PREPARATION AND EVALUATION OF PROPERTIES OF PSEUDOMONAS AERUGINOSA EXOTOXIN A CONJUGATE WITH GOLD NANOPARTICLES

Background & Aims: Pseudomonas aeruginosa is an opportunistic pathogen and most important cause of hospital infections, which causes septicemia and death through various virulence factors such as exotoxin A. In the present study, P. aeruginosa exotoxin A (as a toxic factor) was prepared with the aim of obtaining a new recombinant vaccine candidate and conjugated with gold nanoparticles and its immunogenic effects were evaluated in an animal model. Materials & Methods: Native exotoxin A was first extracted and purified from culture medium of P. aeruginosa by selective sedimentation and dialysis. In order to produce recombinant exotoxin A, genomic DNA of this bacterium was cloned in Escherichia coli using a suitable vector. Gold nanoparticles were prepared using Turkevich method and conjugated to the prepared exotoxin A by electrostatic force. Finally, the size and conjugation were confirmed using electron microscopy and fourier-transform infrared (FTIR) spectroscopy, respectively. Finally, quantitative data were presented in average of three repetitions and standard deviation, as well as qualitative data were presented in frequency (percentage). Results: The obtained results showed that P. aeruginosa exotoxin A can be extracted from the culture medium with relative purity. Also, expression of recombinant protein by E. coli and using of E. coli PET22b vector led to production of recombinant exotoxin A in high concentration. The gold nanoparticles were conjugated with both intrinsic and recombinant exotoxin A. The obtained results showed that the gold nanoparticle is well conjugated with exotoxin A. Conclusion: In general, the present study showed that it is possible to produce recombinant and natural exotoxin A with high concentrations in the laboratory and conjugate it with gold nanoparticles.