Objective       To express recombinant Burkholderia pseudomallei toxin BLF1 and observe its biological characterization.       Methods       The pGEX expression system was adopted to express recombinant BLF1 protein through recombinant DNA technology. The target protein was used to immunize New Zealand white rabbits

and the immunogenicity of the expressed protein was identified by ELISA and Western blotting. The survival rate of BALB/c mice was observed after intraperitoneal injection of different concentrations of rBLF1 protein. The purified p

rotein acted on A549 cells to study its cytotoxicity and the blocking effect of antibody by detecting the number of living cells with CCK-8 kit.       Results      BLF1 gene was amplified by PCR from genomic DNA of Burkholderia pseudomallei and cloned into vector pGEX-6P-2. The recombinant plasmid highly expressing GST-BLF1 protein was identified by restricting enzyme digestion

PCR and DNA sequencing. The expressed protein was about 23×10

3

at molecular weight . After immunization

the titer of polyclonal antibody reached 1∶1 280 000 by ELISA. A specific positive band was found in the target protein position by Western blotting. After intraperitoneal injection of rBLF1 protein

the mortality of BALB/c mice was positively correlated with the dosage of rBLF1 protein. rBLF1 protein can obviously kill A549 cells and antibodies could inhibit its role effectively.       Conclusion      Recombinant rBLF1 protein with biological activity is successfully expressed

and can effectively kill A549 cells. The protein shows cytotoxicity to normal cells

but the normal cells can tolerate the toxin to some extent. All these results provide a basis for further studying pathogenesis of Burkholderia pseudomallei

seeking active prevention and treatment measures

and widening the application of BLF1 toxin in antitumor field.