Expression, purification and characterization of the recombinant anthrax protective antigen / 生物工程学报

An expression plasmid carrying anthrax protective antigen (PA) gene was constructed, which has an OmpA signal sequence attached to the 5' end of PA gene. The plasmid was transformed into E. coli and induced to express recombinant PA (rPA) . The recombinant protein, about 10% of the total bacterial protein in volume, was secreted to the periplasmic space of the cell. After a purification procedure including ion-exchange, hydrophobic interaction chromatography, and gel filtration, about 15 mg of 95 % pure rPA was obtained from 1-liter culture. The bioactivity of rPA was proved by in vitro cytotoxicity assay. The polyclonal antiserum from rabbits immunized with rPA could inhibit the action of anthrax lethal toxin in vitro, which suggests that antibodies against rPA can provide high passive protection against anthrax. The results reported here may be helpful to develop a safe and efficacious recombinant PA vaccine against anthrax.

Polymorphism of the Bacillus anthracis BclA Protein / 微生物学通报

Bacillus anthracis collagen-like protein(BclA) is a structural component of the exosporium filaments,as well as the immunodominant antigen on the spore surface.The genes encoding BclA proteins were cloned and sequenced from three Bacillus anthracis strains separated from China.It was founded that the BclA proteins of strain A16R and 40048,containing 388 and 322 amino acids,72 and 50 copies of GXX repeat,5 and 3 copies of 21-amino-acid sequence(GPT)_(5)GDTGTT(BclA repeat) respectively,are different from those reported by foreign scholars;while the BclA protein of strain 40022,containing 370 amino acids,66 copies of GXX repeat,and 5 copies of BclA repeat,is identical with that of strain 53169 reported by others.The results are helpful for the molecular typing of B.anthracis strains,and provide a basis for the elucidation of the pathogenesis and immunogenicity of B.anthracis spore.