Pseudomonas aeruginosa outer membrane protein F produced in Escherichia coli retains vaccine efficacy

Abstract

Pseudomonas aeruginosa outer membrane protein F was purified by extraction from polyacrylamide gels of cell envelope proteins of an Escherichia coli strain expressing the cloned gene for protein F. Antisera directed against protein F purified from P. aeruginosa PAO1 reacted with this E. coli strain by immunofluorescence assay and immunoblotting, whereas these antisera were nonreactive with E. coli strains lacking the Pseudomonas protein F gene. The protein F purified from this E. coli strain was used to immunize mice by intramuscular injection of 10 μg of protein F preparation on days 1 and 14, followed by burn and challenge of the mice on day 28. As compared with control mice immunized with E. coli K-12 lipopolysaccharide, immunization with the E. coli-derived protein F afforded significant protection against subsequent challenge with heterologous Fisher-Devlin immunotype 5 and 6 strains of P. aeruginosa. Antisera from mice immunized with the E. coli-derived protein F reacted at bands corresponding to protein F and 2-mercaptoethanol-modified protein F upon immunoblotting against cell envelope proteins of the PAO1, immunotype 5, and immunotype 6 strains of P. aeruginosa and the E. coli strain containing the cloned F gene, but failed to react at these sites in an E. coli strain lacking the F gene. These data demonstrate that P. aeruginosa protein F produced in E. coli through genetic engineering techniques retains its vaccine efficacy in the complete absence of any P. aeruginosa lipopolysaccharide. © 1990 Springer-Verlag New York Inc.