Every year thousands of people die in the world due to cobra bites and many others – probably in the order of a hundred thousand, according to experts’ estimates – remain severely mutilated by necrosis caused by their venom, which can lead to amputation. Cobras continue to top the list of global fears. Rightly so. Also because there are few weapons to fight them. But perhaps the cards on the table could change a little. A team of scientists from the University of Sydney and the Liverpool School of Tropical Medicine has in fact discovered a new antidote for the bites of this family of dangerous snakes. And it is also ‘low cost’. The new antidote is an old drug: heparin.
Why do the authors not hesitate to call it “a remarkable discovery”? Because the current antidote treatment is expensive and does not effectively treat the necrosis of the flesh at the site of the bite, they explain. While heparin is a commonly used, cheap and widely available anticoagulant, and the results of the research that earned the cover of ‘Science Translational Medicine’, it appears that it could also be repurposed as a low-cost antidote against cobra venom.
Why the discovery is remarkable
This discovery “could dramatically reduce the horrific necrotic wounds caused by cobra bites and may also slow down the venom, which could improve survival rates,” says corresponding author Greg Neely, of the Charles Perkins Centre and the Faculty of Science at the University of Sydney.
Using Crispr gene-editing technology to find the human genes that cobra venom needs to cause necrosis and identify ways to block it, the team of experts from Australia, Canada, Costa Rica and the UK focused on heparin and related drugs, and showed that they could stop the necrosis caused by the bite.Heparin is ubiquitous and an essential medicine. listed by the World Health Organization (WHO),” notes lead author Tian Du, also of the University of Sydney. “After successful human trials, it could be distributed relatively quickly and become a cheap, safe and effective drug for the treatment of cobra bites.”
What scientists have discovered is that one of the targets required by the venom is the enzymes needed to produce the related molecules heparan and heparin, which are produced by many human and animal cells. Heparan is found on the cell surface, and heparin is released during an immune response. The venom can bind to both. Heparinoid drugs act as a ‘bait’: by flooding the bite site with heparinoid molecules, the antivenom can bind to and neutralize toxins in the venom that cause tissue damage.
“Snakebites remain the deadliest of the neglected tropical diseases, and their impact falls overwhelmingly on rural communities in low- and middle-income countries,” said Nicholas Casewell, Liverpool School of Tropical Medicine. “Our findings are exciting because current antivenoms are largely ineffective against severe local envenomation, which involves painful, progressive swelling, blistering and tissue necrosis around the bite site. This can lead to loss of limb function, amputation and permanent disability.”
WHO has identified snakebite as a priority in its agenda to address neglected tropical diseases and announced an ambitious target to reduce the global burden of snakebite by half by 2030. “That goal is now just five years away,” Neely concluded. “We hope that the new cobra antivenom we have discovered will contribute to the global fight to reduce snakebite mortality and injuries in some of the world’s poorest communities.”
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