Clarification: the original article mistakenly contained a reference to "existing vaccines." However, there are no vaccines for bites from venomous animals. As corresponding author Dr. Carlos Chávez-Olórtegu explains: “What exists is therapeutic antivenoms called ‘sera’ that are made in horses. Usually these sera have the capacity of neutralize the toxic effects of the venom. The use of horse sera for the treatment of bite accidents can lead to other problems in people suffer allergic reactions.” [divider] [caption id="attachment_22791" align="alignleft" width="434"] The Loxosceles spider is commonly known as the reaper, recluse and fiddleback spider. Its toxic bite causes skin around the bite to die and can lead to kidney failure and hemorrhaging. (Photo by Kmes Gerholdt/Photolibrary/Getty Images)[/caption]
Researchers have engineered a spider protein that could lead to anti-venom vaccines with the potential to save thousands of lives worldwide, concludes a study published today in Vaccine.
“In Brazil we see thousands of cases of people being bitten by spiders, and the bites can have very serious side-effects,” said Dr. Carlos Chávez-Olórtegui of Federal University Minas Gerais in Brazil, the corresponding author of the study.
“Existing anti-venoms are made of the pure toxins and can be harmful to people who take them,” he said. “We wanted to develop a new way of protecting people from the effects of Reaper spider bites, without them having to suffer from side effects.”
Loxosceles spiders, commonly known as reaper or recluse spiders, are found all over the world and produce harmful venoms. The toxic bite of these spiders causes skin around the bite to die and can lead to more serious effects like kidney failure and hemorrhaging. These Loxosceles spiders are most prevalent in Brazil, where they cause almost 7,000 cases of spider bites every year.
Current antivenoms are problematicAccording to a World Health Organization report, a review of current antivenom production methods indicates that the majority of antivenoms are still produced by traditional technology using animals. The production method involves injecting the venom into animals and removing the resulting antibodies to use in the anti-venom serum for humans. These antibodies enable the human immune system to prepare to neutralize venom from bites. Although this method is somewhat effective, it is problematic as the animals required to produce the antibodies do suffer from the effects of the venom.
Improving conditions – the new methodIn an attempt to improve these conditions, Dr. Chávez-Olortegui and his team of researchers identified a protein that can be engineered in the lab, omitting the need to use real spider venom. It is made up of three proteins rather than the whole venom toxin, so it is not harmful to the immunized animal that produces the antibodies for use in the human serum. It is also more effective than existing approaches and easier to produce than preparing crude venom from spiders.
The researchers tested the lab-engineered protein on rabbits and showed an immune response similar to the way they respond to the whole toxin, previously experienced in the old method. The protein was effective for venom of two sub-species of Loxosceles spiders, which have similar toxins. The rabbits were protected from skin damage at the site of the venom injection and from hemorrhaging.
The authors concluded that this engineered protein may be a promising candidate for vaccination against Loxosceles spider bites in the future. [note color="#f1f9fc" position="alignnone" width=800 margin=10]
The Loxosceles spiderLoxosceles is the genus of spiders that includes the infamous brown recluse spider: Loxosceles reclusa. Most Loxosceles spiders are brown or yellowish and range from 6mm to 12mm in length. They have six eyes in three pairs and each foot has two claws. The spiders are also nocturnal and therefore most likely encountered at night, when they are foraging for food. During the day they hide in secluded places.[/note]
Read the articleThe full article is freely available on ScienceDirect for one month, until June 8, 2013:
“Generation and characterization 1 of a recombinant chimeric protein (rCpLi) consisting of B-cell epitopes of a dermonecrotic protein from Loxosceles intermedia spider venom,” by T. M. Mendes, D. Oliveira, L. Minozzo, R. Machado de Avila, C. Duarte, C. Dias-Lopes, G. Guimarães, L. Felicori, J. C. Minozzo, C. Chávez-Olortegui [DOI: http://dx.doi.org/10.1016/j.vaccine.2013.03.048] Vaccine, published by Elsevier.