Innovative antivenom may work against the world’s deadliest snakes

A snake antivenom based on antibodies from a hyperimmune man seems to be effective against the bites of multiple species, raising the possibility that a universal treatment may be within reach.

Snake bites cause up to 137,000 deaths a year and around three times as many amputations and disabilities. Antivenoms are currently created for individual snake species using antibodies from sheep or horses that have been exposed to their venom.

But the infusion of non-human antibodies can cause severe side effects, such as life-threatening allergic reactions. It also means that the snake responsible for a bite needs to be identified before an antivenom can be delivered.

Jacob Glanville at biotechnology firm Centivax in San Francisco, California, and his colleagues are looking for broadly neutralising antibodies that could be developed into an antivenom that works against many, or even all, venomous snakes. “Although there are 650 species of venomous snakes, all of their venom uses the same 10 general classes of toxins,” says Glanville.

The researchers first sought out someone who had been bitten multiple times by different snakes. “Perhaps a clumsy snake researcher,” says Glanville. Then he heard media reports about Tim Friede, who, according to his online biography, has “self-administered over 700 escalating doses of snake venom from the world’s deadliest snakes”.

“If anyone could have generated broadly neutralising antibodies against snake venom, it would have been Tim Friede,” says Glanville.

From 40 millilitres of Friede’s blood, the team turned his “immune memory into a library of billions of antibodies”, he says. Promising candidates were then tested on mice that had been exposed to venom from 19 of the World Health Organization’s list of the most dangerous species from the Elapidae family, including several cobra species.

Eventually, two antibodies from Friede’s blood, called LNX-D09 and SNX-B03, along with a toxin inhibitor called varespladib, were made into a treatment. When this was tested on mice, it provided full protection against 13 of the species, including several types of cobra, the tiger snake (Notechis scutatus) and the common taipan (Oxyuranus scutellatus). It also provided partial protection against the remaining six species, including the common death adder (Acanthophis antarcticus).

The next step is to test the treatment on animals that are brought to vet clinics in Australia after a snake bite, and to find antibodies that give coverage against vipers.

Tian Du at the University of Sydney, Australia, says that “finding just two antibodies (with an inhibitor) that can cover such a spectrum of snakes gives hope for a universal treatment in the near-future”.

But Du, who found that the blood-thinning drug heparin could prevent people losing limbs after cobra bites, wants to know if the team’s treatment can prevent necrosis of the skin and muscles.