior antivenom in their blood all along. It's like finding out the cure for the common cold was in your fridge the whole time.
Led by Distinguished University Professor of Biology Sean B. Carroll, the research, published in the Proceedings of the National Academy of Sciences, reveals that the snakes evolved specific toxin-blocking proteins to protect themselves from venom - a natural defense system that puts our current treatments to shame.
"This is one of those great stories when nature has already solved a problem we've been grappling with for decades," said Carroll, who also holds the Andrew and Mary Balo and Nicholas and Susan Simon Endowed Chair at UMD. Because nothing says 'I've got this figured out' like borrowing from the very creatures that are biting you.
Snakebite is officially one of the world's most neglected tropical diseases, with venomous snakes killing an estimated 80,000 to 140,000 people annually. Hundreds of thousands more survive but are left with permanent disabilities. Many of these victims live in rural areas where effective antivenom is as scarce as a humble snake.
Current antivenoms are a bit of a relic, produced by injecting venom into large animals like horses or sheep and then harvesting their antibodies. This process is costly, inconsistent, and can cause nasty immune reactions. It's like using a sledgehammer to swat a fly - if the sledgehammer might also explode.
So, Carroll's team turned to the snakes themselves. "We've known from anecdotes for 100 years that vipers tend to be resistant to their own venom," he said. "But for a long time, nobody knew what exactly was circulating in their blood that protected them."
In 2022, they found part of the answer: a protein called FETUA-3, which blocks metalloproteinase toxins in rattlesnake venom. Now, they've gone further, examining how different FETUA proteins work together.
Individual proteins could counter certain effects - one might reduce bleeding, another might interfere with enzyme activity - but none alone could prevent death from a bite. However, when combined, the proteins became far more effective. In fact, optimized mixtures were about 10 times more potent than the current sheep-derived rattlesnake antivenom. Ten times! And they neutralized venom from multiple viper species, even those separated by millions of years of evolution.
Finding the right combinations is tricky because snake venom is a cocktail of about 100 different toxins. "The ingredients are there," Carroll said. "We just have to keep testing various mixtures."
One of the most reassuring findings? "The fact that parts of these inhibitors have been perfectly conserved over 50 million years of snake evolution tells you just how real a risk this is for these animals," Carroll noted. So, snakes have been perfecting this defense for eons - while we've been milking sheep.
The study focused on metalloproteinases, but the team is already targeting other toxin families. "We're getting remarkably close to having effective solutions for the three major toxin families in vipers," Carroll said.
But don't expect to see this in your local ER anytime soon. First, it'll likely appear in veterinary medicine, which is great news for dogs bitten by snakes. Human treatments might follow, with Carroll envisioning antivenoms that are safer, cheaper, and easier to produce on a massive scale.
"We could make train cars-worth of this stuff and help solve a massive global health problem," he said. "Many of our most important medicines have come from nature. I'm delighted that the components for a better-than-commercial antivenom were in these snakes all along."
So, the next time you're hiking and see a rattlesnake, remember: it's not just a threat, it's a walking pharmacy. Just maybe don't try to extract the antivenom yourself.
The research was funded by the Howard Hughes Medical Institute and the Viper Resource Center (Grant #P40OD01960-22). Materials provided by University of Maryland.