( Dr. Smallshaw is currently determinin...)Human trial proves ricin vaccine safe, induces neutralizing antibodies; further tests planned

Dr. Smallshaw is currently determining whether the vaccine protects against aerosol and oral administrations in mice. "In a recent series of experiments, we have shown that the vaccine protects mice against lethal doses of ricin administered orally just as well as it protects them against injected ricin," she said. "We are also setting up an aerosol challenge model to determine the protective benefits of the vaccine."

Dr. Vitetta noted that, in humans, exposure by aerosol or food may require inducing immunity in the lung and gut by a very different formulation and vaccination schedule.

Depending on how the ricin is administered as a poison, victims develop fever, nausea and abdominal pain or lung damage before dying within a few days of exposure. There is no antidote after the first few hours of exposure and, because symptoms do not appear until later and often mimic other illnesses, individuals often do not know if they have been exposed until it is too late for treatment, Dr. Vitetta said.

Because castor beans are readily available ?more than 50,000 tons of castor bean extract exist around the world as a byproduct of castor oil production ?public health officials warn that ricin could be used for terrorism. Indeed, there have been several incidents in recent years involving the toxin in the United States and Europe. The CDC classifies ricin as a "Category B" biological agent, which means it is "relatively easy to disseminate."

DOR BioPharma has received an exclusive license for RiVax and is developing large scale manufacturing processes. DOR officials hope to produce a large stockpile for more advanced human clinical testing, product licensing and potential purchases from the U.S. government and other interested parties.

Other UT Southwestern researchers from the Cancer Immunobiology Center involved in the study were Dr. John Schindler, assistant professor and director of clinical trials, and Dr. Elaine Coleman, senior
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Source:UT Southwestern Medical Center