Science takes on bioterrorism.
Anthrax is a likely candidate for bioterrorist attacks since the spores can be easily found in nature or produced in a lab, and the substance can be put into powders, sprays, food, and water. According to the Centers for Disease Control and Prevention (CDC), the microscopic spores are so tiny that they can go undetected by sight, smell, or taste.
In fact, the bacterium that causes anthrax, Bacillus anthracis, is recognized as one of the most significant bioterrorism threats, according to researchers who have developed a new anthrax vaccine. It produces three main components that lead to disease and potential death — lethal toxin, edema toxin, and capsule. The naturally occurring capsule component is what the researchers employed in the new vaccine.
Basically, the bacterium invades the body and grows to high concentrations during an anthrax infection. The capsule’s job is to surround the bacterium and prevent the body’s white blood cells from destroying it, enabling the anthrax infection to progress.
Now, reporting in the journal VACCINE, researchers from the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID) have shown that vaccination with the anthrax capsule completely protected monkeys from lethal inhalation. The vaccine causes the immune system to build antibodies against the capsule, but since it doesn’t contain the whole bacterium, the vaccine cannot do any harm.
In a previous study, the team had shown the partial effectiveness of the anthrax capsule vaccine at two dosages of 2.5 micograms; however, by upping the dosage to 50 micrograms, the scientists achieved complete prevention at a 100 percent rate.
The researchers also tested out a 10 microgram dose in another group of monkeys and achieved an 80 percent protection rate, which they say suggests a dose-ranging effect.
Unfortunately, the monkeys in the non-vaccinated control group “succumbed to the disease,” as the press release states.
The current human vaccines for anthrax primarily contain protective antigen, a protein secreted by the bacteria along with their deadly toxins, but senior author Arthur M. Friedlander explains there are concerns about relying on a single ingredient in a vaccine. It’s possible for anthrax strains to develop resistance against such a vaccine, but add a second component (such as the capsule) and that possibility becomes less likely.
"This new capsule vaccine is expected to work against possible vaccine-resistant strains of anthrax and to protect individuals who may not respond optimally to protective antigen alone,” Friedlander said in the release. “In addition, it could be combined with protective antigen to create a multi-component vaccine that may enhance the efficacy of protective antigen-based vaccines.”
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