The resulting antivenom contains many nonhuman antibodies irrelevant to venom, some of which can create harmful immune responses. Moreover, it is expensive. A vial of antivenom costs about $2,000, and treatment of one bite can require 25 vials or more. And in the end, the antivenom produced is not always effective in boosting the immune system of a snakebite victim.
Some scientists think genomic technologies could be used to synthesize antivenom, and eventually treat victims more cheaply and effectively. They want to study the venom genes themselves, including their organization, variability and evolution. Doing this requires mapping the snake’s genome.
In Nature Genetics on Monday, one team of researchers released their map of the genome of Naja naja, the Indian cobra. They found 12,346 genes expressed in the venom glands, what they call the “venom-ome” of the animal. Of these, they found 139 toxin genes, the ones that perform the biological reactions specific to toxins. Then they designated 19 of these genes as “venom-ome specific,” expressed only in the venom gland, and that are responsible for a wide range of symptoms in humans, including heart-function problems, paralysis, nausea, blurred vision, internal bleeding and death.
With this catalog of genes specific to venom production, they hope scientists can now begin to use recombinant protein technologies to generate antivenom effective against the venom of the Indian cobra and closely related species. As more snake genomes are completed, scientists may be able to combine species-specific toxins and create broad-spectrum antivenoms that could work against bites from multiple species.
The study’s senior author, Somasekar Seshagiri, a former staff scientist at Genentech and now president of SciGenom Research Foundation, a nonprofit research center in India, said that sequencing a snake’s genome can be done in less than a year for under $100,000.