The research team vaccinated several groups of mice. One month after the second dose, the mice were challenged with lethal doses of spores from a strain of anthrax producing only the capsule. In the group that had received the capsule vaccine, 7 of 12 mice survived challenge. In the control group, which received injections of a placebo instead of the capsule vaccine, none of the 12 mice survived.
Next, the team evaluated the efficacy of capsule vaccines alone or in combination with PA, using the same dosage schedule as before. In this experiment, using a fully virulent strain producing both capsule and toxins, neither capsule nor PA alone protected while the combination vaccine resulted in survival of 9 of 11 mice.
"We demonstrated that protection was even greater when the capsule was combined with PA, compared to when PA was given alone," Friedlander said. "A different formulation could make it even better. The next step will be testing in additional animal models."
Friedlander's colleagues on the study were Donald J. Chabot, Angelo Scorpio, Steven A. Tobery, Stephen F. Little, and Sarah L. Norris.
"This work shows the importance of developing vaccines that target multiple agent-specific targets," said George V. Ludwig, Ph.D., interim science director for USAMRIID. "This helps reduce the possibility of technological surprise when dealing with emerging biological threats."
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Contact: Caree Vander Linden
Caree.Vander-Linden@det.amedd.army.mil
301-619-2285
US Army Medical Research Institute of Infectious Diseases
1-Dec-2004