Genetic and Physiological Control of Protective Antigen Synthesis by Bacillus anthracis

摘要

The primary objective of the research is to gain information and to develop genetic systems that will contribute to the development of an improved vaccine for anthrax. During the six months covered by this progress report attention was focused on 1) the capsule plasmid, pX02, of Bacillus anthracis, 2) extending the B. anthracis mating system to include Bacillus subtilis as a participant, and 3) characterization of additional Bacillus thuringiensis conjugative plasmids that are effective in B. anthracis. Proof that pX02 is involved in capsule synthesis came from experiments in which the plasmid was transferred by CP-51-mediated transduction and by a mating system in which plasmid transfer is mediated by a B. thuringiensis fertality plasmid, pX012. Results of experiments discussed in this report suggest very strongly that in two examples which were investigated the mutation occurred on the plasmid. When the mutant pX02 was replaced by wild-type pX02, the variants acquired the capsule-positive phenotype. Preliminary results indicate that the fertility plasmid pX012, which can transfer itself as well as other plasmids within and among strains of B. anthracis, B. cereus, and B. thuringiensis, can also function in B. subtilis. In addition to the B. thuringiensis fertility plasmids, pX011 and pX012, which are active in B. anthracis, four new B. thuringiensis fertility plasmids have been found and they are all active in B. anthracis.