Bioterror agentsA combination ricin/anthrax vaccine shows promise

Princeton, New Jersey-based Soligenix, Inc. last month announced the publication of data demonstrating that the combination of RiVax and VeloThrax induces protective immunity to both ricin toxin and anthrax toxin exposure. RiVax is the company’s candidate vaccine for the prevention of exposure to ricin toxin using an antigen which is completely devoid of the toxic activity of ricin. VeloThrax is the company’s candidate vaccine which employs a derivative of recombinant protective antigen, termed Dominant Negative Inhibitor (DNI), which is a candidate for inclusion in a next generation anthrax vaccine. The results were published online in Vaccine.

The combination treatment of RiVax plus VeloThrax was compared to treatment with either RiVax alone or VeloThrax alone.  The combination treatment was able to provide protection against subsequent challenge with both ricin and anthrax toxin in animal studies. In contrast, mice administered the RiVax vaccine were protected from ricin challenge but not anthrax toxin challenge and mice administered VeloThrax were protected from anthrax toxin challenge but not ricin challenge. These challenges were given at least six months after vaccination and titer levels from the combination were evaluated up to 200 days post vaccination.

Soligenix performed these studies in collaboration with the Wadsworth Center, New York State Department of Health, with Dr. Nicolas J. Mantis, Dr. David Vance, and collaborators under the aegis of a $9.4 million cooperative grant from the National Institute of Allergy and Infectious Diseases (NIAID).

“We are pleased that we have been able to show that a multivalent vaccine for both anthrax and ricin is feasible. The demonstration of simultaneous immunity to ricin and anthrax toxin is a step towards vaccines that can be used in the event of a national emergency,” said Christopher J. Schaber, Ph.D., president and chief executive officer of Soligenix. “We are continuing to develop RiVax using ThermoVax, our proprietary vaccine thermostabilization technology for the stockpiling and distribution of vaccines outside of normal cold chain requirements, under a recent NIAID contract award of up to $24.7 million over five years. Ultimately, we intend to develop the combination vaccine using this same technology.”