September 6, 2019

Is it possible to reverse the effects of a life-threatening poison? In the case of one such toxic substance, it very well may be.

A recent study at the Tulane National Primate Research Center (TNPRC) showed for the first time that an experimental drug can save nonhuman primates exposed to deadly ricin toxin. Ricin is derived from the seeds of the castor oil plant, and a single dose of purified ricin powder the size of a few grains of table salt can kill an adult. Due to its toxicity and the availability of its source material, it is considered a leading bioterrorism threat.

It’s also difficult to counter the effects of the lethal toxin once a person has been exposed to it.

“Clinically, there is no treatment that can be administered currently to save someone in the event of an exposure to this toxin,” said study first author Chad Roy, PhD, director of infectious disease aerobiology and biodefense research programs at TNPRC.

In the study, researchers at TNPRC, Mapp Biopharmaceutical Inc., University of Texas Southwestern Medical Center and the New York State Department of Health used a drug comprised of humanized monoclonal antibodies against the toxin. This drug was developed from research of a successful ricin vaccine that was originally tested at TNPRC, and it was engineered to look very similar to the structure of antibodies that were generated from vaccinated nonhuman primates.

“Our study shows proof of concept in a near-clinical animal model, the nonhuman primate, that we finally have a life-saving treatment against one of the world’s most notorious toxin agents,” noted Roy.

Researchers also found the drug was much more effective four hours after exposure as opposed to 12 hours after exposure, indicating a short time window for successful treatment. They plan to develop a stronger version that would “expand the therapeutic window” for effective treatment longer after exposure, Roy said.

Additionally, the scientists hope to develop the drug as a possible preventative therapeutic that emergency workers or members of the military could take before they enter areas contaminated with ricin. The research is part of ongoing federal efforts to develop effective countermeasures against bioterrorism agents.

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