Clinical stage biopharmaceutical company Soligenix announced that its combination vaccine composed of RiVax and VeloThrax successfully induced simultaneous, protective immunity to both ricin and anthrax toxin exposure.
RiVax is an investigational recombinant subunit vaccine developed for the prophylaxis of exposure to ricin toxin. The vaccine uses a unique antigen that is characterized by full lack of the toxic activity of ricin. VeloThrax is a candidate vaccine that uses a derivative of recombinant protective antigen called Dominant Negative Inhibitor (DNI) to prevent exposure to the anthrax toxin.
Used separately as single vaccines, RiVax and VeloThrax induces antibodies that neutralize the toxin from which the vaccines have been derived. Used as a combination vaccine, they induce antibodies that react against both toxins. The neutralizing antibodies were detected until at least 200 days after the vaccines were administered. In addition, protection from the dual vaccine lasted for at least six months after two administrations. Eagle Pharma said this indicates that simultaneous vaccination could be the answer to long-term immunity.
Christopher J. Schaber, President and CEO of Soligenix, said, “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.”
Both ricin and anthrax have been labeled as weapons of biological warfare. In the FBI report Terrorism 2002-2005, the two toxins were noted as the most prevalent agents in weapons of mass destruction (WMD) investigations. In 2001, anthrax-contaminated letters were received in several states where they caused 5 fatalities and 22 infections. In 2004, ricin was detected on an automated mail opener in the Washington office of a U.S. senator. Both incidents remain under investigation by the FBI.
Dr. Schaber said that the vaccines are being developed expressly for military personnel and emergency medical responders who might be exposed to either toxin while on duty. “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.” He said that Soligenix plans to further develop the combined vaccine using its ThermoVax technology.