Immunovaccine Inc., a clinical stage vaccine and immunotherapy company, today announced that three different recombinant protective antigen (rPA) vaccines formulated with its novel DepoVax enhancement technology protected animals against a lethal anthrax challenge after a single vaccination. The National Institutes of Health (NIH) led study demonstrates the potential of DepoVax as a universal enabler of single dose rPA-based anthrax vaccines.


The anthrax challenge study was designed to evaluate the early protection potential of single dose DepoVax/rPA vaccines. A very low dose of rPA that is known to provide partial protection in the rabbit model was used. This allowed a comparison of the potency of the various rPA vaccines formulated in DepoVax.

Rabbits were exposed to a lethal dose of the anthrax causing bacterial spores (B. anthracis) 28 days following a single vaccination. The DepoVax/rPA vaccines provided good protection to animals against anthrax with a single dose, protecting a total of 15 of 24 animals across the three different rPA sources. As expected, control animals injected with a saline solution all succumbed to the anthrax challenge. Animals given a placebo DepoVax vaccine with no antigen also succumbed to anthrax, demonstrating that protection is mediated by the combination of DepoVax and rPA.

“This study shows that DepoVax is compatible with multiple sources of rPA and can enable a single dose rapid response anthrax vaccine. We will be working to establish a path with an rPA provider to advance a DepoVax/rPA vaccine towards Phase I human clinical trials,” said Dr. Marc Mansour, chief executive officer of Immunovaccine.

BioThrax® is the only FDA-licensed anthrax vaccine. However multiple immunizations of BioThrax are needed to provide the necessary protection against exposure to anthrax. Three-doses of intramuscular injections of BioThrax are indicated at 0, 1, and 6 months, followed by booster injections at 12 and 18 months. There is currently no licensed anthrax vaccine that can provide early protection with one dose.

Studies performed to date by the NIH were intended to evaluate Immunovaccine’s DepoVax adjuvanting technology and advance the development of next generation bio-defense vaccines. This latest study was conducted under the National Institute of Allergy and Infectious Diseases (NIAID) of the NIH’s preclinical services program Animal Model of Infectious Diseases contract (HHSN2722012000022I/HHSN27200001).