Human antibodies neutralise neurotoxins of 19 of world’s deadliest snakes

New York, May 4 (IANS) By using antibodies from a human donor with a self-induced hyper-immunity to snake venom, scientists have developed the most broadly effective antivenom to date, which is protective against the likes of the black mamba, king cobra, and tiger snakes in mouse trials.

Described in the Cell Press journal Cell, the antivenom combines protective antibodies and a small molecule inhibitor and opens a path toward a universal antiserum.

While exploring, scientists stumbled upon someone hyper-immune to the effects of snake neurotoxins.

“The donor, for a period of nearly 18 years, had undertaken hundreds of bites and self-immunisations with escalating doses from 16 species of very lethal snakes that would normally a kill a horse,” said first author Jacob Glanville, CEO of Centivax, Inc.

After the donor, Tim Friede, agreed to participate in the study, researchers found that by exposing himself to the venom of various snakes over several years, he had generated antibodies that were effective against several snake neurotoxins at once.

“What was exciting about the donor was his once-in-a-lifetime unique immune history,” says Glanville. “Not only did he potentially create these broadly neutralising antibodies, in this case, it could give rise to a broad-spectrum or universal antivenom.”

To build the antivenom, the team first created a testing panel with 19 of the World Health Organization’s category 1 and 2 deadliest snakes across the elapid family, a group which contains roughly half of all venomous species, including coral snakes, mambas, cobras, taipans, and kraits.

Next, researchers isolated target antibodies from the donor’s blood that reacted with neurotoxins found within the snake species tested.

One by one, the antibodies were tested in mice envenomated from each species included in the panel.

In this way, scientists could systematically build a cocktail comprising a minimum but sufficient number of components to render all the venoms ineffective.

To strengthen the antiserum further, the team added the small molecule varespladib, a known toxin inhibitor, which granted protection against an additional three species.

Finally, they added a second antibody isolated from the donor, called SNX-B03, which extended protection across the full panel.

“By the time we reached 3 components, we had a dramatically unparalleled breadth of full protection for 13 of the 19 species and then partial protection for the remaining that we looked at,” said Glanville.

With the antivenom cocktail proving effective in mouse models, the team now looks to test its efficacy out in the field, beginning by providing the antivenom to dogs brought into veterinary clinics for snake bites in Australia.

Further, they wish to develop an antivenom targeting the other major snake family, the vipers.

—IANS

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