Development of an in vitro-based potency assay for anthrax vaccine.

The potency assay currently used to evaluate consistency of manufacture for the anthrax vaccine is contingent upon meeting specified parameters after statistical analysis of the percent survival and time to death of vaccinated guinea pigs after challenge with spores of a virulent strain of Bacillus anthracis. During the development of a new anthrax vaccine based upon recombinant protective antigen (rPA) adsorbed to aluminum hydroxide gel (Alhydrogel), we found that the serological response of female A/J mice, as measured by a quantitative anti-rPA IgG ELISA, may be an effective method to monitor a manufacturer's consistency for rPA-based vaccines. An advantage of the proposed in vitro-based potency assay is that it will not need stringent biosafety containment measures as required by the current guinea pig potency assay.