43rd ICAAC
A meeting of the American Society for Microbiology

September 14-17, 2003, Chicago, IL

 For more information on any presentation at the 43rd ICAAC contact Jim Sliwa, ASM Office of Communications at jsliwa@asmusa.org



EMBARGOED UNTIL:  Tuesday, September 16, 1:30 p.m.

(Session 162, Paper G-1666)

Thomas Evans
Vical Incorporated
San Diego, CA 
Phone: 858-646-1158

An investigational DNA plasmid-based anthrax vaccine developed by Vical, Inc. was shown in rabbits to induce a potent immune response and provide long-term protection against a lethal challenge of aerosolized anthrax spores. Results of this study indicate that DNA vaccines provide protection for more than seven months.

DNA vaccines are ideal for biodefense applications because they can be constructed more quickly than conventional vaccines. The potentially rapid and consequently flexible development of these vaccines may be especially critical in the fight against bioterror agents, which could potentially be modified through genetic engineering to circumvent protection provided by conventional vaccines. Vical’s DNA vaccine, based on the company’s patented vaccine delivery technologies, is designed to enable recipients to mount an immune response against both lethal factor and protective antigen, two proteins secreted from the anthrax bacteria that combine to form lethal toxin that causes severe illness or death. This multi-valent approach provides a second line of defense; anthrax genetically engineered to evade one level of protection by the immune system may still be caught by the other. Conventional vaccines target only one of the two components of anthrax lethal toxin.

Animals in the study received the vaccine three times (at 0, 28 and 56 days). More than seven months after their last vaccination, all of these animals were still completely protected from a challenge with a lethal dose of inhaled anthrax.. At the time of the challenge, the animals also continued to display elevated levels of antibodies.

The study was conducted by researchers at Vical, with assistance from The Ohio State University and The Naval Medical Research Center. Funding for the study was provided by the U.S. National Institute of Allergy and Infectious Disease (NIAID) through a Small Business Technology Transfer Research grant. Continued development of the program is being funded by a three-year, $5.7 million SBIR grant. The study will be presented at ICAAC 2003 in Chicago Illinois on September 16th. The presentation is entitled: Long-term protection of rabbits from B. anthracis aerosolized spore challenge using a formulated DNA vaccine.

For additional information about this study, the anthrax vaccine, Vical’s patented gene delivery technology, or Vical, please contact Janeen Hicks at 858.860.0266 x120.