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A snakebite antivenom made from snake blood, about 10x more potent than the sheep-derived standard

A University of Maryland team led by Sean B. Carroll reports that a cocktail of proteins drawn from snake blood itself was about 10 times more potent than the current sheep-derived antivenom in lab tests, and neutralized venoms from multiple viper species at once.

biology

— 4 mins read

Every year, somewhere between 80,000 and 140,000 people die from snakebites — a toll almost entirely concentrated in the rural tropics and almost entirely preventable, if the antivenom actually existed in the right form at the right moment. A study published today, July 29, in PNAS from a University of Maryland-led team, points at one plausible fix: pull the venom-neutralizing proteins straight from the snakes themselves, in the form of compounds circulating naturally in snake blood.

The lead author is Sean B. Carroll, a molecular biologist at UMD whose lab has spent years documenting how venomous animals protect themselves from their own toxins. The new paper reports that a cocktail of two snake-blood proteins called fetuins — the FETUA combination — fully neutralized the lethality of western diamondback rattlesnake venom in lab tests. According to the University of Maryland release, the optimized combination was about 10 times more potent than the current sheep-derived rattlesnake antivenom when matched dose for dose.

That figure is striking, but the more interesting part is the breadth. Viper venoms vary enormously across species and across the dozens of millions of years of evolution separating them, which is the structural reason existing antivenoms tend to be narrow and regional — antibodies raised against one snake’s venom cocktail don’t necessarily recognize another’s. The Carroll team’s protein mix, SciTechDaily reported, neutralized not just rattlesnake venom but venoms from multiple other viper species separated by tens of millions of years of evolution. Carroll himself noted that the relevant inhibitors have been conserved across roughly 50 million years of snake evolution, which is why a small set of proteins from one species reaches so far.

One small wrinkle in the coverage is worth flagging on the potency comparison itself. The UMD press release and News-Medical’s reporting describe the cocktail as roughly 10 times more potent than the generic “current sheep-derived rattlesnake antivenom,” while SciTechDaily specifies the same comparison as “up to 10 times more potent by weight than commercial CroFab antivenom.” CroFab is in fact the leading sheep-derived antivenom used for North American pit viper bites, so the two characterizations are not in conflict — the second is just naming the specific product the first is gesturing at. The order-of-magnitude figure holds either way.

What the paper does not yet show is whether the snake-blood approach will translate into a usable drug. The 10x potency number comes from in vitro neutralization assays — venom mixed with the protein cocktail, then tested for residual lethality — which is the standard early benchmark in the antivenom field but a long way from clinical evidence in bitten patients. Manufacturing is its own question too: producing the proteins recombinantly at scale is straightforward in principle, but the existing antivenom industry is built around a century of infrastructure for raising immunized sheep and purifying their antibodies, and any replacement has to clear the same regulatory and cold-chain hurdles.

Still, the underlying logic is appealing for reasons that go beyond this one paper. A sheep-derived antivenom works because injected antibodies happen to bind venom toxins; a snake-blood-derived one works because the donor animal evolved in constant, intimate contact with that exact class of toxins and keeps a dedicated circulating defense against them. The same source that reported the 10x figure noted that the protective inhibitors have been conserved for roughly 50 million years, meaning the relevant biochemistry already exists, fully refined by natural selection, waiting in the blood of every viper on the planet. Using it directly is a more obvious move than it sounds like at first, and the UMD result is the strongest evidence yet that it actually works.

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