Cloning of the Protective Antigen Gene of Bacillus anthracis
ARMY MEDICAL RESEARCH INST OF INFECTIOUS DISEASES FORT DETRICK MD
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The tripartite protein toxin of Bacillus anthracis consists of protective antigen PA, edema factor EF, and lethal factor LF. As a first step in developing a more efficacious anthrax vaccine, recombinant plasmids containing the PA gene have been isolated. A library was constructed in the E. coli vector pBR322 from Bam HI-generated fragments of the anthrax plasmid, pBA1. Two clones producing PA were identified by screening lysates with ELISA enzyme-linked immunosorbent assay. Westem blots revealed a full-size PA protein in the recombinant E. coli, and a cell elongation assay demonstrated biological activity. Both positive clones had a 6 kb insert of DNA, which mapped in the Bam Hi site of the vector. The two inserts are the same except that they lie in opposite orientations with respect to the vector. Thus PA is encoded by the plasmid pBA1.
- Medicine and Medical Research