While only about 10 percent of the roughly 4,000 known snake species have venom that can harm a human, using genetics to determine which snakes could be deadly could speed up developing better treatments for bites. A new tool called VenomCap can help scientists hone in on venom at a genetic level, so we can know which ones are likely carrying deadly toxins. The method is detailed in a study published September 19 in the journal Molecular Ecology Resources.
“We’ve developed a tool that can tell us which venom-producing genes are present across an entire snake family in one fell swoop,” Sara Ruane, a study co-author and the Assistant Curator of Herpetology at the Field Museum in Chicago, said in a statement.
Know your venoms
Every living thing is made up of DNA, which contains the genome–or, instructions for all of the functions in an organism’s body. The snake genome has roughly 18,00 to 23,000 genes depending on the species. Thousands of these genes are involved in producing venom and different snake species use multiple combinations and versions of genes to produce toxins.
[Related: Snake venom’s deadly secrets decoded with fake blood vessels.]
“It’s important to know what’s in a snake’s venom, because different kinds of venom do different things–some venoms affect the nervous system, some affect the circulatory system, some affect cell function,” said Ruane. “Knowing what’s in a certain kind of venom can help in the development of antivenom for treating that kind of snakebite.”
Additionally, some of the compounds in snake venoms have been used to make medicines humans use. The first ACE-inhibitor drug for treating high blood pressure was created using a compound in Brazilian pit viper venom.
“You can harness the power of death in a controlled way,” says Ruane.
How VenomCap works
There are thousands of genes that are known to produce venom and each snake’s whole genome has tens of thousands of genes. This makes it difficult to pinpoint the ones that are present for venom. To help this process along, Ruane and the team on this study developed VenomCapto help find venom genes.
VenomCap is a set of probes that captures groups of molecules called exons that are designed to interact with a specific group of genes. VenomCap can bind with any of the several thousands of genes that are known to be involved with venom production in snakes. Instead of sequencing a snake’s entire genome–which costs a lot of time and money–and searching through over 2,000 possible venom-producing genes, VenomCap may be a quicker, easier alternative to scientists to see if a snake has these genes and which ones.
In the new study, the team tested VenomCap’s ability to bind with venom-producing genes. They used tissue samples from 24 kinds of snakes from the family Elapidae. This family of about 400 species includes coral snakes, cobras, and mambas and is considered medically important since their bites can destroy tissue, cause the heart to collapse, induce blindness, and more.
[Related: Why are there so many snakes?]
Earlier genomic studies have shown that many of the venom-producing genes Elapidae have. According to the study, VenomCap matched those results with 76 percent accuracy, on average. The team believes that VenomCap can be used with tissues that have been previously collected from anywhere in a snake’s body, instead of just those coming directly from the venom glands.
VenomCap could also make it easier for scientists to examine the relationship between snakes in the elapid family, their lifestyles, and the types of venoms that they produce.
“Let’s say you’re interested in some closely-related species of snakes that look different from each other, live in different environments, and eat different things,” said Ruane. “VenomCap could help scientists compare the venoms that these snakes produce, and that could help answer bigger-picture questions of whether venoms evolve to match the snakes’ lifestyles, or if their lifestyles evolve to match the venom they produce.”
A global health threat
Using a tool like VenomCap could help scientists develop better methods for treating deadly snake bites. According to the World Health Organization, roughly 5.4 million people are bitten by snakes each year. Their bites lead to 1.8 to 2.7 million cases of envenomation and 81,410 to 137,880 deaths annually.
“Snake bite is considered a neglected disease on the global-scale,” said Ruane. “In the United States, we don’t come into contact with venomous snakes that often, and when we do, we have extremely good medical treatment–if you expeditiously go to the hospital with a snakebite, you are almost certainly not going to die.”
However, in other parts of the world, venomous snakes are much more common. Australia has the most known venomous snake species of any country, with India, several northern African countries not far behind. Bites may occur in places that are remote and far away from medical attention. Hospitals might not have the right kinds of antivenom on hand due to short supplies.
“Any kind of work that looks at snake venom and helps us identify the venoms present in different species can be extremely important to provide baseline data for developing effective treatments,” said Ruane.
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