Needle-free anthrax vaccine shows promise in animal studies
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PHILADELPHIA, Aug. 25 — Researchers have developed a powdered form of an anthrax vaccine that could potentially be inhaled through the nose and eliminate the need for needle injections. The new vaccine, which appears promising in preliminary animal studies, may offer a faster and easier way to protect the general population as well as soldiers on the battlefield in the event of a deadly bioterror attack, the researchers say.
The development, a joint project of BD Technologies and the U.S. Army Medical Research Institute of Infectious Disease, was described today at the 228th national meeting of the American Chemical Society, the world's largest scientific society.
The vaccine represents a growing pipeline of needle-free drug delivery technologies that are being developed for consumers, such as the FluMistTMintranasal vaccine currently sold to combat influenza. Considered the next generation anthrax vaccine, the new formulation is based on an anthrax recombinant protective antigen (rPA) and can be formulated as a dry powder and self-administered through the nose using a novel, disposable powder delivery device, the researchers say.
The standard delivery for anthrax vaccination is through subcutaneous and intramuscular administration of a liquid formula using conventional needles and syringes, but this method has several drawbacks when employed for mass vaccination, including accidental needle-stick injury, the need for highly trained healthcare professionals and painful injections, the scientists say.
"Our intranasal powder vaccine discovery may provide a highly effective, more flexible, mobile and easy-to-use method of administering the anthrax vaccine in clinical and field settings," says the project's lead investigator, Vince Sullivan, Ph.D., a chemist with BD Technologies' Advanced Drug Delivery group in Research Triangle Park, N.C.
The vaccine has not yet been tested in humans, and additional animal studies are needed, but clinical trials could be possible within the next two to three years, investigators say.
In laboratory tests using rabbits exposed to a lethal dose of inhalation anthrax, nasal immunization with the powder resulted in an 83 to 100 percent survival rate, similar to the protection offered by the injectable formulation, according to a key researcher on the project, Ge Jiang, Ph.D., a pharmaceutical scientist with BD Technologies.
Initial data indicates that the powdered formulation of the rPA antigen, a genetically engineered protein, is also more stable than the liquid version and can withstand wider temperature extremes, allowing it to be stockpiled for longer periods and in more extreme conditions without the need for refrigeration, the researchers say.
Conventional anthrax vaccines, derived from Bacillus anthracis bacteria, require six doses over the course of an 18-month period, with annual booster injections recommended thereafter. It is not yet known how many times and at what dose the new vaccine will need to be administered to maintain protection, the researchers say, adding that this issue is being investigated.
"This is not a cure for anthrax, but may be a better means of protecting at-risk populations from infection," Sullivan explains.
Anthrax vaccine administration is now mandatory for military personnel sent to areas with high risk of exposure and recommended for other groups, including some laboratory and postal workers.
Inhalation anthrax can be fatal if untreated. Doctors currently provide antibiotics once infection has occurred, but treatment must be initiated early to be effective. In addition to improving prevention methods, researchers are continuing to try to develop better drugs to block the deadly bacterium once a person has been exposed.
The American Chemical Society is a nonprofit organization, chartered by the U.S. Congress, with a multidisciplinary membership of more than 159,000 chemists and chemical engineers. It publishes numerous scientific journals and databases, convenes major research conferences and provides educational, science policy and career programs in chemistry. Its main offices are in Washington, D.C., and Columbus, Ohio.
— Mark T. Sampson
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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