American scientists extracted snake venom-neutralizing antibodies from the blood of a man who injected himself with snake venom for 18 years and used them to create a three-component serum effective against bites from 13 species of elapids. They plan to further refine the serum to expand its range of action. The study was published in Cell.
Snake venom poisoning kills more than 100,000 people each year. Snake bites are treated with a serum obtained from immunized animals. Each serum is effective against one or more related snake species, but it can sometimes be difficult to determine the specific snake that bit a person and choose the appropriate treatment.
Developing a universal antivenom is also challenging: each snake produces between 5 and 70 protein toxins, so even if a neutralizing agent for each of these toxins were found, combining them all in a single preparation is practically impossible—the combined dose of these agents would exceed the permissible safety parameters. Furthermore, serums obtained through animal immunization often cause side effects in humans.
In an attempt to address these issues, scientists from the US National Institutes of Health, led by Peter D. Kwong, became interested in an unusual case of chronic snake venom exposure: an American man had been injecting himself with venom from various snakes and allowing them to bite him for 18 years. He was exposed to venom 856 times. The scientists analyzed his blood and isolated antibodies against the venom of 19 species of elapid snakes, including various species of cobras, mambas, taipans, and kraits. Each antibody was injected into mice, which were then injected with venom from each of the 19 snakes. This allowed the researchers to determine which antibodies were most effective in neutralizing venom components and then to assemble a cocktail containing a minimal number of components, but in sufficient quantities to neutralize them.
The final serum contained two types of antibodies and varespladib, a toxin inhibitor. The first antibody, LNX-D09, neutralized the venom of six snake species, varespladib provided additional protection against three more, and the second antibody, SNX-B03, extended the cocktail's effectiveness to 13 of the 19 snake species. The cocktail also partially neutralized the venom of the remaining six snake species. The researchers obtained these results after a series of experiments on mice: the animals were first injected with snake venom and then with the three-component serum.
In the future, the scientists will continue their work and hope to create a universal anti-snakebite cocktail or two serums—one for elapid bites and one for viper bites. They also plan to conduct research in collaboration with veterinary clinics in Australia where dogs with snakebites are treated.
British researchers reported an increase in the number of exotic snake attacks on residents of the country. The most serious attacks were by vipers (nine severe poisonings) and elapids (five severe poisonings and one fatality).
