PRODUCTION AND PURIFICATION OF RECOMBINANT PROTECTIVE ANTIGEN AND PROTECTIVE EFFICACY AGAINST BACILLUS-ANTHRACIS

Recombinant protective antigen (rPA), expressed by Bacillus subtilis W B600 (pPA101), has been purified to homogeneity and the protective eff icacy against a Bacillus anthracis challenge has been investigated. rP A was fractionated from culture supernatant fluid by ammonium sulphate , followed by anion exchange chromatography using DEAE Streamline(TM), anion-exchange chromatography on FPLC MonoQ HR 10/10 and finally, gel filtration chromatography on FPLC Superose 12 HR 10/30, to yield 7 mg rPA per litre of culture. The protective efficacy of rPA against an a irborne challenge with the AMES strain of B. anthracis was determined in the presence of the adjuvants, alhydrogel and Ribi, and compared to that achieved by the current UK human vaccine in guinea pigs. rPA com bined with the Ribi adjuvant was found to provide 100% protection agai nst challenge.