August 30, 2013
Study Unlocks New Secret Of Spider Venom – May Lead To More Effective Antivenoms
Brett Smith for redOrbit.com - Your Universe Online
New research from the University of Arizona and Lewis and Clark College in Portland, Oregon has found the venom of the brown recluse and other spiders in the genus Loxosceles produces a much different toxic reaction in the body than previously thought. The finding could eventually lead to more effective anti-venoms, study researchers said.The venom of the brown recluse bite contains a protein that can result in the formation of blackened lesion at the site of a bite or, in rare cases, a lethal systemic reaction in humans. Previous research had indicated this protein attacks lipids that make up the cell membrane by cleaving off the top segment of the molecule – leaving a headless, linear molecule behind.
"We didn't find what we thought we were going to find," said study researcher Matt Cordes, a UA associate professor in the department of chemistry and biochemistry. "We found something more interesting."
According to the team’s report in the journal PLOS ONE, the attacked lipids bent into a ring-like structure and then lost their head segment via the venom instead of remaining linear as previously thought.
"The very first step of this whole process that leads to skin and tissue damage or systemic effects is not what we all thought it was," Cordes said. The UA chemist explained the lipids actually knock off their own heads during the ring-forming process that is initiated by the spider venom.
"Part of the outcome of the reaction, the release of the head group, is the same,” he said. “So initially scientists believed that this was all that was happening, then that became established in the literature."
The cyclical orientation of the headless lipid means that it has chemical properties much different than a linear headless lipid.
"The properties of this cyclic molecule aren't well-known yet, but knowing that it's being produced by toxins in venoms might heighten interest," Cordes said. "Knowing how the protein is actually working and making this cyclic molecule could also lead to better insights on how to inhibit that protein."
When someone is bitten by a brown recluse, doctors can’t predict the type or severity of reaction that will follow, Cordes said, "but what is known is that this protein is the main cause of it. I think if we know how the toxin works, it opens a new door to understanding how the syndrome is initiated as well as the possibility of blocking that process."
Deadly systemic reactions to a brown recluse are fairly rare, occurring only about once every five years in the US. The more common physical reaction is the formation of a dark lesion around the bit site.
"The discovery of this product may be crucial in understanding what exactly is going on in the human reaction," said co-author Greta Binford, an associate professor of biology at Lewis and Clark College.
"People think about the brown recluse with fear," she added. "When I think about a brown recluse or any other spider, I think about how a single spider can have 1,000 chemicals in its venom and there are about 44,000 species, so tens of millions of unique compounds in spider venom that we're in the process of discovering. We have a lot to learn about how these venom toxins work and potential for understanding new chemistry and developing new drugs or treatments."