OprF/I-vaccinated sera inhibit binding of human interferon-gamma to Pseudomonas aeruginosa

The recombinant outer membrane protein OprF/I has been demonstrated in previous studies to protect against Pseudomonas aeruginosa infection through a mechanism of enhanced antibody-mediated opsonophagocytosis. Recent evidence indicates that P. aeruginosa enhances its virulence phenotype as a consequence of binding to human IFN-γ through an outer membrane protein, OprF. In this study, we demonstrate that a single boost injection of OprF/I vaccine elicited a strong OprF/I-specific antibody response in individuals who were previously vaccinated with OprF/I in a clinical trial. The OprF/I-vaccinated sera inhibit P. aeruginosa binding to IFN-γ, suggesting an alternative mechanism by which the OprF/I vaccine confers protection against P. aeruginosa infection.