Mice immunized with DNA encoding a modified Pseudomonas aeruginosa exotoxin A develop protective immunity against exotoxin intoxication

A recombinant plasmid, which contains the Pseudomonas aeruginosa exotoxin A (PE) gene with a C-terminal deletion, was inserted into expression vector pSecTag Xpress. The expression of this bacterial exotoxin in an animal cell was first demonstrated in 3T3 cell by transient transfection and western b lot assay. Recombinant plasmid DNA was then injected intramuscularly to BAL B/c mice, anti-PE specific antibodies were found in all animals vaccinated with plasmid containing the PE gene and with 'detoxicated' recombinant PE p rotein. Mice vaccinated with DNA were protected from the intoxication of le thal dosage of P. aeruginosa exotoxin A. Our results indicated that mice va ccinated with DNA encoding the PE gene could express PE protein in vivo, in duced specific immune response, and provided sufficient protective immunity that safeguarded mice from the injection of lethal dosage of PE toxin. (C) 2000 Elsevier Science Ltd. All rights reserved.