IISc and Denmark's DTU Create Nanobody Antivenom That Protects Mice From Indian Cobra Venom

India records nearly 50,000 snakebite deaths every year, the highest toll of any country in the world. Researchers at the Indian Institute of Science (IISc) in Bengaluru and the Technical University of Denmark (DTU) have now developed a new antivenom that protected mice against venom from several Indian cobra and king cobra species, offering a possible path to safer, more effective snakebite treatment. The study was published in the journal Science Translational Medicine.

Snake venom is a complex mixture of toxins that can damage the nervous system, blood and tissue, and its composition varies between species and regions, which makes a single broad-coverage antivenom hard to design. Conventional antivenoms, made for more than a century by immunising horses and extracting antibodies from their blood, can vary between batches, cause side effects, and yield only limited amounts of effective antibodies.

Kartik Sunagar of IISc's Centre for Ecological Sciences and Andreas Laustsen of DTU led the work, developing five small antibody fragments called nanobodies that bind to venom toxins and stop them from attaching to their targets in the body. "Antivenom treatment has virtually not changed for over 100 years," Sunagar said, describing the work as a next-generation approach to India's snakebite burden. The nanobodies were adapted from camelid antibodies earlier developed against African snake venoms, obtained from immunised alpacas and llamas and reproduced in microbial cells.

In tests, the nanobody cocktail protected mice injected with venom from spectacled cobras, monocled cobras and both Indian king cobra species, preventing death even when the treatment was given 30 minutes after the venom injection. Sunagar said some mice that had become paralysed or showed typical nerve-damage symptoms recovered to a completely normal state after treatment, an effect achieved using relatively small amounts of antibody.

Unlike conventional antivenoms, these recombinant antibodies can be manufactured in microbial or humanised systems without repeatedly immunising horses, and Laustsen said the approach offers a blueprint for building similar antivenoms tailored to snake species in other regions. The treatment has so far only been tested in mice, and the researchers say further studies are needed before it can be evaluated in humans.