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Positive Results for Combination Ricin, Anthrax Vaccine

Biodefense Vaccine Development
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Soligenix, Inc. last week announced positive results for the combination of RiVax and VeloThrax to induce 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 a unique antigen that is completely devoid of the toxic activity of ricin. VeloThrax employs a derivative of recombinant protective antigen, termed Dominant Negative Inhibitor (DNI), which is a candidate for inclusion in a next generation anthrax vaccine.

When administered as single a vaccine, each vaccine induced antibodies that were capable of neutralizing the toxin from which the vaccine had been derived.  VeloThrax induced neutralizing antibodies against anthrax toxin and RiVax induced antibodies against ricin toxin.  When combined, the dual vaccine induced antibodies that were reactive against both toxins and these neutralizing antibodies were detected until at least 200 days after the immunization regimens.

Consequently, the combined vaccination provided protection to exposure to both ricin toxin and anthrax toxin that persisted for at least six months after 2 vaccinations, suggesting that long-term immunity upon simultaneous vaccination can be achieved.

Soligenix performed these studies in collaboration with the Wadsworth Institute of the 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). The potency of the vaccine combination was demonstrated in preclinical studies evaluating both production of antibody levels and survival after toxin challenge.

“We are pleased that we have been able to show that the combination of vaccines for these two very important biothreats can be accomplished.  The demonstration of simultaneous immunity to ricin toxin and anthrax is a step towards multivalent vaccines that can be used in the event of a national emergency,” stated Christopher J. Schaber, PhD, President and Chief Executive Officer of Soligenix.

“Both of these vaccines are being developed for military personnel and emergency first responders, and thus it would be extremely useful if the vaccines could be administered simultaneously without compromising the response to either vaccine, while still providing protection against whichever toxin might be encountered,” said Schaber. “Multivalent vaccines will achieve more efficient vaccination with fewer injections; this has the potential to be a distinct advantage in deployment of vaccines if any biothreat agent is actually used as a weapon and will be more useful for vaccination of military personnel and first responders. We intend to develop the combination vaccine using ThermoVax, our proprietary system for stabilizing vaccines for stockpiling and for distribution of vaccines outside of normal cold chain requirements.”

Source: Soligenix, Inc. press release, adapted. RiVax and VeloThrax and ThermoVax are trademarked terms of Soligenix.

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