Snake bites affect approximately 1.8 million people annually. The current standard of care is antibody-based antivenom, but it can be difficult to obtain and is generally ineffective against local tissue damage. New research suggests that heparin, a commonly used blood-clotting inhibitor, could be repurposed as an inexpensive antidote for cobra venom.

“Our findings have the potential to significantly reduce the horrific necrotic injury caused by cobra bites, and may also slow the release of venom and improve survival rates,” Professor Greg Neely, from the University of Sydney, said.

The authors identified a way to block cobra venom using CRISPR gene editing technology and showed that heparin and related drugs could be repurposed to prevent necrosis caused by cobra bites.

“Heparin is cheap, ubiquitous and listed as an essential medicine by the World Health Organisation,” says Tian Du, a PhD student at the University of Sydney.

“If the human trials are successful, it could be used relatively quickly as a cheap, safe and effective drug to treat cobra bites.”

Using CRISPR, researchers have discovered the human gene required for cobra venom to kill flesh at the bite site.

One of the desired venom targets is an enzyme needed to make heparan and heparin, related molecules produced by many human and animal cells.

Heparan is present on cell surfaces and heparin is released during immune responses, and because of their similar structure, toxins can bind to either.

Scientists have used this knowledge to create an antidote that can stop necrosis in human cells and mice.

Unlike current cobra bite antivenoms, which are 19th century technology, heparinoids act as a “decoy” antidote.

The antidote works by injecting large amounts of “decoy” heparin sulfate or related heparinoid molecules into the bite site, which are able to bind to and neutralize the toxins in the venom that cause tissue damage.

“Our findings are intriguing because current antivenoms are largely ineffective at treating severe, localised poisoning which causes painful, progressive swelling, blistering and tissue necrosis around the bite,” said Professor Nicholas Casewell, from the Liverpool School of Tropical Medicine.

of study Published in the journal Science Translational Medicine.

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Tian Y. Du others2024. Molecular dissection of cobra venom highlights heparinoids as potential antidotes to spitting cobra venom. Science Translational Medicine 16 (756); doi: 10.1126/scitranslmed.adk4802